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{{Short description|Active stratovolcano in Luzon, Philippines}} | |||
{{featured article}} | |||
{{Redirect|Pinatubo|the horse|Pinatubo (horse)}} | |||
<!-- BEGIN WikiProject Mountains infobox --> | |||
{{pp-move|small=yes}} | |||
{{Infobox Mountain | |||
{{Use mdy dates|date=November 2024}} | |||
| Name = Mount Pinatubo | |||
{{Use Philippine English|date=August 2020}} | |||
| Photo = Pinatubo ash plume 910612.jpg | |||
{{Infobox mountain | |||
| Caption = Ash plume of Pinatubo during 1991 eruption | |||
| name = Mount Pinatubo | |||
| Elevation = 1,486 metres (4,875 feet) | |||
| photo = File:Mt Pinatubo trekking - panoramio (5).jpg | |||
| Location = ], ], ]<br/>], ], ]<br/>], ], ] | |||
| photo_caption = Mount Pinatubo crater lake in 2012 | |||
| Range = ] | |||
| map = Philippines | |||
| Prominence = | |||
| map_alt = | |||
| Coordinates = {{coord|15|7.8|N|120|21.0|E|type:mountain|display=inline,title}} | |||
| map_caption = Location within the Philippines | |||
| Topographic map = | |||
| location = ] | |||
| map_relief = | |||
| Age =1.1 million years | |||
| label_position = left | |||
| Last eruption = 1991<ref name="smithsonian">{{VNUM|1=0703-083}}</ref> | |||
| elevation = {{plainlist| | |||
| First ascent = | |||
*{{cvt|1486|m|ft}} (current) | |||
| Easiest route = | |||
*{{cvt|1745|m|ft}} (before 1991 eruption)}} | |||
| Translation = | |||
| prominence_m = | |||
| Language = english | |||
| prominence_ref = | |||
| listing = ] | |||
| language = Tagalog | |||
| pronunciation = {{IPAc-en|ˌ|p|iː|n|ə|ˈ|t|uː|b|oʊ}} | |||
| range = ] | |||
| coordinates = {{coord|15|08|30|N|120|21|00|E|type:mountain_region:PH_scale:100000|format=dms|display=inline,title}} | |||
| topo = | |||
| coordinates_ref = | |||
| type = ]<ref name="SI">{{cite web|url=http://volcano.si.edu/volcano.cfm?vn=273083|title=Pinatubo|department=]|publisher=]|access-date=January 23, 2020|archive-date=January 23, 2020|archive-url=https://web.archive.org/web/20200123030236/http://volcano.si.edu/volcano.cfm?vn=273083|url-status=live}}</ref> | |||
| volcanic_arc = ] | |||
| age = Between 635,000 ± 80,000<br />and 1.1 ± 0.09 million years<ref>{{cite web|url=http://volcano.phivolcs.dost.gov.ph/update_VMEPD/Volcano/VolcanoList/pinatubo.htm|title=Pinatubo Volcano|publisher=The ] (PHIVOLCS)|access-date=August 12, 2008|archive-url=https://web.archive.org/web/20090129222823/http://volcano.phivolcs.dost.gov.ph/update_VMEPD/Volcano/VolcanoList/pinatubo.htm|archive-date=January 29, 2009|url-status=dead}}</ref> | |||
| last_eruption = November 30, 2021<ref>{{cite gvp|title=Pinatubo: Eruptive History|vn=273083|vtab=Eruptions|access-date=August 31, 2021}}</ref> | |||
| first_ascent = | |||
| easiest_route = | |||
| map_size = | |||
| range_coordinates = | |||
| country = ] | |||
| state = ] | |||
| state_type = Region | |||
| region = {{hlist | ] | ] | ] }} | |||
| region_type = Provinces | |||
| mapframe = yes | |||
| mapframe-wikidata = yes | |||
}} | }} | ||
{{History of the Philippines}} | |||
<!-- END WikiProject Mountains infobox --> | |||
'''Mount Pinatubo'''<ref>{{langx|xsb|Bakil nin Pinatobo}}; {{langx|pam|Bunduk/Bulkan ning Pinatubu, Bunduk ning Apu Malyari}}; {{langx|pag|Palandey/Bulkan na Pinatubu}}; {{langx|ilo|Bantay Pinatubo}}; {{langx|tl|Bundok/Bulkang Pinatubo}} {{IPA|tl|pɪ.nɐˈtuː.boʔ|IPA}}</ref> is an active ] in the ] in ] in the ]. Located on the ] of ], ] and ] provinces,<ref name="Topo">{{cite web|url=http://www.lib.utexas.edu/maps/ams/philippines/txu-oclc-6539351-nd51-1-450.jpg|title=Tarlac map|publisher=University of Texas in Austin Library|access-date=August 2, 2011|archive-date=July 31, 2019|archive-url=https://web.archive.org/web/20190731132546/https://legacy.lib.utexas.edu/maps/ams/philippines/txu-oclc-6539351-nd51-1-450.jpg|url-status=live}}</ref><ref> {{Webarchive|url=https://web.archive.org/web/20161130023904/https://books.google.com/books?id=Hv9GAQAAIAAJ |date=November 30, 2016 }}, pg. 141. Government Printing Office, Washington, 1901.</ref> most people were unaware of its eruptive history before the pre-eruption volcanic activity in early 1991. Dense ]s, which supported a population of several thousand indigenous ], heavily ] and obscured Pinatubo. | |||
'''Mount Pinatubo''' is an active ] located on the island of ] in the ], at the intersection of the borders of the provinces of ], ], and ]. Ancestral Pinatubo was a stratovolcano made of ] and ]. Before 1991, the mountain was inconspicuous and heavily ]. It was covered in dense ] which supported a population of several thousand indigenous people, the ], who had fled to the mountains from the lowlands when the ] conquered the Philippines in 1565. | |||
Pinatubo is known for its ]-6 ], the second-largest terrestrial eruption of the 20th century after the 1912 eruption of ] in ].<ref name=Pinatubo1991>{{cite web|title=The Cataclysmic 1991 Eruption of Mount Pinatubo, Philippines|url=http://pubs.usgs.gov/fs/1997/fs113-97/|access-date=April 9, 2007|archive-date=August 25, 2013|archive-url=https://web.archive.org/web/20130825233934/http://pubs.usgs.gov/fs/1997/fs113-97/|url-status=live}} {{PD-notice}}</ref> The eruption coincided with ] making landfall in the Philippines, which brought a dangerous mix of ash and rain to nearby towns and cities. Early predictions led to the evacuation of tens of thousands of people, saving many lives. The eruption severely damaged surrounding areas with ]s, ]s, and later, flooding ]s caused by rainwater re-mobilizing volcanic deposits. This destruction affected infrastructure and altered river systems for years. <ref name=Pinatubo1991/><ref>{{cite web|author1=Rodolfo|author2=Umbal|author3=Alonso|url=http://pubs.usgs.gov/pinatubo/rodolfo/index.html|title=Two Years of Lahars on the Western Flank of Mount Pinatubo: Initiation, Flow Processes, Deposits, and Attendant Geomorphic and Hydraulic Changes|publisher=USGS Publications|access-date=March 7, 2012|archive-date=March 16, 2012|archive-url=https://web.archive.org/web/20120316034034/http://pubs.usgs.gov/pinatubo/rodolfo/index.html|url-status=live}}</ref> Minor ]-forming eruptions inside the caldera continued from 1992 to 1993. | |||
The volcano's eruption in June 1991 produced the second largest terrestrial eruption of the 20th century.<ref name=Pinatubo1991>{{Citation | title=The Cataclysmic 1991 Eruption of Mount Pinatubo, Philippines | url=http://pubs.usgs.gov/fs/1997/fs113-97/ | access-date=2007-04-09}}</ref> The 1991 eruption had a ] (VEI) of 6, and came some 450-500 years after the volcano's last known eruptive activity (estimated as VEI 5, the level of the ]), and some 500-1000 years after previous VEI 6 eruptive activity.<ref>{{Citation | |||
|url=http://www.volcano.si.edu/world/volcano.cfm?vnum=0703-083&volpage=erupt | |||
|title=Global Vulcanism Program: Pinatubo — Eruptive History | |||
|publisher=Smithsonian Institution | |||
|accessdate=2008-01-22}}</ref> Successful predictions of the onset of the climactic eruption led to the evacuation of tens of thousands of people from the surrounding areas, saving many lives, but as the surrounding areas were severely damaged by ]s, ash deposits, and later, ]s caused by rainwater remobilizing earlier volcanic deposits, thousands of houses were destroyed.<ref name=Pinatubo1991 /> | |||
The |
The 1991 eruption had worldwide effects. It released roughly {{convert|10|e9t|ST|lk=on}} or {{convert|10|km3|cumi|abbr=on}} of magma, bringing large amounts of minerals and toxic metals to the surface. It also released {{convert|20|e6t|e6ST|abbr=off}} of {{chem|S|O|2|link=Sulfur_dioxide}}. It ejected more ] into the ] than any eruption since ] in 1883. In the following months, aerosols formed a global layer of ] haze. Global temperatures dropped by about {{convert|0.5|C-change|F-change|1}} in the years 1991–1993,<ref>{{cite web|url=http://pubs.usgs.gov/pinatubo/self/|title=The Atmospheric Impact of the 1991 Mount Pinatubo Eruption|author1=Stephen Self|author2=Jing-Xia Zhao|author3=Rick E. Holasek|author4=Ronnie C. Torres|author5=Joey McTaggart|name-list-style=amp|year=1999|access-date=July 25, 2014|archive-date=August 2, 2014|archive-url=https://web.archive.org/web/20140802181316/http://pubs.usgs.gov/pinatubo/self/|url-status=live}}</ref> and ] temporarily increased significantly.<ref name="Science News">{{cite magazine|url=http://www.thefreelibrary.com/Mt.+Pinatubo's+cloud+shades+global+climate.-a012467057|title=Mt. Pinatubo's cloud shades global climate|magazine=Science News|access-date=March 7, 2010|archive-date=January 7, 2012|archive-url=https://web.archive.org/web/20120107063251/http://www.thefreelibrary.com/Mt.+Pinatubo%27s+cloud+shades+global+climate.-a012467057|url-status=live}}</ref> | ||
==Geography== | |||
==Overview of the Mount Pinatubo area== | |||
] | |||
The volcano is about {{convert|87|km|mi|sp=us}} northwest of ], the capital of the Philippines. Near Mount Pinatubo are former military bases that were maintained by the United States. The ] was {{convert|37|km|mi|sp=us}} south of Pinatubo, and the extent of ] was just {{convert|14|km|mi|sp=us}} east of the volcano's summit.<ref name=K-118B>Tactical Pilotage Chart, Sheet K-11B, ], Department of Defense, 1982.</ref> The volcano is near to about 6 million people.<ref> {{webarchive|url=https://web.archive.org/web/20130928012059/http://www.census.gov.ph/sites/default/files/attachments/hsd/pressrelease/Population%20and%20Annual%20Growth%20Rates%20for%20The%20Philippines%20and%20Its%20Regions%2C%20Provinces%2C%20and%20Highly%20Urbanized%20Cities%20Based%20on%201990%2C%202000%2C%20and%202010%20Censuses.pdf |date=September 28, 2013 }}</ref> | |||
] | |||
Pinatubo is part of a chain of volcanoes which lie along the western edge of the island of ]. They are ] ]es, formed by the ] sliding under the ] along the ] to the west. The word 'pinatubo' means 'to have made grow' in ] and ] {]}, which may suggest a knowledge of its previous eruption in about AD 1500, although there is no oral tradition among local people of earlier large eruptions. ''Pinatubo'' might instead mean a fertile place where crops can be made to grow. | |||
==History== | |||
Before the catastrophic eruption of 1991, Pinatubo was an inconspicuous volcano, unknown to most people in the surrounding areas. Its summit was 1,745 m (5,725 ft) above sea level, but only about 600 m above nearby ]s, and about 200 m higher than surrounding peaks, which largely obscured it from view. An indigenous people, the ] (also spelt Ayta), had lived on the slopes of the volcano and in surrounding areas for several centuries, having fled the lowlands to escape persecution by the ]. They were a ] people who were extremely successful in surviving in the dense jungles of the area. These people also grew some staple crops such as wheat, barley and rice. | |||
Even before the 1991 eruption, Mount Pinatubo had little ]: it was {{convert|1745|m|ft|abbr=on}} above sea level, only about {{convert|600|m|ft|abbr=on}} above nearby ]s, and only about {{convert|200|m|ft|abbr=on}} higher than surrounding peaks, which largely obscured it from view.<ref> {{webarchive|url=https://web.archive.org/web/20081204005825/http://library.thinkquest.org/C0112681/Eng/Normal/Volcanoes_World/southeast_asia/philippines/pinatubo.html |date=December 4, 2008 }}</ref> It is part of a chain of ] which lie along the western side of the island of ] called the ].<ref>{{Cite web|url=http://www.pinoymountaineer.com/2008/05/central-luzon.html|title=Hiking guide: Central Luzon mountains|date=May 19, 2008|website=Pinoy Mountaineer|access-date=August 21, 2020|archive-date=August 4, 2020|archive-url=https://web.archive.org/web/20200804041713/http://www.pinoymountaineer.com/2008/05/central-luzon.html|url-status=live}}</ref> | |||
Pinatubo belongs to the ] of the ], which consists of ], ], Mount Mataba and Mount Pinatubo.<ref>U.S. War Department. {{Webarchive|url=https://web.archive.org/web/20140606151453/http://books.google.com/books?id=Hv9GAQAAIAAJ&pg=141 |date=June 6, 2014 }}</ref> They are ] volcanoes, formed by the ] sliding under the ] along the ] to the west. Mount Pinatubo and the other volcanoes on this ] arise due to ]tic occlusion from this ] ] boundary.<ref>{{cite web|url=http://vulcan.wr.usgs.gov/Volcanoes/Philippines/Pinatubo/description_pinatubo.html|title=Description: Mount Pinatubo, Philippines|date=July 13, 2009|author=Topinka, Lyn|access-date=April 18, 2010|publisher=United States Geological Survey|archive-date=June 3, 2010|archive-url=https://web.archive.org/web/20100603020948/http://vulcan.wr.usgs.gov/Volcanoes/Philippines/Pinatubo/description_pinatubo.html|url-status=live}}</ref> | |||
In total, about 30,000 people lived on the flanks of the volcano in ]s (villages) and other small settlements. The dense jungle covering most of the mountain and surrounding peaks supported the hunter-gathering Aeta, while on the surrounding flatter areas, the abundant rainfall (almost 4 m annually) provided by the ] climate and the fertile volcanic soils provided excellent conditions for ], and many people grew ] and other staple foods. About 500,000 people continue to live within 40 km of the mountain, with population centres including the 150,000 in ], and 20,000 at ]. | |||
Pinatubo is flanked on the west by the ] ] Complex, which is an easterly-dipping section of ] oceanic crust uplifted during the late ]. The Tarlac Formation north, east and southeast of Pinatubo consists of marine, nonmarine and volcanoclastic sediments formed in the late ] and ].<ref name="Newhall"/> | |||
Several important river systems have their sources on Pinatubo, with the major rivers being the Bucao, Santo Tomas, Maloma, Tanguay and Kileng rivers. Before the eruption, these river systems were important ]s, but the eruption filled many valleys with deep pyroclastic deposits. Since 1991, the rivers have been clogged with ], and the valleys have seen frequent ]s. Studies show that the river systems will take many years yet to recover from the 1991 eruption. | |||
The most recent study of Mount Pinatubo before the activities of 1991 was the overall geological study in 1983 and 1984 made by F. G. Delfin for the ] as part of the surface investigations of the area before exploratory drilling and well testing for ] sources in 1988 to 1990. He recognized two life histories of the mountain, which he classified as "ancestral" and "modern" Pinatubo.<ref name="Newhall"/><ref>{{cite web|author1=Delfin, F.G.|author2=Villarosa, H.G.|author3=Layugan, D.B.|url=http://pubs.usgs.gov/pinatubo/delfin/index.html|title=Geothermal Exploration of the pre-1001 Mount Pinatubo Hydrothermal System|publisher=United States Geological Survey Publications|access-date=March 7, 2012|archive-date=March 16, 2012|archive-url=https://web.archive.org/web/20120316033736/http://pubs.usgs.gov/pinatubo/delfin/index.html|url-status=live}}</ref> | |||
==Geological history== | |||
Although there seems to be no local knowledge of the previous large eruptions in the Pinatubo area, several Aeta residents reported in 1991 that their elders recalled small explosions in the past. Pinatubo was a known ] area before the 1991 eruption, and small steam explosions are quite common in such areas. It was only after volcanic activity began in 1991 that geologists studied the eruptive history of the region in any detail. Eruptions at the site can be divided into two major eras. | |||
===Ancestral Pinatubo=== | ===Ancestral Pinatubo=== | ||
] | ] | ||
] | |||
Much of the rugged land |
Activity of Ancestral Pinatubo seems to have begun about 1.1 million years ago and probably ended tens of thousands of years or more before the birth of "modern" Pinatubo. Much of the rugged land around the present volcano consists of remnants of "ancestral" Pinatubo. It was an ] and ] ] whose eruptive activity was much less explosive than modern Pinatubo. Its center was roughly where the current volcano is. The projected height of the mountain is up to {{convert|2300|m|abbr=on}}, or 1.43 miles above ] if it were a lone peak, based on a profile fitting to the remaining lower slopes, or lower if it had more than one peak.<ref name="Newhall"/> | ||
The old volcano is exposed in the walls of an old {{convert|3.5|x|4.5|km|abbr=on}} wide ], referred to as ''Tayawan Caldera'' by Delfin. Some of the nearby peaks are the remnants of ancestral Pinatubo, left behind when the softer parts of the old mountain slopes were eroded by ]. Ancestral Pinatubo is a ] with modern Pinatubo as the new cone. | |||
Mount Dorst, to the east, is part of the dip slope of the ancestral Pinatubo. Several mountains near modern Pinatubo are old satellite vents of ancestral Pinatubo, forming ]s and lava domes. These satellite vents were probably active around the same time as the ancestral volcano and include the domes of Mount Negron, Mount Cuadrado, Mount Mataba and the Bituin and Tapungho plugs.<ref name="Newhall"/> | |||
The eruptive activity of ancestral Pinatubo was much less explosive than modern Pinatubo, and probably ended about 45,000 years ago. After a long period of dormancy, modern Pinatubo was born in eruptions beginning about 35,000 years ago. | |||
===Modern Pinatubo=== | ===Modern Pinatubo=== | ||
* c. 79,000 BC:<ref>{{Cite journal|last=Ku|first=Yueh-Ping|last2=Chen|first2=Chang-Hwa|last3=Newhall|first3=Christopher G.|last4=Song|first4=Sheng-Rong|last5=Yang|first5=Tsanyao Frank|last6=Iizuka|first6=Yoshiyuki|last7=McGeehin|first7=John|date=February 1, 2008|title=Determining an age for the Inararo Tuff eruption of Mt. Pinatubo, based on correlation with a distal ash layer in core MD97-2142, South China Sea|url=http://ntur.lib.ntu.edu.tw/bitstream/246246/172549/1/18.pdf|journal=Quaternary International|series=Global Tephra Studies: John Westgate and Andrei Sarna-Wojcicki Commemorative Volume|language=en|volume=178|issue=1|pages=138–145|doi=10.1016/j.quaint.2007.02.025|issn=1040-6182}}</ref> After a long period of ], Modern Pinatubo was born in Ancestral Pinatubo's cataclysmic and most explosive eruptions, estimated to be five times larger than the June 1991 eruption. It deposited all around the volcano up to {{convert|25|km3|cumi|abbr=on}} of ] material up to {{convert|100|m|sp=us}} thick. The total volume of volcanic material ejected during the eruptions is unknown. The removal of so much material from the underlying ] resulted in the Tayawan ]. The violent eruptive period started by the eruption is referred to by Delfin as the ''Inararo Eruptive Period'', named after a village that was destroyed in the 1991 eruption.<ref name="Newhall"/> | |||
The birth of modern Pinatubo occurred in the most explosive eruption in its history, which deposited ] material up to 100 meters thick on all sides of the mountain. The total volume of material erupted may have been up to ]s (6 mile³), and the removal of this amount of material from the underlying ] led to the formation of a large ]. | |||
Later eruptions of modern Pinatubo occurred episodically and lasted for periods much shorter than the repose intervals between them. Subsequent eruptions and eruptive period occurred about: | |||
Later large eruptions occurred 17,000, 9000, 6000–5000 and 3900–2300 years ago. Each of these eruptions seems to have been very large, ejecting more than 10 km³ of material and covering large parts of the surrounding areas with pyroclastic flow deposits. Scientists estimate that the most recent eruption before 1991 happened about 500 years ago, and after that, the volcano lay dormant. Its slopes became completely covered in dense ], and eroded into gullies and ravines. | |||
*c. 15,000 BC (Sacobia Eruptive Period) | |||
*c. 7000 BC (Pasbul Eruptive Period). Its eruptions were as energetic, if not as voluminous as the Inararo eruptions. | |||
*c. 4000–3000 BC (Crow Valley Eruptive Period). This and the Mara-unot period's eruptions were smaller than the Inararo eruptions but about two to three times as big as that of 1991 based on the pyroclastic flow runout distances and depths of valley filling. | |||
*c. 1900–300 BC (Maraunot Eruptive Period) | |||
*c. AD 1500 (Buag Eruptive Period). Its eruptions were roughly the same size as those of 1991. | |||
Each of these eruptions seems to have been very large, ejecting more than {{cvt|10|km3||}} of material and covering large parts of the surrounding areas with pyroclastic flow deposits. Some eruptive periods have lasted decades and perhaps as much as several centuries and might appear to include multiple large explosive eruptions.<ref name="Newhall"/> | |||
==1991 awakening== | |||
] | |||
The maximum size of eruptions in each eruptive period though has been getting smaller through the more than 35,000-year history of modern Pinatubo, but this might be an artifact of erosion and burial of older deposits. The oldest eruption of modern Pinatubo, Inararo, was also its largest. | |||
On ] ], an ] of ] 7.8 (comparable in size to the ] and the ]) struck central Luzon. Its epicenter was at ], about 100 km northeast of Pinatubo, leading some volcanologists to speculate that it might ultimately have triggered the 1991 eruption, although this is impossible to prove conclusively. Two weeks after the earthquake, local residents reported ] coming from the volcano, but scientists visiting the mountain found that small ]s rather than any eruptive activity were responsible. | |||
The 1991 eruption was among the smallest documented in its geologic record.<ref name="Newhall"/> | |||
On ] ], a succession of earthquakes was felt by villagers on the north-western side of the volcano. Further earthquakes of increasing intensity were felt over the next two weeks, and it became clear some kind of volcanic activity was imminent. On ], the volcano awoke, with ]s occurring near the summit along a 1.5 km long ]. Over the next few weeks, small eruptions continued, dusting the surrounding areas with ]. ]s recorded hundreds of small earthquakes every day. | |||
The volcano has never grown very large between eruptions, because it produces mostly unwelded, easily erodible deposits and periodically destroys the viscous domes that fill its vents. After the Buag eruption (c. 1500 AD), the volcano lay dormant, its slopes becoming completely covered in dense ] and eroded into gullies and ravines. The c. 500-year repose though between the Buag and present eruptive periods is among the shorter repose periods recognized in its geologic history.<ref name="Newhall">{{cite book|editor-first1=Christopher G.|editor-last1=Newhall|editor-last2=Punongbayan|editor-first2=Raymundo S.|chapter=Eruptive history of Mount Pinatubo|chapter-url=http://pubs.usgs.gov/pinatubo/newhall/index.html|title=FIRE and MUD: Eruptions and Lahars of Mount Pinatubo, Philippines|url=http://vulcan.wr.usgs.gov/Volcanoes/Philippines/Pinatubo/Publications/FireMud/about_the_book.html|publisher=Philippine Institute of Volcanology and Seismology; University of Washington Press|year=1996|isbn=978-0-295-97585-6|access-date=October 5, 2008|archive-date=January 10, 2009|archive-url=https://web.archive.org/web/20090110162823/http://vulcan.wr.usgs.gov/Volcanoes/Philippines/Pinatubo/Publications/FireMud/about_the_book.html|url-status=live}}</ref> | |||
Scientists immediately installed monitoring equipment and analysed the volcano for clues as to its previous eruptive history. ] of charcoal found in old volcanic deposits revealed the three major explosive eruptions in recent millennia, about 5500, 3500 and 500 years ago. Geological mapping showed that much of the surrounding plains were formed by ] deposits from previous eruptions. | |||
====1991 eruption==== | |||
Volcanic activity increased throughout April and May. Measurements of ] emission showed a rapid increase from 500 ]s per day on ] to 5,000 tons/day by ]. This implied that there was a rising column of fresh ] beneath the volcano. After ], the amount of SO<sub>2</sub> being emitted decreased substantially, raising fears that the degassing of the magma had been blocked somehow, leading to a ] build-up in the ] and a high likelihood of explosive eruptions. | |||
{{Main|1991 eruption of Mount Pinatubo}} | |||
] of Mount Pinatubo on June 12, 1991, three days before the climactic eruption]] | |||
]s, and left a caldera in the former summit region. Later dubbed Black Saturday, the day of darkness stretched for 36 hours.]] | |||
A small blast at 03:41 PST on June 12 marked the beginning of a new, more violent phase of the eruption. A few hours later the same day, massive blasts lasting about half an hour generated big eruption columns, which quickly reached heights of over {{convert|19|km|ft}} and which generated large ]s extending up to {{convert|4|km|mi|spell=in}} from the summit in some river ]s. Fourteen hours later, a 15-minute blast hurled volcanic matter to heights of {{convert|24|km|mi|abbr=on}}. Friction in the up-rushing ash column generated abundant ]. | |||
In March and April 1991, magma rising toward the surface from more than {{convert|32|km|mi|abbr=on}} beneath Pinatubo triggered small ]s and caused powerful ] that blasted three ] on the north flank of the volcano. Thousands of small earthquakes occurred beneath Pinatubo through April, May and early June and many thousand of tons of noxious ] gas were also emitted by the volcano.<ref name="Pinatubo1991"/> | |||
The first ]tic eruptions occurred on ], and the first large explosion on ] generated an ash column 7 km (4.5 miles) high. The Philippine Institute of ] and ] (PHIVOLCS) led by ] issued a warning indicating the possibility of a major eruption within two weeks. | |||
From June 7 to 12, the first magma reached the surface of Mount Pinatubo. Because it had lost most of the gas contained in it on the way to the surface, the magma oozed out to form a lava dome but did not cause an explosive eruption. However, on June 12, millions of cubic yards of gas-charged magma reached the surface and exploded in the reawakening volcano's first spectacular eruption.<ref name="Pinatubo1991"/> | |||
===Evacuation=== | |||
] | |||
When even more highly gas-charged magma reached Pinatubo's surface on June 15, the volcano exploded in a cataclysmic eruption that ejected more than {{Convert|5|km3|mi3|abbr=on}} of material. The ] from this climactic eruption rose {{Convert|35|km|mi|abbr=on}} into the atmosphere. At lower altitudes, the ] was blown in all directions by the intense cyclonic winds of a coincidentally occurring typhoon, and winds at higher altitudes blew the ash southwestward. A blanket of ash and larger ] ] blanketed the countryside. Fine ash fell as far away as the ] and satellites tracked the ash cloud several times around the globe.<ref name="Pinatubo1991"/> | |||
Given all the signs that a very large eruption was imminent, PHIVOLCS worked in cooperation with the ] to convince people in the local area of the severity of the threat. A false warning might have led to cynicism about any later warnings but delaying a warning until an eruption began might lead to thousands of deaths, so the ] were under some pressure to deliver a timely and accurate assessment of the volcanic risk. | |||
Huge pyroclastic flows roared down the flanks of Mount Pinatubo, filling once-deep valleys with fresh volcanic deposits as much as {{Convert|200|m|ft|abbr=on}} thick. The eruption removed so much magma and rock from below the volcano that the summit collapsed to form a {{Convert|2.5|km|mi|abbr=on}} wide caldera.<ref name="Pinatubo1991"/> | |||
Three successive evacuation zones were defined, the innermost containing everything within 10 km of the volcano's summit, the second extending from 10 to 20 km from the summit, and the third extending from 20 to 40 km from the summit (] and ] were in this zone). The 10 km and 10–20 km zones had a total population of about 40,000, while some 331,000 people lived in the 20–40 km zone. Five stages of volcanic alert were defined, from level 1 (low level seismic disturbances) up to level 5 (major eruption in progress). Daily alerts were issued stating the alert level and associated danger area, and the information was announced in major national and local ]s, ] and ] stations, ]s (NGOs), and directly to the endangered inhabitants. | |||
Following the climactic eruption of June 15, 1991, activity at the volcano continued at a much lower level, with continuous ash eruptions lasting until August 1991 and episodic eruptions continuing for another month. | |||
Many of the Aeta who lived on the slopes of the volcano left their villages of their own volition when the first explosions began in April, gathering in a village about 12 km from the summit. They moved to increasingly distant villages as the eruptions escalated, with some Aeta moving up to nine times in the two months preceding the cataclysmic eruption. | |||
] | |||
The first formal evacuations were ordered from the 10 km zone on ]. Evacuation of the 10–20 km zone was ordered when a level 4 alert was issued on ]. A level 5 alert triggered evacuation of the 20–40 km zone on ], and in all some 60,000 people had left the area within 30 km of the volcano before ]. Most people temporarily relocated to ] and ], with some 30,000 using the ] in Quezon City as a ]. | |||
=== |
====Later eruptions==== | ||
] | ], the crater lake resulting from the 1991 eruption, pictured here in 2008]] | ||
Activity at the volcano remained low until July 1992 when a new lava dome started growing in the ]. Volcanologists suspected that further violent eruptions could be possible, and some areas were evacuated. However, the eruption was only minor. The last eruption of Mount Pinatubo took place in 1993.<ref name="SI"/> | |||
In early June, ] measurements had shown that the volcano was inflating, evidently due to growing amounts of magma filling the reservoir beneath the summit. At the same time, seismic activity, previously concentrated at a depth of a few kilometers below a point about 5 km northwest of the summit, shifted to shallow depths just below the summit. On ], the first magmatic eruptions took place with the formation of a ] at the summit of the volcano. The dome grew substantially over the next five days, reaching a maximum diameter of about 200 m and a height of 40 m. | |||
====Lake Pinatubo==== | |||
A small explosion at 03:41 on ] marked the beginning of a new, more violent phase of the eruption. A few hours later, large explosions lasting about half an hour generated an ] which quickly reached heights of over 19 km, and which generated ]s extending up to 4 km from the summit in some river ]s. Fourteen hours later, a 15 minute eruption hurled ash to heights of 24 km. Friction in the uprushing ash column generated abundant ]. | |||
{{Main|Lake Pinatubo}} | |||
] in 2006]] | |||
The 1991 caldera afterwards filled with water from annual monsoon rains and a ], ], was formed. In 1992, a growing lava dome formed an island, which was eventually submerged by the lake. Initially, the lake was hot and highly ]ic, with a minimum ] of 2 and a temperature of about {{convert|40|C|F}}. Subsequent rainfall cooled and diluted the lake, lowering the temperature to {{convert|26|C|F}} and raising the pH to 5.5 by 2003. | |||
The lake deepened by about {{convert|1|m|ft|sp=us}} per month on average, eventually submerging the lava dome, until September 2001, when fears that the walls of the crater might be unstable prompted the Philippine government to order a controlled draining of the lake. An estimated 9,000 people were once again evacuated from surrounding areas in case a large ] was accidentally triggered. Workers cut a {{convert|5|m|sp=us|adj=on}} notch in the crater rim and drained about a quarter of the lake's volume.<ref>{{cite news|date=September 7, 2001|url=http://news.bbc.co.uk/2/hi/asia-pacific/1530182.stm|title=Filipinos return as volcano lake drains|publisher=BBC News|access-date=May 25, 2010|archive-date=April 21, 2021|archive-url=https://web.archive.org/web/20210421010958/http://news.bbc.co.uk/2/hi/asia-pacific/1530182.stm|url-status=live}}</ref> | |||
A third large eruption began at 08:41 on ], after an intense swarm of small earthquakes over the previous two hours. It lasted about five minutes, and the eruption column once again reached 24 km. After three hours of quiet, seismic activity began, growing more and more intense over the next 24 hours, until a three-minute eruption generated a 21 km-high eruption column at 13:09 on ]. | |||
===Recent activity=== | |||
Tephra fall from these four large eruptions was extensive to the southwest of the volcano. Two hours after the last of these four explosions, a series of eruptions began which lasted for the next 24 hours, and which saw the production of much larger pyroclastic flows and surges which travelled several kilometres down river valleys on the flanks of the volcano. | |||
] | |||
On July 10, 2002, the west wall of the crater collapsed, slowly releasing approximately {{convert|160|e6m3|e9cuft|sp=us|}} of water and sediment into the Maraunot River in ].<ref>{{Cite web|url=http://glassiris.info/Timeline.php?srch=collapses|title=Timelines Page @ glassiris.info|website=glassiris.info|access-date=August 21, 2020|archive-date=December 18, 2014|archive-url=https://web.archive.org/web/20141218190006/http://glassiris.info/Timeline.php?srch=collapses|url-status=live}}</ref> | |||
] was the ] making up the tephra in these eruptions and in the following climactic event. The most abundant ] minerals were ] and ], but an unusual phenocryst mineral was also present—the calcium sulfate, ]. The dacite ] was more oxidized than most magmas, and sulfur-rich nature of the eruption probably was causally related to the ]. | |||
On July 26, 2011, a 5.9 magnitude earthquake struck close to Pinatubo; however, no major damages or casualties were reported.<ref>Gonzaga, Robert and Orejas, Tonette (July 26, 2011). {{Webarchive|url=https://web.archive.org/web/20110813194932/http://newsinfo.inquirer.net/30559/5-9-magnitude-quake-jolts-households-in-luzon-metro-areas |date=August 13, 2011 }}. Inquirer News.</ref> | |||
===The climactic eruption=== | |||
] | |||
On March 4, 2021, the PHIVOLCS raised alert level 1 over Mount Pinatubo after reporting an increase on its seismic activity. 1,722 volcanic earthquakes were also recorded within the vicinity of the volcano since January 2021.<ref>{{Cite web|url=https://www.gmanetwork.com/news/scitech/science/778262/alert-level-1-raised-in-mt-pinatubo/story/|title=Alert Level 1 raised in Mt. Pinatubo —PHIVOLCS|website=GMA News Online|access-date=March 4, 2021|archive-date=March 4, 2021|archive-url=https://web.archive.org/web/20210304050835/https://www.gmanetwork.com/news/scitech/science/778262/alert-level-1-raised-in-mt-pinatubo/story/|url-status=live}}</ref> | |||
] saw the onset of the climactic ]. Large tremors starting at 13:42 saturated all the seismographs at ], and by 14:30 all had been rendered inoperative, mostly by pyroclastic density currents. Intense ] pressure variation was also recorded. | |||
On August 11, 2021, PHIVOLCS downgraded Mt. Pinatubo's Alert Level 1 to Level 0, due to "continued decrease in earthquake activity and a return to baseline seismic parameters". | |||
On the same day, ] struck the island, passing about 75 km (50 miles) ] of the volcano. The typhoon rains made direct visual observations of the eruption impossible, but measurements showed that ash was ejected to heights of 34 km by the most violent phase of the eruption, which lasted about three hours. ]s poured from the summit, reaching as far as 16 km away from it. ] rains mixed with the ash deposits caused massive ]. | |||
PHIVOLCS said it noted a "significant decrease" in volcanic earthquakes, with a total of 104 quakes or an average 2–3 events per day recorded from July 1 – August 1, 2021.<ref>{{Cite web|last=Ramos|first=Christia Marie|date=August 12, 2021|title=Phivolcs lifts Mt. Pinatubo alert level|url=https://newsinfo.inquirer.net/1472571/phivolcs-lifts-alert-level-off-mt-pinatubo|access-date=August 15, 2021|website=INQUIRER.net|language=en|archive-date=August 15, 2021|archive-url=https://web.archive.org/web/20210815115034/https://newsinfo.inquirer.net/1472571/phivolcs-lifts-alert-level-off-mt-pinatubo|url-status=live}}</ref> | |||
The ash cloud from the volcano covered an area of some ] (50,000 mi²), bringing total darkness to much of central Luzon. Almost all of the island received some ashfall, which formed a heavy, rain-saturated snow-like blanket. ] fell over most of the ] and ashfall was recorded as far away as ], ] and ]. | |||
On November 30, 2021, PHIVOLCS reported a weak explosion occurred on Mt. Pinatubo between 12:09 p.m. and 12:13 p.m., which produced a plume.<ref>{{Cite news|date=November 30, 2021|title='Weak explosion' recorded on Mt. Pinatubo but no magma activity – Phivolcs|url=https://news.abs-cbn.com/news/11/30/21/weak-explosion-recorded-on-mt-pinatubo|access-date=November 30, 2021|work=ABS-CBN News|language=en|archive-date=November 30, 2021|archive-url=https://web.archive.org/web/20211130115457/https://news.abs-cbn.com/news/11/30/21/weak-explosion-recorded-on-mt-pinatubo|url-status=live}}</ref> The agency later confirmed it was a phreatic explosion produced by ] fluids near the surface, rather than a magmatic eruption.<ref>{{Cite news|date=November 30, 2021|title=PHIVOLCS confirms Mount Pinatubo phreatic eruption|url=https://www.gmanetwork.com/news/scitech/science/812825/phivolcs-confirms-mount-pinatubo-phreatic-eruption/story/|access-date=November 30, 2021|work=GMA News|language=en|archive-date=November 30, 2021|archive-url=https://web.archive.org/web/20211130121903/https://www.gmanetwork.com/news/scitech/science/812825/phivolcs-confirms-mount-pinatubo-phreatic-eruption/story/|url-status=live}}</ref> | |||
By about 22:30, nine hours after the onset of the climactic phase, atmospheric pressure waves had decreased to the pre-eruption levels. No seismic records were available at this time, but volcanologists believe 22:30 marked the end of the climactic eruption. | |||
==Cultural history== | |||
Vast quantities of minerals and metals were brought to the surface. Overall, introduced to the surface environment, was an estimated 800,000 tons of ], 600,000 tons of ], 550,000 tons of ], 300,000 tons of ], 100,000 tons of ], 10,000 tons of ], 1000 tons of ], & 800 tons of ].<ref>Garret, R.G. (2000) Natural sources of metals in the environment. Human and Ecological Risk Assessment., (6), 945–963.</ref> | |||
The word ''pinatubo'' could mean "fertile place where one can make crops grow", or could mean "made to grow", in ] and ], which may suggest a knowledge of its previous eruption in about 1500 AD. There is a local oral tradition suggestive of a folk memory of earlier large eruptions. An ancient legend tells of Bacobaco, a terrible spirit of the sea, who could metamorphose into a huge turtle and throw fire from his mouth. In the legend, when being chased by the spirit hunters, Bacobaco flees to the mountain and digs a great hole in its summit showering the surrounding land with rock, mud, dust and fire for three days; howling so loudly that the earth shakes.<ref>Rodolfo, K.S. & Umbal, J.V. (2008) "A prehistoric lahar-dammed lake and eruption of Mount Pinatubo described in a Philippine aborigine legend", J. Volcanol. Geotherm. Res., '''176''', 432–437</ref> | |||
=== |
===History among Aetas=== | ||
] elders tell many stories about the history of the mountain, the best known being that it was once a Batung Mabye (] for "living stone"). It was said to have been planted on a kingdom by a displeased sorcerer but relocated by a hero. The mountain was soon turned into the abode of Apo Namalyari ("The lord of happenings/events"), the pagan deity of the ], Aetas and ] living on the Zambales range.<ref name="hau.edu.ph">{{cite journal|url=http://www.hau.edu.ph/kapampangan_center/publication/pdf/singsing/rivers.pdf|title=Kampangan Folk : The Power and the Glory|journal=Singsing|volume=3|issue=2|issn=1655-6305|access-date=July 4, 2013|archive-date=November 10, 2013|archive-url=https://web.archive.org/web/20131110133354/http://www.hau.edu.ph/kapampangan_center/publication/pdf/singsing/rivers.pdf|url-status=live}}</ref> | |||
] | |||
It was said to comprise the whole mountain range until Sinukuan of ] (the god of the Kapampangans) became a strong rival of Namalyari. Their fight, which took place over the center plains, shattered the mountain into smaller bodies and Mount Arayat lost its center peak. Other versions have it that Pinatubo's peak shattered because of Namalyari's immense fury in an attempt to teach humans the meaning of fear and show how misdeeds will be punished.<ref name="hau.edu.ph"/> | |||
In all, the eruption ejected about ten cubic kilometres (2.5 mile³) of material, making it the largest eruption since that of ] in 1912 and some ten times larger than the ]. Ejected material such as ] fallout and pyroclastic flow deposits are much less dense than magma, and the volume of ejected material was equivalent to about four cubic kilometres (1 mile³) of unerupted material. This colossal eruption had a ] of 6.<ref>{{Citation | |||
|url=http://www.ngdc.noaa.gov/seg/hazard/stratoguide/pinfact.html | |||
|title=Mt. Pinatubo, Luzon, Philippines | |||
|publisher=National Geophysical Data Center (U.S. NOAA) | |||
|accessdate=2007-12-02}}</ref> The former summit of the volcano was replaced by a ] 2.5 km wide. The highest point on the caldera rim now stood 1,485 m above sea level, some 260 m lower than the pre-eruption summit. | |||
According to the native elders, Apo Namalyari induced the June 1991 eruption because of displeasure toward illegal loggers and ] executives who performed deep exploratory drilling and well testing on the volcano looking for geothermal heat from 1988 to 1990.<ref>{{cite news|url=https://archive.seattletimes.com/archive/19910721/1295627/natives-who-worship-pinatubo-feel-its-wrath|title=Natives Who Worship Pinatubo Feel Its Wrath|last=Loeb|first=Vernon|date=July 21, 1991|work=]|access-date=November 22, 2008|archive-date=November 18, 2011|archive-url=https://web.archive.org/web/20111118142836/http://community.seattletimes.nwsource.com/archive/?date=19910721&slug=1295627|url-status=live}}</ref> Discouraging results from the wells forced the abandonment of the prospect 13 months before the April 2, 1991, explosions.<ref>Delfin Jr., F.G., Villarosa, H.G.. {{Webarchive|url=https://web.archive.org/web/20111118142708/http://pubs.usgs.gov/pinatubo/delfin/index.html |date=November 18, 2011 }}. USGS. Retrieved on August 14, 2011.</ref> | |||
About 300 people were killed by the eruption, mostly by roofs collapsing under the weight of accumulated wet ash, a hazard that was greatly exacerbated by the simultaneous arrival of Typhoon Yunya. The evacuation in the days preceding the eruption certainly saved tens of thousands of lives, and has been hailed as a great success for volcanology and eruption prediction. | |||
==Aetas granted ownership of Pinatubo== | |||
] deposits]] | |||
After being driven away by the 1991 eruption of Mount Pinatubo, in May 2009 some 454 Aeta families in Pampanga were given the first clean ancestral land ownership on Mount Pinatubo with the Certificate of Ancestral Domain Title (CADT) by the ] (NCIP), the government agency that deals with issues concerning indigenous people of the Philippines. The approved and declared net land area of {{convert|7440.1|ha|acre|abbr=on}} covers the ]s of Mawakat and Nabuklod in ], plus a portion of ], and a portion of Barangay Batiawan in ].<ref>(2009-05-27). {{Webarchive|url=https://web.archive.org/web/20160306115943/https://www.scribd.com/doc/35827181/Aetas-in-Pampanga-Awarded-Land-Title |date=March 6, 2016 }}. Scribd. Retrieved on August 14, 2011.</ref> | |||
On January 14, 2010, some 7,000 Aeta families from Zambales were officially granted the Certificate of Ancestral Domain Title (CADT) covering the Zambales side of Pinatubo which includes the summit and Lake Pinatubo, officially becoming their ''lutan tua'' (ancestral land). The ancestral domain title covers {{convert|15984|ha|acre|abbr=on}} and includes the villages of Burgos, Villar, Moraza and Belbel in Botolan and portions of the towns of ], ] and ].<ref>Orejas, Tonette (November 27, 2009). {{webarchive|url=https://web.archive.org/web/20111118144033/http://www.piplinks.org/it%E2%80%99s-official%3A-pinatubo-now-owned-aetas |date=November 18, 2011 }}. PIPLinks (originally from '']''). Retrieved on August 14, 2011.</ref><ref name="Preda"/> | |||
However, since the eruption, each ] has brought further ], which have caused the displacement of thousands of people. Hundreds have died from poor ] in relocation camps. ] in the region also suffered badly from the effects of the eruption, with hundreds of square kilometres of formerly ] land being rendered infertile, destroying the livelihoods of thousands of farmers. | |||
Ancestral domain titles are awarded to a certain community or indigenous group who have occupied or possessed the land continuously in accordance with their customs and traditions since time immemorial. They have the legal right to collectively possess and to enjoy the land and its natural resources to the exclusion of others.<ref name="Preda"/> Having the land title will protect them from others – including foreigners – exploiting their land without compensation to and consent from the indigenous tribes. In the past, the Aetas had to contend with mining companies, loggers, and recently, tourist companies who earn from Mount Pinatubo but do not compensate the local tribes.<ref name="Preda">Valdez, Katrina Mennen A. (January 14, 2010). {{webarchive|url=https://archive.today/20130415191840/http://www.preda.org/main/archives/2010/r10011401.html |date=April 15, 2013 }}. ]. Retrieved on August 14, 2011.</ref> | |||
The ] maintained two large military bases in the region; ] was 75 km (50 mi.) to the southwest, while ] was less than 25 km (16 mi.) to the east of the volcano's summit. Both were abandoned after being severely damaged by the eruption. | |||
==In popular culture== | |||
Although the 1991 eruption was one of the largest and most violent of the 20th century, it was weaker than any of the historical eruptions uncovered by geologists. There is some evidence that eruptions at Pinatubo are getting weaker over time, but this is by no means conclusively established. | |||
] | |||
Long before Mount Pinatubo became famous for its cataclysmic eruption, ] ], a native of Zambales, named his ] ] ''Mt. Pinatubo''. The ] into ] in ] in 1957, killing the president and twenty-four others on board.<ref>{{cite news|author=Dominico C. Moneva|title=Speak out: Magsaysay's death|url=http://www.sunstar.com.ph/static/ceb/2006/03/18/oped/dominico.c..moneva..html|work=SunStar Cebu|date=March 18, 2006|access-date=March 21, 2008|archive-url=https://web.archive.org/web/20080517202331/http://www.sunstar.com.ph/static/ceb/2006/03/18/oped/dominico.c..moneva..html|archive-date=May 17, 2008|url-status=dead}}</ref> | |||
The shape of Mount Pinatubo's caldera inspired ] in ], ].<ref>{{cite news|last1=Enriquez|first1=Marge|title=Design duo tapped to build 'city of the future'|url=http://lifestyle.inquirer.net/283590/design-duo-tapped-build-city-future/|access-date=March 9, 2018|newspaper=Philippine Daily Inquirer|date=January 3, 2018|archive-date=December 1, 2020|archive-url=https://web.archive.org/web/20201201183631/https://lifestyle.inquirer.net/283590/design-duo-tapped-build-city-future/|url-status=live}}</ref> | |||
===Local economic and social effects=== | |||
] destroyed by ashfall]] | |||
==Hiking activity== | |||
The eruption of Pinatubo severely hampered the ] of the surrounding areas. Extensive damage to buildings and ] cost billions of ]s to repair, and further costs were incurred in constructing ] and ]s to control the post-eruption lahars. | |||
The caldera formed and ] has, since June 15, 1991, become a tourist attraction with the preferred route through Barangay Santa Juliana in ].<ref>{{cite news|title=Trekking-Mt-Pinatubo|newspaper=Philippine Daily Inquirer|url=http://lifestyle.inquirer.net/2bu/2bu/view/20100529-272636/Trekking-Mt-Pinatubo|access-date=June 13, 2012|date=May 29, 2010|url-status=dead|archive-url=https://web.archive.org/web/20121114015117/http://lifestyle.inquirer.net/2bu/2bu/view/20100529-272636/Trekking-Mt-Pinatubo|archive-date=November 14, 2012}}</ref> | |||
==Biodiversity== | |||
In total, 364 communities and 2.1 million people were affected by the eruption, with livelihoods and houses being damaged or destroyed. More than 8,000 houses were completely destroyed, and a further 73,000 were damaged. In addition to the severe damage sustained by these communities, roads and communications were damaged or destroyed by pyroclastic flows and lahars throughout the areas surrounding the volcanoes. The estimated cost of repairing the damage to infrastructure was 3.8 billion pesos. | |||
===Mammals=== | |||
Many ] projects were destroyed in the eruption, with a total area of 150 square kilometres (37,000 ]s) valued at 125 million pesos destroyed. ] was heavily disrupted, with 800 square kilometres (200,000 acres) of ]-growing farmland destroyed, and almost 800,000 head of livestock and ] killed. The cost to agriculture of eruption effects was estimated to be 1.5 billion pesos. | |||
The '''Long-nosed forest mouse''' (]) is a species of ] endemic to Mount Pinatubo, Philippines.<ref name="0006-324X-126-4-395">{{cite journal |last1=Heaney |first1=Lawrence R. |last2=Balete |first2=Danilo S. |last3=Veluz |first3=Maria Josefa |last4=Steppan |first4=Scott J. |last5=Esselstyn |first5=Jacob A. |last6=Pfeiffer |first6=Andrew W. |last7=Rickart |first7=Eric A. |title=Two new species of Philippine forest mice (''Apomys'', Muridae, Rodentia) from Lubang and Luzon Islands, with a redescription of ''Apomys sacobianus'' Johnson, 1962 |journal=Proceedings of the Biological Society of Washington |date=January 2014 |volume=126 |issue=4 |pages=395–413 |doi=10.2988/0006-324X-126.4.395 |s2cid=49347286 }}</ref> | |||
Damage to ] facilities, and the spread of illnesses in relocation facilities, led to soaring death rates in the months following the eruption. ] for thousands of children was seriously disrupted by the destruction of ]s in the eruption. The gross regional domestic product of the Pinatubo area accounted for about 10% of the total Philippine ]. The GRDP had been growing at 5% annually before the eruption, but fell by more than 3% from 1990 to 1991. | |||
The '''Zambales forest mouse''' (]) is a species of ] endemic to ], Philippines.<ref name="0006-324X-126-4-395">{{cite journal |last1=Heaney |first1=Lawrence R. |last2=Balete |first2=Danilo S. |last3=Veluz |first3=Maria Josefa |last4=Steppan |first4=Scott J. |last5=Esselstyn |first5=Jacob A. |last6=Pfeiffer |first6=Andrew W. |last7=Rickart |first7=Eric A. |title=Two new species of Philippine forest mice (''Apomys'', Muridae, Rodentia) from Lubang and Luzon Islands, with a redescription of ''Apomys sacobianus'' Johnson, 1962 |journal=Proceedings of the Biological Society of Washington |date=January 2014 |volume=126 |issue=4 |pages=395–413 |doi=10.2988/0006-324X-126.4.395 |s2cid=49347286 }}</ref> | |||
===Global environmental effects=== | |||
]) photograph of the Earth over ] taken on ], ], showing double layer of Pinatubo aerosol cloud (dark streaks) above high cumulonimbus tops]] | |||
==See also== | |||
The powerful eruption of such an enormous volume of lava and ash injected significant quantities of ] and ] into the ]. ] oxidised in the atmosphere to produce a haze of ] droplets, which gradually spread throughout the stratosphere over the year following the eruption. The injection of aerosols into the stratosphere is thought to have been the largest since the eruption of ] in ], with a total mass of SO<sub>2</sub> of about 17 million tons being injected—the largest volume ever recorded by modern instruments (see ] and ]). | |||
{{Portal|Volcanoes|Philippines}} | |||
*] | |||
This very large stratospheric injection resulted in a reduction in the normal amount of ] reaching the earth's surface by up to 5% (see ]). This led to a decrease in ] average temperatures of 0.5–0.6 °] (0.9–1.1 °F), and a global fall of about 0.4 °C (0.7 °F). At the same time, the temperature in the stratosphere rose to several degrees higher than normal, due to absorption of radiation by the aerosols. The stratospheric cloud from the eruption persisted in the atmosphere for three years after the eruption. | |||
**] | |||
**] | |||
] emissions from Mount Pinatubo.]] | |||
**] | |||
* ] | |||
The eruption had a significant effect on ] levels in the atmosphere, causing a large increase in the destruction rate of ozone. Ozone levels at mid-latitudes reached their lowest recorded levels, while in the ] winter of 1992, the ] over ] reached its largest ever size until then, with the fastest recorded ozone depletion rates. The eruption of ] in ] in August 1991 also contributed to southern hemisphere ozone destruction, with measurements showing a sharp decrease in ozone levels at the ] when the aerosol clouds from Pinatubo and Hudson arrived. | |||
* ] | |||
{{Clear}} | |||
Another noticeable effect of the dust in the atmosphere was the appearance of ]s. Normally even at mid-eclipse, the moon is still visible although much dimmed, but in the year following the Pinatubo eruption, the moon was hardly visible at all during eclipses, due to much greater absorption of sunlight by dust in the atmosphere. | |||
<!-- commenting this out for now, don't trust this source but am looking for papers which might back this up. | |||
It has also been suggested that excess ] from the eruption were responsible for the "]" in the ]<ref></ref>--> | |||
===The area since 1991=== | |||
]]] | |||
Following the climactic eruption of ], ], activity at the volcano continued at a much lower level, with continuous ash eruptions lasting until August 1991 and episodic eruptions continuing for another month. Activity then remained low until July 1992, when a new ] began to grow in the ]. | |||
This dome appeared to be composed of fresh lava from the deep ] reservoir beneath the volcano, rather than material 'left over' in a shallow reservoir from the 1991 eruption. Thus, volcanologists suspected that further violent eruptions could be possible, and some areas were once again evacuated. However, the eruption did not become violent, perhaps due to outgassing from the deep reservoir reducing the explosivity of the lava reaching the surface. Since 1992, the volcano has been dormant. | |||
The Aeta people were the hardest hit by the eruption. The total destruction of many villages by pyroclasts and lahar deposits meant that many Aeta were unable to return to their former way of life. After the areas surrounding the volcano were declared safe to return to, those whose villages had not been destroyed moved back, but most people moved instead to government-organized resettlement areas. Conditions on these were poor, with each family receiving only small plots of land, which were not ideal for growing crops. Many Aeta found casual labor working for lowland ]s, and overall Aeta society became much more fragmented, and reliant on and integrated with lowland culture. | |||
After eruptions ended, a ] formed in the 1991 caldera, with the 1992 lava dome forming an ]. At first, the lake was small, hot and highly ]ic, with a minimum ] of 2 and a temperature of about 40 °C. Abundant rainfall cooled and diluted the lake, lowering the temperature to 26 °C and raising the pH to 5.5 by 2003. | |||
The lake increased in depth by about 1 metre per month on average, until September 2001, when fears that the walls of the crater might be unstable prompted the Philippine government to order a controlled draining of the lake. 9,000 people were once again evacuated from surrounding areas in case a large ] was accidentally triggered. Workers cut a 5 m notch in the crater rim, and successfully drained about a quarter of the lake's volume. | |||
==Ecotourism== | |||
As of 2007, Mt. Pinatubo is a popular tourist destination in Central Luzon. Tour operators offer a whole-day package which includes a 4x4 jeep ride that starts off at ], taking tourists across the barren plains. A 2-3 hour trek then commences on a trail that leads to the crater lake. There, facilities include a viewdeck, cottages, and kayaks. Swimming in the lake is allowed although it is restricted to the proximal banks.<ref name="pinoymountaineer">{{Citation | last= | first= | author-link= | title=PinoyMountaineer: Mount Pinatubo | date= 24 August 2007 | year=2007 | url=http://www.pinoymountaineer.com/2007/08/mt-pinatubo-960.html | accessdate=26 October 2007 }}</ref> | |||
==Related images== | |||
<center><gallery> | |||
Image:pinatubo(052005).jpg|Mount Pinatubo and crater lake, May 2005 | |||
Image:TOMS SO2 Jun17 91.gif|] emissions. | |||
Image:Mauna Loa atmospheric transmission.png|] reduction due to volcanic eruptions. | |||
Image:TOMS SO2 time nov03.png|] emissions by ]es. | |||
Image:PinatuboLake.jpg|The Pinatubo crater lake in January 2006 | |||
Image:MajorVolcanoesOfThePhilippines-USGS.gif|Map showing major volcanoes of the Philippines | |||
</gallery></center> | |||
{{commonscat|Mount Pinatubo}} | |||
==Notes== | ==Notes== | ||
{{reflist |
{{reflist}} | ||
==References== | ==References== | ||
{{Refbegin}} | |||
* {{cite journal|vauthors=Chakraborty P, etal|year=2009|title=Volcanic mesocyclones|journal=Nature|volume=458|issue=7237|pages=495–500|url=http://web.mechse.illinois.edu/research/gioia/Art/nature07866.pdf|doi=10.1038/nature07866|bibcode=2009Natur.458..497C|pmid=19325632|s2cid=1129142}}{{dead link|date=December 2017 |bot=InternetArchiveBot |fix-attempted=yes }} | |||
* Decker, R. and Decker, B. (1997) ''Volcanoes'', 3rd edition, WH Freeman, New York. | * Decker, R. and Decker, B. (1997) ''Volcanoes'', 3rd edition, WH Freeman, New York. | ||
* {{cite journal|author=McCormick, M. Patrick|year=1995|title=Atmospheric effects of the Mt Pinatubo eruption|journal=]|volume=373|issue=6513|pages=399–404|doi=10.1038/373399a0|bibcode=1995Natur.373..399M|s2cid=46437912|display-authors=etal}} | |||
* Hiromu Shimizu (2002), ''''. Paper presented inter-congress of the International Union of Anthropological and Ethnological Sciences, Tokyo, Japan. | |||
* {{cite book|title=Geological Disasters In The Philippines: The July 1990 Earthquake And The June 1991 Eruption of Mount Pinatubo. Description, effects and lessons learned|last=Rantucci|first=Giovanni|year=1994|publisher=Philippine Institute of Volcanology and Seismology (PHIVOLCS)|isbn=978-0-7881-2075-6|url=https://books.google.com/books?id=qK3uy9oMzccC|access-date=August 15, 2009|archive-date=August 6, 2020|archive-url=https://web.archive.org/web/20200806023840/https://books.google.com/books?id=qK3uy9oMzccC|url-status=live}} | |||
*{{cite journal | author = McCormick, M. Patrick et al. | year = 1995 | title = Atmospheric effects of the Mt Pinatubo eruption | journal = ] | volume = 373 | pages = 399–404 | doi = 10.1038/373399a0 }} | |||
* {{cite book|last=Reilly|first=Benjamin|title=Disaster and human history: case studies in nature, society and catastrophe|url=https://books.google.com/books?id=mI77lmwmVDkC|year=2009|publisher=McFarland|isbn=978-0-7864-3655-2|access-date=September 24, 2016|archive-date=January 3, 2014|archive-url=https://web.archive.org/web/20140103123244/http://books.google.com/books?id=mI77lmwmVDkC|url-status=live}} | |||
* Newhall, C. and ], R., eds. (1997) ''''. ISBN 0-295-97585-7. | |||
* {{Cite book|author1=Self S.|author2=Zhao, Jing-Xia|author3=Holasek, R.E.|author4=Torres, R.C.|author5=King, A.J.|year=1998|quote=The atmospheric impact of the 1991 Mount Pinatubo eruption|title=Fire and Mud, Eruptions and Lahars of Mount Pinatubo, Philippines|editor1=Newhall, C.G.|editor2=Punongbayan, R.S.|publisher=Smithsonian Institution – Global Volcanism Program|place=Washington|page=1126|url=http://pubs.usgs.gov/pinatubo/self/index.html|access-date=April 21, 2010|archive-date=November 17, 2017|archive-url=https://web.archive.org/web/20171117014144/https://pubs.usgs.gov/pinatubo/self/index.html|url-status=live}} | |||
* Scaillet, B. and Evans, B. W. (1999) ''The 15 June 1991 Eruption of Mount Pinatubo. I. Phase Equilibria and Pre-eruption P–T–fO2–fH2O Conditions of the Dacite Magma.'' Journal of Petrology, v. 40, 381–411. | |||
* {{cite journal|doi=10.1093/petroj/40.3.381|title=The 15 June 1991 Eruption of Mount Pinatubo. I. Phase Equilibria and Pre-eruption P-T-fO2-fH2O Conditions of the Dacite Magma|year=1999|last1=Scaillet|first1=B.|last2=Evans|first2=B. W.|journal=Journal of Petrology|volume=40|issue=3|pages=381–411|bibcode=1999JPet...40..381S|doi-access=free}} | |||
* Stimac J.A., Goff F., Counce D., Larocque A.C.L., Hilton D.R. (2003), ''The crater lake and hydrothermal system of Mount Pinatubo, Philippines: evolution in the decade after eruption'', Bulletin of Volcanology, v. 66, p. 149–167 | |||
* {{cite journal|doi=10.1007/s00445-003-0300-3|title=The crater lake and hydrothermal system of Mount Pinatubo, Philippines: Evolution in the decade after eruption|year=2004|last1=Stimac|first1=James A.|last2=Goff|first2=Fraser|last3=Counce|first3=Dale|last4=Larocque|first4=Adrienne C. L.|last5=Hilton|first5=David R.|last6=Morgenstern|first6=Uwe|journal=Bulletin of Volcanology|volume=66|issue=2|pages=149–167|bibcode=2004BVol...66..149S|s2cid=128408824}} | |||
* Wiesner, M.G., Wetzel, A. Catane, S.G., Listanco, E.L. and Mirabueno, H.T. (2004) Grain size, areal thickness distribution and controls on sedimentation of the 1991 Mount Pinatubo tephra layer in the South China Sea. Bulletin of Volcanology, v. 66, 226–242. | |||
* {{cite journal|doi=10.1007/s00445-003-0306-x|title=Grain size, areal thickness distribution and controls on sedimentation of the 1991 Mount Pinatubo tephra layer in the South China Sea|year=2004|last1=Wiesner|first1=Martin G.|last2=Wetzel|first2=Andreas|last3=Catane|first3=Sandra G.|last4=Listanco|first4=Eddie L.|last5=Mirabueno|first5=Hannah T.|journal=Bulletin of Volcanology|volume=66|issue=3|pages=226–242|bibcode=2004BVol...66..226W|s2cid=128818475}} | |||
* Dhot, S. Mt Pinatubo Safety. | * Dhot, S. Mt Pinatubo Safety. | ||
{{Refend}} | |||
==External links== | ==External links== | ||
{{Commons category}} | |||
{{Spoken Misplaced Pages|Mount_Pinatubo.ogg|2006-01-31}} | |||
{{Spoken Misplaced Pages|Mount_Pinatubo.ogg|date=January 31, 2006}} | |||
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* , ] site | |||
* | |||
* | * EOS Volcanology. | ||
* . United States Geological Survey site | |||
* | |||
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* in the Smithsonian Institution's Global Volcanism Program (GVP) | |||
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Latest revision as of 19:48, 14 December 2024
Active stratovolcano in Luzon, Philippines "Pinatubo" redirects here. For the horse, see Pinatubo (horse).
Mount Pinatubo | |
---|---|
Mount Pinatubo crater lake in 2012 | |
Highest point | |
Elevation |
|
Listing | Active volcanoes in the Philippines |
Coordinates | 15°08′30″N 120°21′00″E / 15.14167°N 120.35000°E / 15.14167; 120.35000 |
Naming | |
Language of name | Tagalog |
Pronunciation | /ˌpiːnəˈtuːboʊ/ |
Geography | |
Mount PinatuboLocation within the Philippines | |
Location | Luzon |
Country | Philippines |
Region | Central Luzon |
Provinces | |
Parent range | Zambales Mountains |
Geology | |
Rock age(s) | Between 635,000 ± 80,000 and 1.1 ± 0.09 million years |
Mountain type | Stratovolcano |
Volcanic arc | Luzon Volcanic Arc |
Last eruption | November 30, 2021 |
Mount Pinatubo is an active stratovolcano in the Zambales Mountains in Luzon in the Philippines. Located on the tripoint of Zambales, Tarlac and Pampanga provinces, most people were unaware of its eruptive history before the pre-eruption volcanic activity in early 1991. Dense forests, which supported a population of several thousand indigenous Aetas, heavily eroded and obscured Pinatubo.
Pinatubo is known for its VEI-6 eruption on June 15, 1991, the second-largest terrestrial eruption of the 20th century after the 1912 eruption of Novarupta in Alaska. The eruption coincided with Typhoon Yunya making landfall in the Philippines, which brought a dangerous mix of ash and rain to nearby towns and cities. Early predictions led to the evacuation of tens of thousands of people, saving many lives. The eruption severely damaged surrounding areas with pyroclastic surges, pyroclastic falls, and later, flooding lahars caused by rainwater re-mobilizing volcanic deposits. This destruction affected infrastructure and altered river systems for years. Minor dome-forming eruptions inside the caldera continued from 1992 to 1993.
The 1991 eruption had worldwide effects. It released roughly 10 billion tonnes (1.1×10 short tons) or 10 km (2.4 cu mi) of magma, bringing large amounts of minerals and toxic metals to the surface. It also released 20 million tonnes (22 million short tons) of SO
2. It ejected more particulate into the stratosphere than any eruption since Krakatoa in 1883. In the following months, aerosols formed a global layer of sulfuric acid haze. Global temperatures dropped by about 0.5 °C (0.9 °F) in the years 1991–1993, and ozone depletion temporarily increased significantly.
Geography
The volcano is about 87 kilometers (54 mi) northwest of Manila, the capital of the Philippines. Near Mount Pinatubo are former military bases that were maintained by the United States. The U.S. Naval Base Subic Bay was 37 kilometers (23 mi) south of Pinatubo, and the extent of Clark Air Base was just 14 kilometers (8.7 mi) east of the volcano's summit. The volcano is near to about 6 million people.
History
Even before the 1991 eruption, Mount Pinatubo had little topographic prominence: it was 1,745 m (5,725 ft) above sea level, only about 600 m (2,000 ft) above nearby plains, and only about 200 m (660 ft) higher than surrounding peaks, which largely obscured it from view. It is part of a chain of volcanoes which lie along the western side of the island of Luzon called the Zambales Mountains.
Pinatubo belongs to the Cabusilan sub-range of the Zambales Mountains, which consists of Mount Cuadrado, Mount Negron, Mount Mataba and Mount Pinatubo. They are subduction volcanoes, formed by the Eurasian plate sliding under the Philippine Mobile Belt along the Manila Trench to the west. Mount Pinatubo and the other volcanoes on this volcanic belt arise due to magmatic occlusion from this subduction plate boundary.
Pinatubo is flanked on the west by the Zambales Ophiolite Complex, which is an easterly-dipping section of Eocene oceanic crust uplifted during the late Oligocene. The Tarlac Formation north, east and southeast of Pinatubo consists of marine, nonmarine and volcanoclastic sediments formed in the late Miocene and Pliocene.
The most recent study of Mount Pinatubo before the activities of 1991 was the overall geological study in 1983 and 1984 made by F. G. Delfin for the Philippine National Oil Company as part of the surface investigations of the area before exploratory drilling and well testing for geothermal energy sources in 1988 to 1990. He recognized two life histories of the mountain, which he classified as "ancestral" and "modern" Pinatubo.
Ancestral Pinatubo
Activity of Ancestral Pinatubo seems to have begun about 1.1 million years ago and probably ended tens of thousands of years or more before the birth of "modern" Pinatubo. Much of the rugged land around the present volcano consists of remnants of "ancestral" Pinatubo. It was an andesite and dacite stratovolcano whose eruptive activity was much less explosive than modern Pinatubo. Its center was roughly where the current volcano is. The projected height of the mountain is up to 2,300 m (7,500 ft), or 1.43 miles above sea level if it were a lone peak, based on a profile fitting to the remaining lower slopes, or lower if it had more than one peak.
The old volcano is exposed in the walls of an old 3.5 km × 4.5 km (2.2 mi × 2.8 mi) wide caldera, referred to as Tayawan Caldera by Delfin. Some of the nearby peaks are the remnants of ancestral Pinatubo, left behind when the softer parts of the old mountain slopes were eroded by weathering. Ancestral Pinatubo is a somma volcano with modern Pinatubo as the new cone. Mount Dorst, to the east, is part of the dip slope of the ancestral Pinatubo. Several mountains near modern Pinatubo are old satellite vents of ancestral Pinatubo, forming volcanic plugs and lava domes. These satellite vents were probably active around the same time as the ancestral volcano and include the domes of Mount Negron, Mount Cuadrado, Mount Mataba and the Bituin and Tapungho plugs.
Modern Pinatubo
- c. 79,000 BC: After a long period of dormancy, Modern Pinatubo was born in Ancestral Pinatubo's cataclysmic and most explosive eruptions, estimated to be five times larger than the June 1991 eruption. It deposited all around the volcano up to 25 km (6.0 cu mi) of pyroclastic surge material up to 100 meters (330 ft) thick. The total volume of volcanic material ejected during the eruptions is unknown. The removal of so much material from the underlying magma chamber resulted in the Tayawan caldera. The violent eruptive period started by the eruption is referred to by Delfin as the Inararo Eruptive Period, named after a village that was destroyed in the 1991 eruption.
Later eruptions of modern Pinatubo occurred episodically and lasted for periods much shorter than the repose intervals between them. Subsequent eruptions and eruptive period occurred about:
- c. 15,000 BC (Sacobia Eruptive Period)
- c. 7000 BC (Pasbul Eruptive Period). Its eruptions were as energetic, if not as voluminous as the Inararo eruptions.
- c. 4000–3000 BC (Crow Valley Eruptive Period). This and the Mara-unot period's eruptions were smaller than the Inararo eruptions but about two to three times as big as that of 1991 based on the pyroclastic flow runout distances and depths of valley filling.
- c. 1900–300 BC (Maraunot Eruptive Period)
- c. AD 1500 (Buag Eruptive Period). Its eruptions were roughly the same size as those of 1991.
Each of these eruptions seems to have been very large, ejecting more than 10 km (2.4 cu mi) of material and covering large parts of the surrounding areas with pyroclastic flow deposits. Some eruptive periods have lasted decades and perhaps as much as several centuries and might appear to include multiple large explosive eruptions.
The maximum size of eruptions in each eruptive period though has been getting smaller through the more than 35,000-year history of modern Pinatubo, but this might be an artifact of erosion and burial of older deposits. The oldest eruption of modern Pinatubo, Inararo, was also its largest.
The 1991 eruption was among the smallest documented in its geologic record.
The volcano has never grown very large between eruptions, because it produces mostly unwelded, easily erodible deposits and periodically destroys the viscous domes that fill its vents. After the Buag eruption (c. 1500 AD), the volcano lay dormant, its slopes becoming completely covered in dense rainforest and eroded into gullies and ravines. The c. 500-year repose though between the Buag and present eruptive periods is among the shorter repose periods recognized in its geologic history.
1991 eruption
Main article: 1991 eruption of Mount PinatuboA small blast at 03:41 PST on June 12 marked the beginning of a new, more violent phase of the eruption. A few hours later the same day, massive blasts lasting about half an hour generated big eruption columns, which quickly reached heights of over 19 kilometres (62,000 ft) and which generated large pyroclastic surges extending up to four kilometres (2.5 mi) from the summit in some river valleys. Fourteen hours later, a 15-minute blast hurled volcanic matter to heights of 24 km (15 mi). Friction in the up-rushing ash column generated abundant volcanic lightning.
In March and April 1991, magma rising toward the surface from more than 32 km (20 mi) beneath Pinatubo triggered small volcano tectonic earthquakes and caused powerful steam explosions that blasted three craters on the north flank of the volcano. Thousands of small earthquakes occurred beneath Pinatubo through April, May and early June and many thousand of tons of noxious sulfur dioxide gas were also emitted by the volcano.
From June 7 to 12, the first magma reached the surface of Mount Pinatubo. Because it had lost most of the gas contained in it on the way to the surface, the magma oozed out to form a lava dome but did not cause an explosive eruption. However, on June 12, millions of cubic yards of gas-charged magma reached the surface and exploded in the reawakening volcano's first spectacular eruption.
When even more highly gas-charged magma reached Pinatubo's surface on June 15, the volcano exploded in a cataclysmic eruption that ejected more than 5 km (1.2 cu mi) of material. The ash cloud from this climactic eruption rose 35 km (22 mi) into the atmosphere. At lower altitudes, the volcanic ash was blown in all directions by the intense cyclonic winds of a coincidentally occurring typhoon, and winds at higher altitudes blew the ash southwestward. A blanket of ash and larger pumice lapilli blanketed the countryside. Fine ash fell as far away as the Indian Ocean and satellites tracked the ash cloud several times around the globe.
Huge pyroclastic flows roared down the flanks of Mount Pinatubo, filling once-deep valleys with fresh volcanic deposits as much as 200 m (660 ft) thick. The eruption removed so much magma and rock from below the volcano that the summit collapsed to form a 2.5 km (1.6 mi) wide caldera.
Following the climactic eruption of June 15, 1991, activity at the volcano continued at a much lower level, with continuous ash eruptions lasting until August 1991 and episodic eruptions continuing for another month.
Later eruptions
Activity at the volcano remained low until July 1992 when a new lava dome started growing in the caldera. Volcanologists suspected that further violent eruptions could be possible, and some areas were evacuated. However, the eruption was only minor. The last eruption of Mount Pinatubo took place in 1993.
Lake Pinatubo
Main article: Lake PinatuboThe 1991 caldera afterwards filled with water from annual monsoon rains and a crater lake, Lake Pinatubo, was formed. In 1992, a growing lava dome formed an island, which was eventually submerged by the lake. Initially, the lake was hot and highly acidic, with a minimum pH of 2 and a temperature of about 40 °C (104 °F). Subsequent rainfall cooled and diluted the lake, lowering the temperature to 26 °C (79 °F) and raising the pH to 5.5 by 2003.
The lake deepened by about 1 meter (3.3 ft) per month on average, eventually submerging the lava dome, until September 2001, when fears that the walls of the crater might be unstable prompted the Philippine government to order a controlled draining of the lake. An estimated 9,000 people were once again evacuated from surrounding areas in case a large flood was accidentally triggered. Workers cut a 5-meter (16 ft) notch in the crater rim and drained about a quarter of the lake's volume.
Recent activity
On July 10, 2002, the west wall of the crater collapsed, slowly releasing approximately 160 million cubic meters (5.7×10^ cu ft) of water and sediment into the Maraunot River in Botolan, Zambales.
On July 26, 2011, a 5.9 magnitude earthquake struck close to Pinatubo; however, no major damages or casualties were reported.
On March 4, 2021, the PHIVOLCS raised alert level 1 over Mount Pinatubo after reporting an increase on its seismic activity. 1,722 volcanic earthquakes were also recorded within the vicinity of the volcano since January 2021.
On August 11, 2021, PHIVOLCS downgraded Mt. Pinatubo's Alert Level 1 to Level 0, due to "continued decrease in earthquake activity and a return to baseline seismic parameters".
PHIVOLCS said it noted a "significant decrease" in volcanic earthquakes, with a total of 104 quakes or an average 2–3 events per day recorded from July 1 – August 1, 2021.
On November 30, 2021, PHIVOLCS reported a weak explosion occurred on Mt. Pinatubo between 12:09 p.m. and 12:13 p.m., which produced a plume. The agency later confirmed it was a phreatic explosion produced by hydrothermal fluids near the surface, rather than a magmatic eruption.
Cultural history
The word pinatubo could mean "fertile place where one can make crops grow", or could mean "made to grow", in Sambal and Tagalog, which may suggest a knowledge of its previous eruption in about 1500 AD. There is a local oral tradition suggestive of a folk memory of earlier large eruptions. An ancient legend tells of Bacobaco, a terrible spirit of the sea, who could metamorphose into a huge turtle and throw fire from his mouth. In the legend, when being chased by the spirit hunters, Bacobaco flees to the mountain and digs a great hole in its summit showering the surrounding land with rock, mud, dust and fire for three days; howling so loudly that the earth shakes.
History among Aetas
Aeta elders tell many stories about the history of the mountain, the best known being that it was once a Batung Mabye (Kapampangan language for "living stone"). It was said to have been planted on a kingdom by a displeased sorcerer but relocated by a hero. The mountain was soon turned into the abode of Apo Namalyari ("The lord of happenings/events"), the pagan deity of the Sambal, Aetas and Kapampangans living on the Zambales range.
It was said to comprise the whole mountain range until Sinukuan of Mount Arayat (the god of the Kapampangans) became a strong rival of Namalyari. Their fight, which took place over the center plains, shattered the mountain into smaller bodies and Mount Arayat lost its center peak. Other versions have it that Pinatubo's peak shattered because of Namalyari's immense fury in an attempt to teach humans the meaning of fear and show how misdeeds will be punished.
According to the native elders, Apo Namalyari induced the June 1991 eruption because of displeasure toward illegal loggers and Philippine National Oil Company executives who performed deep exploratory drilling and well testing on the volcano looking for geothermal heat from 1988 to 1990. Discouraging results from the wells forced the abandonment of the prospect 13 months before the April 2, 1991, explosions.
Aetas granted ownership of Pinatubo
After being driven away by the 1991 eruption of Mount Pinatubo, in May 2009 some 454 Aeta families in Pampanga were given the first clean ancestral land ownership on Mount Pinatubo with the Certificate of Ancestral Domain Title (CADT) by the National Commission on Indigenous Peoples (NCIP), the government agency that deals with issues concerning indigenous people of the Philippines. The approved and declared net land area of 7,440.1 ha (18,385 acres) covers the barangays of Mawakat and Nabuklod in Floridablanca, Pampanga, plus a portion of San Marcelino, Zambales, and a portion of Barangay Batiawan in Subic, Zambales.
On January 14, 2010, some 7,000 Aeta families from Zambales were officially granted the Certificate of Ancestral Domain Title (CADT) covering the Zambales side of Pinatubo which includes the summit and Lake Pinatubo, officially becoming their lutan tua (ancestral land). The ancestral domain title covers 15,984 ha (39,500 acres) and includes the villages of Burgos, Villar, Moraza and Belbel in Botolan and portions of the towns of Cabangan, San Felipe and San Marcelino.
Ancestral domain titles are awarded to a certain community or indigenous group who have occupied or possessed the land continuously in accordance with their customs and traditions since time immemorial. They have the legal right to collectively possess and to enjoy the land and its natural resources to the exclusion of others. Having the land title will protect them from others – including foreigners – exploiting their land without compensation to and consent from the indigenous tribes. In the past, the Aetas had to contend with mining companies, loggers, and recently, tourist companies who earn from Mount Pinatubo but do not compensate the local tribes.
In popular culture
Long before Mount Pinatubo became famous for its cataclysmic eruption, Philippine president Ramon Magsaysay, a native of Zambales, named his C-47 presidential plane Mt. Pinatubo. The plane crashed into Mount Manunggal in Cebu province in 1957, killing the president and twenty-four others on board.
The shape of Mount Pinatubo's caldera inspired New Clark City Athletics Stadium in Capas, Tarlac.
Hiking activity
The caldera formed and Lake Pinatubo has, since June 15, 1991, become a tourist attraction with the preferred route through Barangay Santa Juliana in Capas, Tarlac.
Biodiversity
Mammals
The Long-nosed forest mouse (Apomys sacobianus) is a species of rodent endemic to Mount Pinatubo, Philippines.
The Zambales forest mouse (Apomys zambalensis) is a species of rodent endemic to Zambales Mountain Range, Philippines.
See also
- List of volcanoes in the Philippines
- List of volcanic eruptions by death toll
- Timeline of volcanism on Earth
Notes
- ^ "Pinatubo". Global Volcanism Program. Smithsonian Institution. Archived from the original on January 23, 2020. Retrieved January 23, 2020.
- "Pinatubo Volcano". The Philippine Institute of Volcanology and Seismology (PHIVOLCS). Archived from the original on January 29, 2009. Retrieved August 12, 2008.
- "Pinatubo: Eruptive History". Global Volcanism Program. Smithsonian Institution. Retrieved August 31, 2021.
- Sambal: Bakil nin Pinatobo; Kapampangan: Bunduk/Bulkan ning Pinatubu, Bunduk ning Apu Malyari; Pangasinan: Palandey/Bulkan na Pinatubu; Ilocano: Bantay Pinatubo; Tagalog: Bundok/Bulkang Pinatubo IPA: [pɪ.nɐˈtuː.boʔ]
- "Tarlac map". University of Texas in Austin Library. Archived from the original on July 31, 2019. Retrieved August 2, 2011.
- "Report of the Philippine Commission to the President, 1901 Vol. III" Archived November 30, 2016, at the Wayback Machine, pg. 141. Government Printing Office, Washington, 1901.
- ^ "The Cataclysmic 1991 Eruption of Mount Pinatubo, Philippines". Archived from the original on August 25, 2013. Retrieved April 9, 2007. This article incorporates text from this source, which is in the public domain.
- Rodolfo; Umbal; Alonso. "Two Years of Lahars on the Western Flank of Mount Pinatubo: Initiation, Flow Processes, Deposits, and Attendant Geomorphic and Hydraulic Changes". USGS Publications. Archived from the original on March 16, 2012. Retrieved March 7, 2012.
- Stephen Self; Jing-Xia Zhao; Rick E. Holasek; Ronnie C. Torres & Joey McTaggart (1999). "The Atmospheric Impact of the 1991 Mount Pinatubo Eruption". Archived from the original on August 2, 2014. Retrieved July 25, 2014.
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The atmospheric impact of the 1991 Mount Pinatubo eruption
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External links
Listen to this article (30 minutes) This audio file was created from a revision of this article dated 31 January 2006 (2006-01-31), and does not reflect subsequent edits.(Audio help · More spoken articles)- Fire and Mud: Eruptions and Lahars of Mount Pinatubo, Philippines, United States Geological Survey site
- "Weather effects of the 1991 eruption" EOS Volcanology.
- "The Cataclysmic 1991 Eruption of Mount Pinatubo, Philippines". United States Geological Survey site
- Pinatubo, Philippines (volcanic images)
- Entry for Pinatubo in the Smithsonian Institution's Global Volcanism Program (GVP)
Volcanoes of the Philippines | |||||||
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Active volcanoes |
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Potentially active volcanoes | |||||||
See also: List of mountains in the Philippines |
- Active volcanoes of the Philippines
- Calderas of Southeast Asia
- Landforms of Pampanga
- Landforms of Tarlac
- Landforms of Zambales
- Mountains of the Philippines
- Stratovolcanoes of the Philippines
- Subduction volcanoes
- VEI-6 volcanoes
- Volcanic crater lakes
- Volcanoes of Luzon
- Holocene stratovolcanoes
- Pleistocene stratovolcanoes
- Zambales Mountains