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• For the "small letter m with dot below" please use the HTML encoding "&7747;".

Given a valid code (see table), outputs an earthquake magnitude scale label, either the generic M, or a subtype (such as M_w  or mb_Lg ) with a subscript conformable with the symbols most commonly used by the major seismological authorities;. The article is automatically added to a tracking category. Optionally adds a value or relation, identifies a source, or links to explanatory text (at Seismic scale).

Usage

• {{ M | <code> | <value or relation> | src = <source> | link=y }}

A valid "code" is required (see table), other parameters are optional.

Examples

Label only:

• {{M|w}} → M_w 

Label with wikilink to explanatory text (useful for first mention):

• {{M|w|link=y}} → M_w
• {{M|t|link=y}} → M_t

With a value or range:

• {{M|w|6.1}} → M_w 6.1.
• {{M|w|6.2 – 6.5}} → M_w 6.2 – 6.5

To show that a magnitude is from a particular catalog or source:

• {{M|w|8.1|src=HRV}}, {{M|e|8.8|src=NEIC}} → M_w  8.1,   M_e  8.8

There are multiple magnitude scales. To maintain accuracy and avoid error please use the proper code. If you are uncertain use the special maintenance code "?":

• {{M|?}} → M

 Important note: Please do NOT specify a magnitude as "Richter scale" just because a newspaper or other popular media says "Richter". That is usually incorrect. Earthquake magnitudes reported by the U.S. Geological Survey (USGS) and other seismological authorities now generally use the moment magnitude scale. While most newspapers and other popular media refer to this as the "Richter" scale, this is not correct. The Richter magnitude scale, explicitly denoted with the symbol "ML" or "M_L" (where "L" indicates "local"), was developed for measuring the magnitude of earthquakes in the vicinity of southern California. While the "Richter" and moment magnitude scales are similar, they do differ, particularly for larger earthquakes.

In general: where any source specifies magnitude on a scale other than "Richter", or uses "M" (or "m") with one or more other letters (such as ML, Mw, Ms, or mb), that can be relied on; use the table below to match the symbol and determine the proper code. E.g.: {{M|w|9.0}}.

Where a newspaper or other popular refers to the "Richter" scale or magnitude of a recent earthquake it is probably the popular mis-identification of the moment magnitude scale. Best practice is to check with an authoritative source, such as the USGS (here or here). USGS policy is that magnitudes in press releases, indicated as "M", are implicitly moment magnitude. For such cases use the "dot" code: {{M|.|~6.8}}. This displays as "M~6.8". If an authoritative source is not available use {{M|R?}} to indicate a dubious use of "Richter".

Note that the magnitudes issued immediately following a large earthquake are preliminary. These are generally revised days, months, or even years later, as more information is obtained. The authoritative magnitude of a quake "for the record", or for comparing with other earthquakes, should always be taken from an authoritative earthquake catalog, such as the International Seismological Centre catalog.

It is recommended that the first use or mention of a magnitude scale in the article text be wikilinked with the |link=y parameter.

Table

These are the most commonly found scales of earthquake magnitude. Any scale not found in this table is mostly likely one of the following:

• An intensity scale. See Seismic scale for explanation. This template does not cover intensity scales.
• A regional (or "local") scale used by some particular seismic network (or country). In general it is preferable to use one of the better known scales from the table. Exceptions are for historical reports; you will need to explicitly format as appropriate. If the scale has been properly calibrated (see MNSOP-2, Chapter 3, §3.2.4.3, p. 65) then "L" may be appropriate, along with the |src= parameter.
• A technical scale. While these might come up in an article related to seismology, they are not appropriate for general description of earthquakes. If needed, please format appropriately. On first use be sure to add a footnote explaining the scale.

** Forms used by various agencies is incomplete. **

Examples of use are from the International Association of Earth Physics and Interior (IASPEI), the first edition of the New Manual of Seismological Practice (NMSOP)(the second edition follows the IASPEI), the United States Geological Survey (USGS) National Earthquake Information Center (NEIC), the International Seismological Centre (ISC), and the Bulletin of the Seismological Society of America (BSSA), as summarized in table 3 of the IASPEI/MNSOP-2 Information Sheet 3.3.

The nomenclature style implemented here is adapted from IASPEI/MNSOP-2 Information Sheet 3.3. This style differs from IASPEI style mainly in using subscripts but not underscores, and from BSSA style mainly in not using parentheses.

Additional magnitude scales from Chapter 3 of MNSOP-2, ISC documentation, the USGS, and a review of the literature. Section numbers are for either Chapter 3, or the Information Sheet.

"Cat.": the Categories for tracking use of these various scales. "#" is the number of pages in that category (when last checked).

Principal references:

• Bormann, P., ed. (2012), New Manual of Seismological Observatory Practice 2 (NMSOP-2), Potsdam: IASPEI/GFZ German Research Centre for Geosciences, doi:10.2312/GFZ.NMSOP-2.

• Bormann, P.; Dewey, J. W. (2014), "Information Sheet 3.3: The new IASPEI standards for determining magnitudes from digital data and their relation to classical magnitudes." (PDF), in Bormann (ed.), New Manual of Seismological Observatory Practice 2 (NMSOP-2), doi:10.2312/GFZ.NMSOP-2_IS_3.3.