Moment magnitude scale

The moment magnitude scale (abbreviated as MMS; denoted as MW or M) is used by seismologists to measure the size of earthquakes in terms of the energy released. The magnitude is based on the seismic moment of the earthquake, which is equal to the rigidity of the Earth multiplied by the average amount of slip on the fault and the size of the area that slipped. The scale was developed in the 1970s to succeed the 1930s-era Richter magnitude scale (ML). Even though the formulae are different, the new scale retains a similar continuum of magnitude values to that defined by the older one. Starting in January 2002 the MMS is officially the scale used by the United States Geological Survey to calculate and report magnitudes for all modern large earthquakes.

Popular press reports of earthquake magnitude usually fail to distinguish between magnitude scales, and are often reported as "Richter magnitudes" when the reported magnitude is a Moment magnitude (or a surface-wave or body-wave magnitude). Because the scales are intended to report the same results within their applicable conditions, the confusion is minor.

Magnitude

Magnitude may refer to:

In mathematics:

  • Magnitude (mathematics), the relative size of an object
  • Norm (mathematics), a term for the size or length of a vector
  • Scalar (mathematics), a quantity defined only by its magnitude
  • Euclidean vector, a quantity defined by both its magnitude and its direction
  • Order of magnitude, the class of scale having a fixed value ratio to the preceding class
  • In astronomy:

  • Magnitude (astronomy), a measure of brightness and brightness differences used in astronomy
  • Apparent magnitude, the calibrated apparent brightness of a celestial object
  • Absolute magnitude, the brightness of a celestial object corrected to a standard luminosity distance
  • Instrumental magnitude, the uncalibrated apparent magnitude of a celestial object
  • Photographic magnitude, the brightness of a celestial object corrected for photographic sensitivity, symbol mpg
  • Magnitude of eclipse or geometric magnitude, the size of the eclipsed part of the Sun during a solar eclipse or the Moon during a lunar eclipse
  • Podcasts:

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    Latest News for: moment magnitude scale

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    Minor Earthquake Shakes Aigio, Greece

    Greek City Times 09 Jan 2025
    The Geodynamic Institute of Athens reported a preliminary magnitude of 3.7 on the Richter scale.
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    What is the ring of fire – explained in 30 seconds

    AOL 08 Jan 2025
    Many of the world’s most powerful earthquakes have occurred along this zone, including the 1960 Valdivia Earthquake, which had a magnitude of 9.5 on the moment magnitude scale, and the 1964 Alaska Earthquake, with a magnitude of 9.2 ... .
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    Ohio had 2 noticeable earthquakes in less than 2 weeks. When did one last hit Cincinnati?

    Cincinnati.com 29 Dec 2024
    Geological Survey.Early Sunday, the USGS recorded a 2.9-magnitude earthquake in northwest Ohio ... Both quakes exceeded 2.5 on the moment magnitude scale, which measures the strength of an earthquake ... All but four ranked lower than 2.5 in magnitude.
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    Living through history in the making

    Israel Hayom 25 Dec 2024
    ... many describe as biblical in scale. While we sense its magnitude, recent months have shown how unpredictable such moments can be, even in the shortest timeframe – a mere blink in historical terms.
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    'Swaying back and forth': Magnitude 7 earthquake, aftershocks rock California

    Visalia Times Delta 06 Dec 2024
    A magnitude 7 earthquake struck along the San Andreas fault, triggered a now-discontinued tsunami warning from Oregon to San Francisco ... Magnitude is a measurement of the strength of an earthquake. Officially it's called the moment magnitude scale.
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    Magnitude 7.0 earthquake rocks California, generates tsunami warning

    Azcentral 05 Dec 2024
    SAN FRANCISCO ‒ A magnitude 7.0 earthquake struck near the town of Petrolia in California Thursday at 10.44 a.m ... Magnitude is a measurement of the strength of an earthquake. Officially it's called the moment magnitude scale.
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    Magnitude 7 earthquake rocks California, tsunami warning stretches to San Francisco Bay

    The Register Guard 05 Dec 2024
    SAN FRANCISCO ‒ A magnitude 7.0 earthquake struck near the town of Petrolia in California Thursday at 10.44 a.m ... Magnitude is a measurement of the strength of an earthquake. Officially it's called the moment magnitude scale.
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    Live updates: Tsunami warning issued for Oregon after earthquake off California coast

    Statesman Journal 05 Dec 2024
    Magnitude is a measurement of the strength of an earthquake. Officially it's called the moment magnitude scale. It's a logarithmic scale, meaning each number is 10 times as strong as the one before it.
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    Magnitude 7 earthquake rocks California. Has tsunami threat passed?

    Cincinnati.com 05 Dec 2024
    SAN FRANCISCO ‒ A magnitude 7.0 earthquake struck near the town of Petrolia in California on Thursday at 10.44 a.m ... Magnitude is a measurement of the strength of an earthquake. Officially it's called the moment magnitude scale.
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    Magnitude 7 earthquake rocks California; tsunami warning stretches part of Oregon Coast

    Statesman Journal 05 Dec 2024
    SAN FRANCISCO ‒ A magnitude 7.0 earthquake struck near the town of Petrolia in California Thursday at 10.44 a.m., generating a tsunami warning stretching from southern Oregon to San Francisco ... Officially it's called the moment magnitude scale.
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    Live updates: Tsunami warning canceled for Oregon after earthquake off California coast

    The Register Guard 05 Dec 2024
    Magnitude is a measurement of the strength of an earthquake. Officially it's called the moment magnitude scale. It's a logarithmic scale, meaning each number is 10 times as strong as the one before it.
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    Earthquake Preparedness in the Mediterranean

    LGC News 30 Nov 2024
    Following a magnitude 5.2 earthquake in the Mediterranean, former ... Aysal referred to the earthquake, which registered as 4.8 on the moment magnitude scale and was felt between Antalya and Cyprus.
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    Sustainability is one thing and more

    Manila Bulletin 26 Nov 2024
    A balanced energy mix has the advantage of flexibility and adaptability, such that when new technologies are ripe for scaling, our energy system can adapt at the opportune moment. Given the magnitude ...
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    The Science Behind The Nepal Earthquake

    IFL Science 14 Nov 2024
    The April 25 quake measured 7.8 on the moment magnitude scale, the largest since the 1934 Bihar quake, which measured 8.2 and killed around 10,000 people.
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    Colombia Declares Natural Disaster Due To Heavy Rain

    Colombia One 11 Nov 2024
    Credit. Presidency of Colombia ... There are impacts in various departments at this moment of varying magnitude, but there are three areas today with a much larger scale, and that is where part of the effort will be focused ... Alta Guajira, Choco and Bogota.

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