表面波マグニチュード───Ms surface
実体波マグニチュード───mB body

Surface wave magnitude
Body wave magnitude
Moment magnitude scale

地震のマグニチュード (magnitude) とは、地震が発するエネルギーの大きさを対数で表した指標値である。揺れの大きさを表す震度とは異なる。日本の地震学者和達清夫の最大震度と震央までの距離を書き込んだ地図[1]に着想を得て、アメリカの地震学者チャールズ・リヒターが考案した[2][3]。リヒター[4]の名からリヒター・スケール(Richter scale、英語発音: [riktər skeil](リクター・スケール))ともいい[5]、英語圏では「マグニチュード」よりも「リヒター・スケール」の名称が一般的である。マグニチュードは地震のエネルギーを1000の平方根を底とした対数で表した数値で、マグニチュードが 1 増えると地震のエネルギーは約31.6倍になり、マグニチュードが 2 増えると地震のエネルギーは1000倍になる。
地震学ではモーメントマグニチュード (Mw) が広く使われる。日本では気象庁マグニチュード (Mj) が広く使われるが、長周期の波が観測できるような規模の地震(Mj5.0以上)[6]ではモーメントマグニチュードも解析・公表されている。
引用元:マグニチュード – Wikipedia https://ja.wikipedia.org/wiki/%E3%83%9E%E3%82%B0%E3%83%8B%E3%83%81%E3%83%A5%E3%83%BC%E3%83%89

The Richter magnitude scale (also Richter scale) assigns a magnitude number to quantify the energy released by an earthquake. The Richter scale, developed in the 1930s, is a base-10 logarithmic scale, which defines magnitude as the logarithm of the ratio of the amplitude of the seismic waves to an arbitrary, minor amplitude.

As measured with a seismometer, an earthquake that registers 5.0 on the Richter scale has a shaking amplitude 10 times that of an earthquake that registered 4.0, and thus corresponds to a release of energy 31.6 times that released by the lesser earthquake.[1] The Richter scale was succeeded in the 1970s by the moment magnitude scale. The moment magnitude scale is now the scale used by the United States Geological Survey to estimate magnitudes for all modern large earthquakes.[2]
引用元:Richter magnitude scale – Wikipedia, the free encyclopedia https://en.wikipedia.org/wiki/Richter_magnitude_scale

The surface wave magnitude ( {\displaystyle M_{s}} M_{s}) scale is one of the magnitude scales used in seismology to describe the size of an earthquake. It is based on measurements in Rayleigh surface waves that travel primarily along the uppermost layers of the Earth. It is currently used in People’s Republic of China as a national standard (GB 17740-1999) for categorising earthquakes.[1]
引用元:Surface wave magnitude – Wikipedia, the free encyclopedia https://en.wikipedia.org/wiki/Surface_wave_magnitude

Body wave magnitude ( {\displaystyle m_{b}} m_b) is a way of determining the size of an earthquake, using the amplitude of the initial P-wave to calculate the magnitude. The P-wave is a type of body wave that is capable of traveling through the earth at a velocity of around 5 to 8 km/s, and is the first wave from an earthquake to reach a seismometer. Because of this, calculating the body wave magnitude can be the quickest method of determining the size of an earthquake that is of a large distance from the seismometer.
引用元:Body wave magnitude – Wikipedia, the free encyclopedia https://en.wikipedia.org/wiki/Body_wave_magnitude

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.[1] 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.[2] 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.[3]
引用元:Moment magnitude scale – Wikipedia, the free encyclopedia https://en.wikipedia.org/wiki/Moment_magnitude_scale