Body wave magnitude

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Body wave magnitude (m_b) is one of many ways of determining the size of an earthquake. It is calculated by measuring the amplitude, or size, of the initial P-wave. Since the P-wave is the first wave from an earthquake to arrive at a seismograph station, calculating the body wave magnitude is the quickest way to determine the magnitude of a distant earthquake.

Limitations in the calculation method mean that the body wave magnitude saturates at around 6 - 6.5m_b, with the figure staying the same even when the moment magnitude may be higher.

[edit] See also

• Seismic scale
• Moment magnitude scale