Geography & Earth
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Moment Magnitude

Modern magnitude from the seismic moment of a quake.

Formula

Mw=23log⁡10M0−10.7M_w = \tfrac{2}{3}\log_{10} M_0 - 10.7

Variables

M_0Seismic moment (N·m)
M_wMoment magnitude

Example

A moment of 10²² N·m gives Mw ≈ 8.0

Did You Know?

It replaced the Richter scale for big quakes because Richter "saturates" and can't tell a magnitude 8 from a 9.

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