The Japan Meteorological Agency magnitude scale () is a seismic magnitude scale set by the Japan Meteorological Agency.
Overview In Japan, for shallow (depth < 60 km) earthquakes within 600 km, the Japan Meteorological Agency (JMA) calculates; , p. 78; . a magnitude labeled MJMA, MJMA, or MJ. (These should not be confused with moment magnitudes JMA calculates, which are labeled Mw(JMA) or M(JMA), nor with the Shindo intensity scale.) JMA magnitudes are based (as typical with local scales) on the maximum amplitude of the ground motion; they agree "rather well". with the seismic moment magnitude in the range of 4.5 to 7.5,See also figure 3.70 in NMSOP-2. but underestimate larger magnitudes.
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