Organization:Japan Meteorological Agency magnitude scale

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The Japan Meteorological Agency magnitude scale (Japanese: 気象庁マグニチュード) is a seismic magnitude scale set by the Japan Meteorological Agency.[1]

Overview

In Japan, for shallow (depth < 60 km) earthquakes within 600 km, the Japanese Meteorological Agency calculates[2] 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"[3] with the seismic moment magnitude Mw  in the range of 4.5 to 7.5,[4] but underestimate larger magnitudes.

Notes

  1. 第2版,世界大百科事典内言及, 日本大百科全書(ニッポニカ),精選版 日本国語大辞典,ブリタニカ国際大百科事典 小項目事典,知恵蔵,デジタル大辞泉,百科事典マイペディア,世界大百科事典. "マグニチュードとは" (in ja). https://kotobank.jp/word/%E3%83%9E%E3%82%B0%E3%83%8B%E3%83%81%E3%83%A5%E3%83%BC%E3%83%89-135837. 
  2. Katsumata 1996; Bormann, Wendt & Di Giacomo 2013, §3.2.4.7, p. 78; Doi 2010.
  3. Bormann & Saul 2009, p. 2478.
  4. See also figure 3.70 in NMSOP-2.

Sources