Figure 2.15 shows the approximate relationships between several different earthquake
magnitude scales. When we view the data shown in Fig. 2.15, it would appear that there is
an exact relationship between the moment magnitude Mw and the other various magnitude
BASIC EARTHQUAKE PRINCIPLES 2.19
FIGURE 2.15 Approximate relationships between the moment magnitude scale Mw and other magnitude
scales. Shown are the short-period body wave magnitude scale mb, the local magnitude scale ML, the longperiod
body wave magnitude scale mB, the Japan Meteorological Agency magnitude scale MJMA and the surface-
wave magnitude scale MS . (Developed by Heaton et al. 1982, reproduced from Idriss 1985.)
BASIC EARTHQUAKE PRINCIPLES
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