Relation between Seismic Moment M0 and Surface Wave Magnitude Ms.

The relation between ms and logm0 is examined using harvard cmt m0, with both mprague s and the improved surface wave magnitude scale mt s [1] applied to isc data. although mt s shows less scatter than mprague s , neither dataset supports a slope of ms against logm0 which tends to 1.0 towards smaller magnitudes. instead, a good linear fit of slope 0.76 using ts m is found throughout the fitted range of m0 (2.0×10^24 to 1.26×10^27 dyne-cm), and this linearity extends down tom0=2.5×10^23 dyne-cm. this suggests that previous proposals that ms data support a theoretical slope of 1.0 in the low range of magnitude which may be expected from established relationships, is not justified.