Relation between Seismic Moment M0 and Surface Wave Magnitude Ms

The relation between MS and logM0 is examined using Harvard CMT M0, with both and the improved surface wave magnitude scale [1] applied to ISC data. Although shows less scatter than , 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 is found throughout the fitted range of M0 (2.0×1024 to 1.26×1027 dyne-cm), and this linearity extends down to M0=2.5×1023 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.