Historical Seismograms - Evidence from the AD 2000 Izu Islands ...

3 10 N. N. Ambraseysa00 .Msc760 ...=..Y=*50I 1 I I5 6 7 Ms 8Figure 2. Plot of magnitude Msc predicted from Equation (2) using fault parametersin Bonilla, et al. (1984) circles, and Nowroozi (1985) squares, versus corresponding surfacewave magnitude Ms reported by these authors. This figure includes events No. 1 and10 in Nowroozi's Table 1, the latter with the correct Ms-value of 7.4. The same figureexcludes event 46 of the Calingiri earthquake, for which R = O.lm and Ms = 5.2. TheIranian data give Msc = 0.53 + 0.94 Ms and the world data give Msc = 0.93 + 0.87 Ms.Equations (1) and (2) may be used to estimate the magnitude of historical eventsin the Alpine region from faults of known or inferred length and mobility. Of thesetwo equations, the highest correlation coefficient is obtained for Equation (2) or forequations of the type Msc - log(L"R").REFERENCESAmbraseys, N. (1976). Earthquake epicentres in Iran, Cento Seminar Proc. on RecentAduanc. Earthq. Hazard Minimization, 70-80, Tehran.Ambraseys, N. and C. Melville (1982). A History of Persian Earthquakes, Cambridge Univ.Press.Bonilla M., R. Mark, and J. Lienkaemper (1984). Statistical relations among earthquakemagnitude, surface rupture length and surface fault displacement, Bull. Seism. SOC.Am., 74, 2379-2411.Nowroozi, A. (1985). Empirical relations between magnitudes and fault parameters forearthquakes in Iran, Bull. Seism. SOC. Am., 75, 1327-1338.