The 20-second regional magnitude M ^sub S^(20R) for the Russian Far East

• Published in: Seismic instruments 2011-09, Vol.47 (3), p.241
• Main Authors: Chubarova, O S, Gusev, A A, Vikulina, S A
• Format: Article
• Language: English
• Subjects: Earthquakes; Geophysics; Island arcs; Seismic activity; Seismic waves; Seismology; Surface waves
• ISSN: 0747-9239; 1934-7871
• DOI: 10.3103/S0747923911030042

A new modified magnitude scale M ^sub S^(20R) is elaborated. It permits us to extend the teleseismic magnitude scale M ^sub S^(20) to the regional epicenter distances. The data set used in this study contains digital records at 12 seismic stations of 392 earthquakes that occured in the northwest Pacific Ocean in the period of 1993-2008. The new scale is based on amplitudes of surface waves of a narrow range of the periods (16-25 s) close to the period of 20 s, for distances of 80-3000 km. The digital Butterworth filter is used for processing. On the basis of the found regional features concerning distance dependence for seismic wave attenuation, all the stations of the region have been subdivided into two groups, namely, "continental" and "island-arc." For each group of stations, its own calibration function is proposed. Individual station corrections are used to compensate for the local features. The magnitude scale M ^sub S^(20R) makes it possible to obtain a spectral-determined magnitude estimation at the regional distances and allows us to provide historical continuity with Gutenberg's M ^sub S^, classical scale. The single-station rms accuracy of determination of M ^sub S^(20R) is 0.22.[PUBLICATION ABSTRACT]