Search

The article considers the characteristics of the short-period S-wave attenuation field in the lithosphere of Southwestern Japan. Records of local shallow earthquakes, obtained by station MAJO at distances of ~250–900 km, were processed. We used a method that analyzes the ratio of the maximum amplitudes of Sn- and Pn-waves (Sn/Pn parameter). The dependence of this parameter on distance was plotted. We compared this dependence with analogous dependences, obtained earlier in Northeastern Japan and in the rupture zone of the great Maule earthquake (Central Chile, February 27, 2010, Mw = 8.8). The reasons for the substantial differences of these dependences in different regions are discussed. The study considers the correlation of the Sn/Pn parameter values, recorded near the rupture zones of large earthquakes in Southwestern Japan (Mw ≥ 7.0) with the passage of time after the corresponding events. Particular attention is paid to the apportionment of high attenuation zones in areas where large earthquakes that have occurred since 1900 are not known. By analogy with earlier data, it is suggested that preparation for a large seismic event can occur in such a zone. [ABSTRACT FROM AUTHOR]