Source Characteristics of Earthquakes Occurring in the Vicinity of Kyoto

Abstract

Low magnification seismograms recorded at Abuyama Seismological Observatory are Fourier analyzed for estimating and comparing the source parameters of earthquakes of magnitude of 4.5 or greater occurring in the vicinity of Kyoto. A comparison of spectral parameters by use of an Ω-f_c diagram illustrates a fairly striking contrast of source parameters between the northern and southern sources. Earthquakes with high aftershock activity are, in general, characterized by low stress drop compared with earthquakes with low aftershock activity. The northern sources have generally higher stress drops and smaller dimensions than the southern sources and Wachi earthquakes. A possible interpretation of the high stress drop in the northern part may be that higher effective stress is acting there. The regional variation of seismic wave attenuation reported in a previous paper seems to support this interpretation.