大隅半島東方沖の一部領域で短時間に地震が連発する原因の考察

抄録

In a small area off the eastern coast of Osumi Peninsula, eight events have been observed from January 2001 to March 2019, in which M3 to M4 earthquakes occurred successively in a short time, from several seconds to several minutes. Based on the waveform correlation and cluster analysis, we found three seismic patches (asperities) which generate small repeating earthquakes in this area. The arrival time differences between P and S waves of the three patches’ earthquakes observed at NARU station suggested that these patches were close to each other. Furthermore, we confirmed that many earthquakes originated from these patches were included in the successive occurrences of earthquakes in this area. These results suggest that the earthquake from one of these patches affects another patch in the immediate vicinity and triggers successive occurrences of earthquakes.