Estimation of crustal structure in Horonobe area, Hokkaido, Japan, by using Multiplet-Clustering analysis

マルチプレットクラスタリング解析による幌延地域の地殻構造推定

森谷 祐一*; 浅森 浩一; 北村 至*; 堀田 光*; 大原 英史*; 新里 忠史  

Moriya, Hirokazu*; Asamori, Koichi; Kitamura, Itaru*; Hotta, Hikaru*; Ohara, Hidefumi*; Niizato, Tadafumi

本研究では、マルチプレットクラスタリング法を用いて、幌延地域において発生した浅発地震の震源を再決定した。その結果、本地域下で発生した221個の微小地震の震源は、深さ10-20km及び25-30kmにおいて南北方向に連続した領域に集中して分布することが明らかになった。

Hypocenter locations of shallow earthquakes in Horonobe area were determined to reveal the mechanisms of earthquake occurrence. The absolute source locations of 211 earthquakes were determined; then, those earthquakes with similar waveforms were identified, and the source locations of 26 multiplet groups were relocated by using cross-spectrum and clustering analyses. The relocated hypocenters allowed two seismically active areas to be identified, at 10-20 km and around 25-30 km depth. The earthquake locations indicate structures trending nearly N-S, and the structures causing repeated stick-slips at asperities, thus generating similar earthquakes.