1990年代の太平洋西縁域における地震活動の異常な活発化 Anomalous Seismic Activity in the Western Peripheral Region of the Pacific Ocean in 1990s
Seismic activity in and around the Japanese islands was conspicuously high in the mid1990s. Further, a number of large earthquakes occurred around the Philippine islands in the early 1990s, and then, around Kalimantan, Sulawesi, Java, and western New Guinea islands. We show that the seisimic activity in the western peripheral region of the Pacific Ocean in 1990s was so remarkable that it contributed substantially to the notable increase of seismic energy released in 1995-1996 worldwide. The activity seems to have started in the region near the Philippine islands. It is improbable, however, that the successive occurrence of large earthquakes in the western peripheral region of the Pacific Ocean was triggered by the impact of one particularly big event such as the 1990 Philippine earthquake or the huge 1991 eruption of Mt. Pinatubo. Instead, we think that the activity might be produced by a slow tectonic event that lasted for a few years and had a spatial scale of several thousands of kilometers.
地學雜誌 111(3), 395-403, 2002