The characteristics of J-Array seismograms

Abstract

The J-Array is a large-aperture seismic array system in Japan, which consists of 14 regional seismic networks deployed for research on earthquake prediction. During the project period (1991-1992), many seismograms from 61 teleseismic events (M≥5.8) were collected for studies on structures deep inside the Earth. A report summarizing J-Array seismograms was published in 1994 in order to show the characteristics of seismograms and evaluate the quality of their waveforms. In this paper, the characteristics of J-Array seismograms are introduced and discussed briefly. The seismograms from a large, dense distribution of seismic stations have a high potential to detect weak onsets of unknown phases, which may reveal hidden structures in the Earth's interior. Using the J-Array seismograms, two distinct unknown phases are presented and their tentative interpretations are proposed.