浅間山における人工地震探査--探査の概要と初動の走時について

概要

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In order to investigate the subsurface seismic structure beneath Asama Volcano, Japan, an active seismic experiment was conducted in October, 2006 with 60 participants from nine national universities and Japan Meteorological Agency as the 12 th joint experiment under the National Project for Prediction of Volcanic Eruptions. The experiment was conducted by recording seismic waves exerted from five dynamite shots with charges of 250.300kg. The seismic waves were recorded by 464 seismometers with a natural frequency of 2Hz and 210 seismometers with a natural frequency of 4.5Hz and data loggers temporally deployed around Asama Volcano. To reveal the P-wave velocity structure, 1839 useful arrival times were picked from the seismograms. Observed data suggests that the subsurface structure is likely to be highly heterogeneous and seems to be consistent with previous geophysical and geological studies