1974年伊豆半島沖地震の余震観測報告 : 御前崎観測点

概要

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1974年伊豆半島沖地震調査概報An earthquake occurred at the tip of Izu Peninsula having M=6.9, at 08:33 on May 9th, 1974. Many buildings were destroyed, and twenty-nine persons were killed. Aftershock observation was carried out at Omaezaki in Shizuoka Prefecture. Many aftershocks and a small number of local earthquakes (S-P=about 5 seconds) were observed. The hypocenters for the latter could not be determined because no other station detected their shocks. Large travel time anomaly existed. The arrival time was usually 1.5 seconds later than the arrival expected. This anomaly may have been due to thick sediments. under the station, or the velocity model used in the present study.