桜島火山の火山性微小地震と爆発の研究(2) ―火山性地震の震源分布―

Abstract

In order to make clear the location of hypocenter of volcanic earthquakes originating in the Sa-kurajima volcano, temporal seismemetric observation was performed. Eleven observation pointswere distributed around the crater. Analyzing sha data of March and April, 1970, the followingresults are obtained.1) The large majority of hypocenter of A type volcanic earthquakes are deep. The large psrtof hypocenters of the volcanic earthquakes which are not recognized clear P and S wave phase, areshallow, but there are some one which are deep.2) The seismicity at the crater rim is heighter than that within the crater.3) There is possibillity to know the new volcanic active place from the hypocenter distribution ofthe shallow earthquakes in the volcanic region.4) Hypocenter distribution which suggeste the existance of magma resovoir, is obtained.