48. The 1959 Eruption of Simmoe-dake and the 1961 Iimori-yama Earthquake Swarm

Kirisima Volcano which is situated 50km north of Sakura-zima Volcano has been studied from geophysical points of view, namely, seismic and geothermal observations which commenced after the phreatic eruption of Simmoe-dake in 1959. Kirisima Volcano consists of many cones the arrangement of which is roughly north-west and south-east. Seismic events during the period 1959-1966 are described based on observational facts. In March, 1964, Kirisima Volcano Observatory was established at Ebino. Since then, further extensive seismic, geothermal and geomagnetic surveys were conducted at Kirisima Volcano. Earthquakes wrhich are originated from Kirisima Volcano have the focal depths of between 1km and 10km and no shallow earthquakes have been observed excepting at the time of the 1959 Simmoe-dake eruption. Measurements of underground temperature at Ebino clarified the gradual shift of high temperature region towards the west.|1959年2月,霧島火山の新燃岳が長い静穏期に終りを告げて水蒸気爆発を行なつた.噴出物の調査によれば爆発の運動のエネルギーは1019エルグと推定された.爆発直後実施した地震観測によれば,火山性地震が新燃岳のごく浅い場所に発生していることが判つた.また新燃岳に最も近い地震計は最大1.5ミクロンに達する火山性脈動を記録した