1986年ニアムラギラ火山の側噴火

キタツングルワ (Kitazungurwa)

抄録

An eruption occurred on the southern flank of Nyamuragira at 15 hours local time on July 16, 1986, after two years and four months' dormancy. A swarm of earthquakes preceded the eruption by thirteen hours. Much lava poured out from a small lava pond during the first two days of eruption. The eruptive activity became lava fountain type and much scoria and lava were ejected. New scoria cones were formed at craters and were growing up to a cone with diameter of 700m and height of 80m until the end of eruption. The new cone was called Kitazungurwa (meant the irreplaceable place) by the local people. Eruptive activity changed to Strombolian eruption on three days before the end of eruption. Simultaneously, seismic activity changed from continuous tremors to isolated ones. A lot of small or micro-earth-quakes were observed when the eruptive activity ceased. The sources of tremors were located just beneath the craters and hypocenters of earthquakes were at south of them. Lava flowed about 19km toward south with mean width of 1km and mean thickness of 2m. Total volume of scoria and lava erupted is estimated to be 50×10⁶m³.