SEISMIC ACTIVITY OF MOUNT EREBUS, ANTARCTICA IN 1989

概要

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Seismic observations of Mount Erebus (77°37′S, 167°09′E, 3794m) on Ross Island, Antarctica have been operated by international cooperative programs since December 1980. The annual mean number of earthquakes per day counted at the summit station E1 of Mount Erebus was 47 in 1989. This value indicates that the low seismic activity after the 1984 volcanic event still continued until 1989. However, the seismic activity in 1989 can be divided into two phases in the periods of January-August and September-December. The average daily count of earthquakes for the former phase was 61 and that for the latter one was 15. The seismic activity in the former phase was higher than that in the latter one. The hypocenters of only 12 earthquakes were determined in 1989 by using the P arrival time readings at five stations. The distribution of the earthquakes in 1989 is similar to those in the previous years after the 1984 volcanic event. The average daily number of earthquakes in 1988 was 15 and the surface of the lava lake of Mount Erebus solidified in December 1988. On the other hand, the average daily number of earthquakes in 1989 was 47 and the surface of the lava lake was melted again in December 1989. It seems that the seismic activity of Mount Erebus in 1989 was slightly higher than that in 1988.
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