Earthquake swarms observed at Mount Erebus, Antarctica in 1985-1986

• Main Author: Katsumi Murayama
• Format: Article in Journal/Newspaper
• Language: English; Japanese
• Published: National Institute of Polar Research 1989
• Subjects: Geography (General); G1-922; New Zealand; Mount Erebus; Hoopers Shoulder; Antarc*; Antarctica
• Online Access: https://doi.org/10.15094/00008628; https://doaj.org/article/ce844a43f29f4a9ea95aed977e7a6634

Mount Erebus (77°32′S, 167°09′E, 3794m) is one of the active volcanos in Antarctica. A program to monitor the seismic activity of Mount Erebus was started in December 1980 as an international cooperative program of Japan, the United States and New Zealand, named IMESS (International Mount Erebus Seismic Study). Usually 10-30 volcanic earthquakes were recorded per day for the period from 1985 to 1986. Three earthquake swarms (85-A, 86-A, 86-B) with more than 250 events occurring within 24 hours were recorded in 1985 and 1986. The activities of swarms 85-A, 86-A and 86-B are as follows : 1) The duration of the activities was 66,24 and 59 hours. 2) The total number of the earthquakes was 2315,357 and 689 events. 3) The average number of the earthquakes per hour was 35.1,14.9 and 11.7. 4) Ishimoto-Iida's "m"-value of the three earthquake swarms was 2.14±0.10,2.54±0.32 and 2.62±0.23,respectively. 5) The hypocenters of swarm 86-A were located at the western part in Mount Erebus. 6) Hypocenters of swarms 85-A and 86-B were difficult to determine because the number of operating stations was not large enough for undertaking hypocenter determination. The hypocenters of the swarms 85-A and 86-B were estimated to be located in the same area as that of 86-A, on the basis of using the arrival times of initial phases and the amplitudes of the seismic waves at Hoopers Shoulder and Trancated Cone Stations.