SEISMICITY IN ANTARCTICA
1976 Volume 24 Issue 4 Pages 381-395
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1976 Volume 24 Issue 4 Pages 381-395
The Antarctic Continent and the surrounding ocean, which is called the Antarctic plate, enclosed by marginal seismic belts is one of the large aseismic areas on the earth, though there are active volcanoes in West Antarctica and the Ross-Weddell Graben. More than ten seismological stations have been established in Antarctica since International Geophysical Year (IGY) of 1957. However no earthquakes have been located in the Antarctic area by the World Wide Seismological Station Network (WWSSN), with the exception of volcanic eruptions of Deception Island.
"The Antarctic Seismological Bulletin" has been published on the basis of phase readings from the Antarctic Seismological Stations. The events for which the phase readings of P wave arrival time were reported from more than four stations, but for which the hypocenter determination was not made, were found in the bulletin.
Seismograms at Japanese Antarctic Station, Syowa, in Lutzow-Holm Bay, East Antarctica, seem to indicate the occurrence of some micro-earthquakes. This fact suggests the possibility of the occurrence of small/micro-earthquakes in other part of the Antarctica.
The present paper attempts to confirm the existence of earthquakes in Antarctica on the basis of the data from WWSSN and of temporary seismological observations at some stations in Antarctica.
The main results are summarized as follows:
1) Small earthquakes occur at least in West Antarctica and in the Ross-Weddell Graben, though the activity is very low. But the earthquakes are not generally detectable by the insufficient seismological network in Antarctica.
2) The seismicity around Syowa Station in East Antarctica is less than one micro-earthquake per month. However earthquakes occur in the marginal zone of East Antarctic Shield area.
3) The seismicity around the Dry Valleys in Victoria Land is one micro-or ultra micro-earthquake every two days and that around McMurdo Station on Ross Island is one earthquake per day.
4) The seismic activity in the volcanic region in the Antarctic is relatively higher than that in the surrounding region.
5) The seismicity in West Antarctica and in the Ross-Weddell Graben is some ten times higher than that in East Antarctica.
