Focal mechanisms and seismic moments of large earthquakes in the Antarctic Peninsula-Drake Pasage region (abstract)

• Main Authors: Ichiro Kawasaki, Yasutoshi Kawahara, Kazuo Shibuya, Katsutada Kaminuma
• Format: Report
• Language: English
• Published: Department of Earth Sciences, Toyama University/Department of Earth Sciences, Toyama University/National Institute of Polar Research/National Institute of Polar Research 1983
• Subjects: Antarctic; The Antarctic; Antarctic Peninsula; Drake Passage; South Shetland Islands; Pacific; Indian; North Scotia Ridge; Adie; Antarc*; Memoirs of National Institute of Polar Research; Polar Research
• Online Access: https://nipr.repo.nii.ac.jp/?action=repository_uri&item_id=1466; http://id.nii.ac.jp/1291/00001466/; https://nipr.repo.nii.ac.jp/?action=repository_action_common_download&item_id=1466&item_no=1&attribute_id=18&file_no=1

Fault plane solutions and seismic moments of four largest shallow events which occurred in the Antarctic Peninsula-Drake Passage region were redetermined by the moment tensor inversion method (FITCH et al. : J. Geophys. Res., 85,3817,1980) for body waves on WWSSN long-period records. The June 15,1970,event (Ms 7.0) is a large transform fault event along the North Scotia Ridge between the South America and the Scotia plates with a moment of 3.7×(10)^<26>dyn・cm. The February 8,1971,event (Ms 7.0) is a large normal faulting event with a moment of 2.4×(10)^<26>dyn・cm in the South Shetland Islands, north off the Antarctic Peninsula. The December 29,1975,event (Ms 6.5) is a vertical dip slip fault event with a moment of 0.7×(10)^<26>dyn・cm, which was located in the north of the Drake Passage and was probably associated with the spreading between the Antarctic and the Scotia plates (BARKER : Antarctic Geology and Geophysics, ed. by ADIE, 17,1972). The mid-plate event (Ms 6.2) of February 5,1977,is a reverse faulting with a moment of 0.5×(10)^<26>dyn・cm, which is one of the largest mid-plate events in the world. The direction of the maximum compression of the event is 100°-110° clockwise from the north and is coincident with the spreading directions at the Pacific-Antarctic Ridge and the Atlantic-Indian Rise.