Seismic refraction and wide-angle reflection exploration by JARE-43 on Mizuho Plateau, East Antarctica

• Main Authors: Hiroki Miyamachi, Shigeru Toda, Takeshi Matsushima, Masamitsu Takada, Atsushi Watanabe, Mikiya Yamashita, Masaki Kanao
• Format: Report
• Language: English
• Published: Department of Earth and Environmental Sciences, Faculty of Science,Kagoshima University/Department of Earth Sciences, Faculty of Education,Aichi University of Education/Institute of Seismology and Volcanology, Faculty of Sciences, Kyushu University/Institute of Seismology and Volcanology, Graduate School of Science,Hokkaido University/Department of Earth and Planetary Sciences, Graduate School of Sciences, Kyushu University/Department of Polar Science, The Graduate University for Advanced Studies/National Institute of Polar Research 2003
• Subjects: velocity model,Antarctica,Mizuho Plateau,crust; Antarctic; East Antarctica; Austral; Mizuho; Mizuho Plateau; Prince Olav Coast; Antarc*; Antarctica; Ice Sheet; Polar geoscience
• Online Access: https://nipr.repo.nii.ac.jp/?action=repository_uri&item_id=3118; http://id.nii.ac.jp/1291/00003118/; https://nipr.repo.nii.ac.jp/?action=repository_action_common_download&item_id=3118&item_no=1&attribute_id=18&file_no=1

The 43rd Japanese Antarctic Research Expedition (JARE-43) carried out seismic exploration experiments on Mizuho Plateau,East Antarctica,in the austral summer season of ,2001-2002. The exploration was composed of seven large explosions and 161seismic stations distributed along the 151 km-long seismic line.The first arrival time data are analyzed by a refraction method.It is found that the ice sheet is composed of two layers:the upper layer with P wave velocity of 2.7-2.9 km/s has thickness of 35-45 m,and the lower layer with P wave velocity of 3.7-3.9 km/s continues to the bedrock.Lateral velocity variation in the upper-most crust is revealed:P wave velocity for the upper-most crust in the southern and central parts is 6.1-6.2 km/s and that in the northern part is5.9 km/s. This result implies that the geological boundary observed along the coast in the Lu tzow-Holm Bay and Prince Olav Coast regions possibly continues to the inland area.The S wave velocity is also obtained to be roughly 3.5km/s for the whole upper-most crust.Travel time analysis of two distinct reflection phases shows two horizontal reflecting planes located at 19 and 40km depth; the latter corresponds to the Moho discontinuity.