Affiliation: | Geophysics, Department of Earth and Ocean Sciences, University of British Columbia, 129–2219 Main Mall, Vancouver, BC, Canada, V6T 1Z4. E-mail:; Geological Survey of Japan, 1‐1‐3, Higashi, Tsukuba, Ibaraki, 305‐8567, Japan ;Japan National Oil Cooperation, Technology Research Center, 1‐2‐2, Hamada, Mihama-ku, Chiba, 261‐0025, Japan |