Institution: | 1. AIST, Institute of Geology and Geoinformation, Tsukuba, Ibaraki 305‐8567, Japan (email: otsubo‐m@aist.go.jp);2. Amaha High School, 229 Kazuma, Futtsu, Chiba 299‐1606, Japan;3. Department of Earth Sciences, Graduate School of Science, Chiba University, Chiba 263‐8522, Japan |