1. Institute of Seismology and Volcanology, Faculty of Science Kyushu University Fukuoka Japan
2. School of Science Tokyo Institute of Technology Tokyo Japan
3. Earthquake Research Institute University of Tokyo Tokyo Japan
4. Aso Volcanological Laboratory, Institute for Geothermal Sciences, Graduate School of Science Kyoto University Kumamoto Japan
5. Geological Survey of Japan National Institute of Advanced Industrial Science and Technology Tsukuba Japan
6. Now at Oyo Co. Tokyo Japan