2014年5月2日(金) 09:00 〜 10:45 313 (3F)

コンビーナ:*藤縄 幸雄(一般社団法人危機管理対策協議会)、芳原 容英(電気通信大学情報理工学部情報・通信工学科)、座長:藤縄 幸雄(一般社団法人危機管理対策協議会)、Huang Qinghua(Department of Geophysics, Peking University)

The microcrack has been widely investigated in various disciplines including seismology and geotechnical engineering communities. The disastrous natural events as earthquake, volcanic eruption or ground slide are considered as rupture of crust consisting of heterogeneous rocks. These rupture precede small cracks in the preparatory stage of main ruptures. The rupture of smallest scale accompanies the so-called acoustic emission (AE) providing means to investigate rupture process and to monitor the health check of the rocks. Recent years the investigation has extended to the seismo-electromagnetic phenomena especially to find precursors for short-term prediction. Moreover characteristics of the electromagnetic phenomena are suggested to open new windows to look into the state of the medium and rupture phenomena. The crust of the earth is elastic-porous medium filled with fluids as water. The research on the rupture had a remarkable progress in early 1990 contributing to interpret the mysterious seismoelectric phenomena associated earthquakes. Examples are 1) the faster propagation of co-seismic signal with velocity much larger than the p-wave, 2)the ULF band anomalies associated the slow-slip of subducting slab and 3)the converted electromagnetic mode at the material contrast for surveying oil and gas. And, 4) the electromagnetic method has been shown to detect micro-cracks preceding natural earthquakes suggesting that the nucleation stage can be identified. In this session we intend to summarize state of arts of investigation on microcrack in variety of disciplines to make further progress on the basis of new finding of phenomena and new techniques proposed. We hope to contribute to build more practical prediction method of earthquake, volcanic eruption, and ground-slide.