Japan Geoscience Union Meeting 2015

Session information

International Session (Oral)

Symbol S (Solid Earth Sciences) » S-CG Complex & General

[S-CG15] Detection of microcracks prior to rupture and layered interfaces by the seismoelectronical method

Sun. May 24, 2015 3:15 PM - 4:00 PM 203 (2F)

Convener:*Yukio Fujinawa(Risk Control Associations), Yasuhide Hobara(Graduate School of Information and Engineering Department of Communication Engineering and Informatics, The University of Electro-Communications), Qinghua Huang(Department of Geophysics, Peking University), Niels Grobbe(TU Delft / Delft University of Technology), Chair:Niels Grobbe(Delft University of Technology), Yukio Fujinawa(Risk Control Associations)

The microcrack has been widely investigated in various disciplines including seismology and geotechnical engineering communities. Disastrous natural events such as earthquakes, volcanic eruptions or landslides are considered as ruptures of the Earth's crust consisting of heterogeneous rocks. These ruptures have been known to be preceded by small microcracks in the preparatory stage. They are accompanied by so-called acoustic emission (AE) and seismo- electromagnetic phenomena providing means to investigate the rupture process of earthquake and ground slides, rock bursts in mines, and health check of tunnels.
Moreover, seismoelectronics has been developed as new windows to determine physical parameters of the crust and its fluids in the geophysical exploration using active sources. The method has been used for detecting the electrical, hydraulic, and/or mechanical properties by measuring the mechanical energy conversion characteristics into electromagnetic energy at crustal macroscopic interfaces.
The research on the seismo-electromagnetic fields had a remarkable progress in the early 1990's. Examples are 1) the seismoelectric conversion generating an independently diffusing electromagnetic field at material contrasts for surveying for oil and gas, 2) the coupling between seismic and electromagnetic phenomena, 3) the ULF band anomalies associated the slow-slip of subducting slab, 4) the combination of both seismic resolution and electromagnetic (fluid) sensitivity, and 5) the possible detection of micro-cracks preceding natural earthquakes.
We intend to present state-of-the-art investigations on microcracks in a variety of disciplines, amongst which are new findings using seismoelectric phenomena and other new techniques for understanding of the microcracks preceding crustal ruptures. We hope to contribute in building a more practical short-term prediction method and in developing geophysical prospecting.