Pre-earthquake signals from geomagnetic total intensity analysis
Speaker: Chun-Rong Chen
Abstract
Some possibly precursory phenomena of big earthquake has detected including changes in seismicity, geochemistry, electromagnetic field, and geomagnetic. If pre-seismic variations in the geomagnetic field can be detected, it is important to investigate the relation between geomagnetic and earthquakes. Such variations would also provide information on the physical state of the Earth prior to the event. F. T. Freund (2007) has produce an interest experimental that find out the conductivity of rock both unload and load by pressure. As his result, the rock which is loaded has significant increase in conductivity and interacting to the other part which is unloaded and act like battery. This is a possible explanation of the anomaly in the geomagnetic. In order to distinguish the local change which is arose from tectonic active, a simple difference in spatial scale is a useful criterion. However this method is somewhat crude when seeking to detect variations as small as nanotesla. We use the total geomagnetic field models as substitution. ˇ§NOCsˇ¨ (Fujiwara et al. 2001) is a suitable model for our requirement. Put this method into Japan geomagnetic total field analysis during Kobe earthquake. It is an obvious anomaly before the big earthquake. The result is that this method is a useful manner to analysis geomagnetic total intensity.
Reference
Ken'ichi Yamazaki, Shin'ya Sakanaka, 2011. Localized changes in geomagnetic total intensity values prior to the 1995 Hyogo-ken Nanbu (Kobe) earthquake. Journal of Geodynamics 51, 37-43.
Satoshi Fujiwara, Teruaki Nishiki, Hiroki Shirai, Hideo Hamzaki, and P. Golovkov, 2001. Modeling the daily mean values of regional total force field changes in Japan. Earth Planets Space 53, 69-73.