16:30 〜 16:45
[S12-2-01] Coupled interaction of deep Earth gases with quasi-static rupture of earthquake nuclei; possible source mechanism for seismo-EMs
invited
Various types of precursor anomalies preceding earthquakes have been reported in seismic, geodetic, geochemical and electromagnetic observations. Among them, recent advances in the seismo-EMs; especially GPS-TEC enhancements associated with strong earthquakes, represent a possible method by which to predict an imminent earthquake (Heki, GRL 2011). The underlying causal relationship still remain equivocal, although various proposals have been discussed on the topics.
In turn release of isotropic C13 and He3 influx from the deep crust reservoirs have been often detected; e.g. in the 2011 Tohoku-Oki earthquake (Sano et al. Nat. Comm. 2013). This fact suggests that the highly pressurized deep Earth fluids, as well as tectonic stress, play an important role in triggering of quasi-static rupture of earthquake nuclei. A new source mechanism for the seismo-EMs is needed to elucidate the underlying causal relationship between the hydro-mechanical and the electromagnetic processes.
Taking into account the coupled interaction of rock ruptures with the gas flowing-in as a working hypothesis (Enomoto, GJI 2012), we conducted laboratory experiments of uniaxial rock rupture with high-pressure CO2 flow, where a flat-ended chisel equipped with a flow-channel was loaded against a rock block of 15-30 mm thick; quartz diorite and gabbro. The electric currents as high as 0.2-0.7 microampere, depending on the rock thickness, were successfully measured, followed for approximately a few milliseconds after fully development of the crack. The current flows are transient process, and the following gases are un-electrified, but they drive the preceding electrified gases; i.e. generation of the pressure-impressed current dipole. The model provides well-reasoned explanation for geomagnetic anomalies as observed in the 1965-1967 Matsushiro earthquake swarm and in the 2011 Tohoku-Oki earthquake.
The author acknowledges the financial support from Genesis Research Institute, INC.
In turn release of isotropic C13 and He3 influx from the deep crust reservoirs have been often detected; e.g. in the 2011 Tohoku-Oki earthquake (Sano et al. Nat. Comm. 2013). This fact suggests that the highly pressurized deep Earth fluids, as well as tectonic stress, play an important role in triggering of quasi-static rupture of earthquake nuclei. A new source mechanism for the seismo-EMs is needed to elucidate the underlying causal relationship between the hydro-mechanical and the electromagnetic processes.
Taking into account the coupled interaction of rock ruptures with the gas flowing-in as a working hypothesis (Enomoto, GJI 2012), we conducted laboratory experiments of uniaxial rock rupture with high-pressure CO2 flow, where a flat-ended chisel equipped with a flow-channel was loaded against a rock block of 15-30 mm thick; quartz diorite and gabbro. The electric currents as high as 0.2-0.7 microampere, depending on the rock thickness, were successfully measured, followed for approximately a few milliseconds after fully development of the crack. The current flows are transient process, and the following gases are un-electrified, but they drive the preceding electrified gases; i.e. generation of the pressure-impressed current dipole. The model provides well-reasoned explanation for geomagnetic anomalies as observed in the 1965-1967 Matsushiro earthquake swarm and in the 2011 Tohoku-Oki earthquake.
The author acknowledges the financial support from Genesis Research Institute, INC.