[S-CG61] Quest for the state & mechanism of subduction-zone earthquake through experiments across-scales

[SCG61-P06] In-operando friction experiments with synchrotron radiation towards unveiling the dynamic physico-chemical processes during earthquakes

*Takehiro Hirose¹, Jun Muto², Kazuyuki Yagi³ (1.Kochi Institute for Core Sample Research, Japan Agency for Marine-Earth Science and Technology, 2.Graduate School of Science, Tohoku University, 3.Graduate School of Engineering, Kyusyu University)

A fault experiences rapid movement at velocities exceeding meters per second during large earthquakes, inevitably generating heat as a result of friction on the fault surfaces. This heat triggers a variety of thermally activated physico-chemical processes such as gelification, melting and degassing, the products of which serve to lubricate the fault during the seismic event (Di Toro et al., 2011). However, these coseismic products form at fast-moving micro-contacts (i.e. asperities) and are instantaneously present at the onset of coseismic faulting, primarily as a result of non-equilibrium chemical reactions. The dynamic processes at these micro-contacts are therefore notoriously difficult to confirm without in-operando observation.

To confirm the existence of these metastable products formed at the micro-contacts, and to understand their mechanical effects on coseismic faulting, it is essential to establish a high-speed friction apparatus capable of reproducing coseismic faulting on a synchrotron beamline. Our aim is to redesign a pin-on-disk tribological apparatus, which has already been successfully developed for use at the beamline (Yagi et al., 2016 Tribol. Lett.), to accommodate experiments on geomaterials. The redesigned apparatus, in conjunction with synchrotron microtomography and X-ray diffraction studies, will allow us to gain greater insight into the dynamic physico-chemical processes involved during earthquakes. In our presentation, we will review previous studies on dynamic processes during coseismic faulting and outline our plans for the future apparatus of in-operando friction experiments with synchrotron radiation.