Toshihiko Shimamoto
Research
Research
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Shimamoto's considerable research on earthquake science has focussed on the results of high\-velocity friction experiments in a general aim to better understand frictional slip within earthquakes.

In 1997, while pursuing the understanding of how frictional melting affects fault instability, Shimamoto and his research team set up experiments to test Gabbro samples under high\-velocity. Initially at room temperature, the Gabbro was subject to slip rates from 7\.5 mm/s to 1\.8 m/s using a rotary\-shear high\-speed friction testing machine. Ultimately, two stages of slip weakening were apparent: one was found after the initial slip due to flash heating, the other after peak friction with the formation of a new molten layer along faults.

In 2011, Shimamoto and a team of researchers compared around 300 rotary shear apparatus experiments (both published and unpublished) to understand the implications of experimental data and its reliability in determining and prediciting friction at earthquake nucleation depths. Shimamoto and his team found that experimentally gathered data alongside field readings and samples suggest significant decrease in friction for both cohesive and non\-cohesive rocks at slip rates of 0\.1\-2\.6 m/sec. Regardless of material or weakening mechanism, fault lubrication was found to be constant during earthquakes.


How do high-velocity friction experiments contribute to understanding frictional slip within earthquakes?