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Ms. Qingyu Wang, PhD student at the Institut des Sciences de la Terre, U. of Genoble, presents “Ambient Noise-based Seismic Monitoring of the Evolution of Mechanical Properties of the Crust beneath Japan” at the MIT Earth Resources Laboratory.
Live video of this talk will be available on our Youtube channel: https://www.youtube.com/channel/UCj-nizf-7D28iIfFreLS1Xw
“The Japanese High Sensitivity Seismograph Network (Hi-net) contains more than 1000 permanent stations, which provide sizeable continuous data sets throughout Japan. We benefit from both short period and tilt meters data downhole recordings to measure the seismic velocity variations, in the objective to follow the mechanical evolution of the crust at different time scales with a temporal resolution from monthly to daily in different period ranges (1 – 50 s).
The short period results help us better understanding the environmental seismology on the subsurface processes under the impacts of some surrounding environmental forcing such as hydrology, thermo-elasticity, and some direct loading effects. We identify the different environmental factors in charge of some local, seasonal effects and show how better understanding these environmentally induced crustal perturbations improves the observations of tectonic-induced seismic property changes.
The long period study focuses on the response of the crust to the Mw 9.0, 2011 Tohoku-oki earthquake. Spatio-temporal evolution of seismic velocity changes in different period bands reveals depth-dependent seismic responses. The result could have implications of both nonelastic response of the crust to large strain changes and/or a complex response of crustal seismic velocities to transient fluid flow.”