Tectonic environment on the fault, such as temperature, pressure, pore fluid, and rock type, will cause diversity of seismic phenomena. Estimation of tectonic environments on the plate interface will be helpful to assess their effect on seismicity.

① Thermal structure in subduction zone ： Yabe et al. (2014, EPS)

In Hikurangi subduction zone, New Zealand, where the depth of tectonic tremor varies along strike, a thermal structure of the subduction zone is estimated based on the heat flow observations. Although the uncertainty of the estimation is large, it is not denied that tectonic tremor occurs along an isotherm depth of 350Cº.

② Seismic attenuation structure ： Yabe et al. (2014, BSSA), Yabe and Ide (2014, JGR), Yabe et al. (2019, JGR)

Seismic wave is attenuated during it propagates in the Earth. Information on seismic attenuation is important for ground motion prediction. In Nankai and Cascadia subduction zones, seismicity of regular earthquake is usually very low. Hence, the estimation of seismic wave attenuation is difficult. I have used seismic signals of tectonic tremors instead to estimate seismic attenuation. I have also compared it with seismic signals of intra-slab regular earthquakes. It may enable us to estimate seismic attenuation of subducting oceanic crust.