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We investigate in this study the impact of the Tohoku-Oki earthquake on Eastern China, and particularly focus on postseismic relaxation processes. We first invert for postseismic slip on the fault plane based on the GPS measurements of GEONET in Japan. Then, we use a layered rheological model to theoretically investigate the deep viscoelastic relaxation process. The Tohoku-Oki mainshock produced significant strain changes in Eastern China, dominantly east-west-oriented extension with a level close to or higher than the tectonic strain rates at the east border of China. The strain due to the postseismic stress relaxations has similar patterns as those produced by the mainshock, but with smaller magnitudes. The Tohoku-Oki earthquake impacts Eastern China for decades, but dominantly in the first 2-3 years after the mainshock and caused an apparent displacements and decrease of seismicity rate in Northeast China. For a long-term of 100 years, the Tohoku-Oki earthquake produces about 10 % of the tectonic strain rates in Eastern China, due to viscoelastic relaxation at the deep depth. [ABSTRACT FROM AUTHOR]

The rheological properties of most liquid in nature are between liquids and solids, including both elastic changes and viscosity changes, that is so-called 'viscoelastic'. Dynamic oscillatory test was used to quantitatively study the distinct viscoelastic behaviors of debris flow slurry in the shear stress conditions for the first time in this study. The debris flow slurry samples were from Jiangjiagou Ravine, Yunnan Province, China. The experimental results were found that at the low and middle stages of shearing, when the angular velocity ω<72.46 s, the loss modulus ( G″) was greater than the storage modulus ( G′), i.e. G″>G′. At the late stage of shearing, when the angular velocity ω≧72.46 s, the storage modulus was greater than or equal to the loss modulus, i.e. G′ ≧ G″, tan δ≦1 (where phase-shift angle δ= G″/G′), and the debris flow slurry was in a gel state. Therefore, the progress of this experimental study further reveals the mechanism of hyperconcentrated debris flows with a high velocity on low-gradient ravines. [ABSTRACT FROM AUTHOR]