13th International Conference on Fracture June 16–21, 2013, Beijing, China -7- of melting, thawing, plastic flow, muds, and/or re-freezing. In other words, the seriously broken frozen soil layer maintained its frozen state during and a few days after the ground rupture and shock. From the site photograph 58 in Figure 4, it can be evidently observed that the frozen soil layer and the ice cover in a gully were largely uplifted, bended and then dislocated in tension and shear. The broken ice plates had fresh, sharp and angular sides and edges. There were no signs of melting, thawing, plastic flow, muds, and/or refreezing in the gully ice plates and frozen soils. In other words, the seriously broken frozen soils and ice plates maintained their frozen states during and a few days after the ground rupture and shock. Figure 4. The ice in a gully was displaced 1.4 m in left-lateral sense 25 km east of Kusai Lake (after photograph 58 of [17]) The above no melting and thawing phenomena in the broken and deformed permafrost soils and ice covers are typical and can be observed in almost all the 140 photographs collected in the Album [4]. Chen et al. [18] also observed that the earthquake ruptures in frozen soils mainly showed brittle deformation, were composed of shear fractures, tension fracture and seismic ridges. 4.3. Energy analysis for melting frozen soils Xu and Chen [19] carried out a temporal and spatial rupture process analysis of the earthquake by back-calculating the high signal-to-noise-ratio P-waveform data of vertical components of 20 stations with epicentral distances less than 900 km. Their back-calculated results showed that the earthquake had three sub-rupture events forming 220 km, 120 km and 270 km long fault ruptures. The six rupture speeds were 2.2 km/s to 5.8 km/s. Secondly, according to fracture mechanics, the energy required for the growth of the earthquake fracture (Efracture) in the rocks and soils may be estimated with the following equation.
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