| Tectonically, earthquake is a kind of complex sliding frictional behavior of the fault zone in response to tectonic stress. The strain energy releasing pattern, releasing rate, the energy budget of the earthquake, the slipping motions are all associated with the frictional characteristics of the fault. The Wenchuan earthquake of May12,2008 along the Longmen shan fault zone is caused by relative thrust sliding friction between hanging wall and the footwall of Sichuan basin and BaYanKaLa block. Therefore, we carried out the frictional properties researches, including fault friction physical properties, the energy distribution of Wenchuan earthquake and spatial co-seismic slip distribution in fault plane.After temperature anomaly monitoring with high-precision platonic probe in WFSD-1 borehole, the results showed that the emperature measurement system satisfies the requirement of WFSD. We find the depth between 580 to 610m is the major slip zone, whose thermal diffusion characteristics are similar to the frictional temperature anomaly among the anomalies. We modeled the solution of one-dimensional conduction in an infinite medium of the temperature anomaly, and obtained the apparent frictional coefficient,μ=0.16-0.32, frictional strength,τ=3.0MPa. This numbers are smaller than the results from laboratory test, Considering the not entirely thermal equilibrium of the relative temperature gradient measurement, the convection caused by drilling fluid, fluid flow, thermal pressurization, fluid lubrication and other Weakening mechanisms that maybe lower the temperature anomaly amplitude.Finally, the frictional coefficient of 0.25 is determined, and friction heat also was estimated (EF=6.12×1018J) of the active fault.Based on achievement of rupture process researches of the domestic and foreign many research teams and experiential formula, we estimated radiated energy, ER=1.6×1016J. After measured the particle size distribution for the particle diameter range from several nm to 150μm of the major slip zone by using transmission electron microscope (TEM), scanning electron microscope (SEM), We identified the power law of the distribution and ascertain the surface fracture energy,8.82×1016J. Then the seismic efficiency of Wenchuan earthquake is calculated, just about 0.87%, the fractural efficiency is 1.41% and the frictional efficiency is 97.72%.So the energy budget above reveals that the elastic strain energy released mainly used to overcome the frictional shear resistance and lost as frictional heat. The tress drop of wenchuan earthquake are also calculated including apparent stress, static stress drop, and dynamic stress drop, which are 0.76MPa,7.64MPa and 4.58MPa, respectively. Take account of the characteristics energy budget and geological environment, the evolution of stress in seismic process and its happening mechanism are discussed. Additional, we tried to inverse co-seismic slip distribution of the sliding plane using GPS monitoring data, and achieved preliminary results, and then the method and model should be perfected in the future.
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