Based on 60 records from the 20 stations within 100km to the epicenter of Lushan earthquake, the predominant period, period of peak response spectrum, duration of ground motion, and source duration are investigated. By the study, we conclude that within 100km to the epicenter, the scope of predominant period is 0.013~0. 275s in EW, NS and UD direction; the scope of period of peak response spectrum for 5% damping ratio is 0.03~0.65s; the scope of 90% ground motion durations is 5. 1~35. 9s; the scope of averaging source duration is 6.41 (EW), 6.05 (NS) and 5.47s (UD). Furthermore, based on the ground motion duration calculated by 20 stations dada, the predictive curve and equation of ground motion duration is regressed and compared with the recent equation of ground motion duration by Bommer (2009). We find that the ground motion durations of most stations are larger than predictively mean value by Bommer (2009), which means that the source effect of Lushan earthquake is relatively larger. Lastly, by the contour figure of ground motion duration and source duration, we conclude that the directivity character of duration is relatively apparent in NE direction. The relatively larger source duration and ground motion duration in NE direction indicate more energy release in the main shock of Lushan earthquake, which perhaps causes the relatively less aftershocks in this direction. The duration has no hanging wall effect, which perhaps results from the blind-reverse fault structure of Lushan earthquake.

This paper mainly studies the distribution of structural deformation and stress under the motion of thrust fault due to the effect of stress normal to the strike direction. As an example,we build the finite element model of central fault of Longmen Shan Fault zone,the Yingxiu-Qingchuan Fault. The finite element model is the model of single inverse fault. During the study,we compute the variations of surface deformation and stress fields near to the fault due to the thrust motion of Yingxiu-Qingchuan Fault in the process of Wenchuan earthquake. In the computation,we apply the frictional contact element and curved surface geometry to simulating the fault plane to obtain the variations of stress components and displacement field which are normal to strike direction and ground surface. In order to get the stress value of the hanging fall of the Yingxiu-Qingchuan Fault,we also apply the static dislocation model to the computation. Through the computation,we find that the displacement field along the strike direction can exist even if there is no initial stress load along the strike,but the value of this deformation is tiny. So we believe the displacement field along the strike may stem from the transverse deformation due to the extrusion of thrust fault; The structure deformation normal to the strike direction resulting from the thrust motion of inverse fault does not reach to maximum value at the zone near the fault,but the structure deformation normal to the ground surface can reach the maximum at the zone near to the fault; Generally,under the compression stress effect,the amount of crustal shortening is much bigger than that of uplift deformation at the zone near to the inverse fault,and the value of compression stress is much bigger than that of stress normal to ground surface along the fault plane. Furthermore,variation of stress on the inverse fault plane occurs mainly at the area where the dip angle of fault plane changes.

On 14 November 2001,an extraordinarily large earthquake(M_S 8.1)occurred on the Hoh Sai Hu segment of the eastern Kunlun Fault,northern Tibetan Plateau. The seismogenic fault,Hoh Sai Hu segment,is a left-lateral fault with a high slip rate in the geological history,and the average slip rate reaches(14.8±2.8)mm/a since the late Pleistocene. Different slip rates of Hoh Sai Hu segment can affect the fault motion in the future. So,the paper analyzes the effect of different slip rates and different initial friction coefficients on the fault surface of the Hoh Sai Hu segment of eastern Kunlun Fault on the rupture behaviors of the fault. In the research,we apply the single degree of spring block model controlled by the rate- and state-dependent frictional constitutive laws. Using the fault dislocation model and based on ancient earthquake researches,historical earthquakes data and the achievements of previous researchers,we obtained the parameters of the model. Through the numerical simulation of rupturing motion of the Hoh Sai Hu segment in the future 6500 years under different slip rates,we find that a faster annual slip rate will shorten the recurrence interval of earthquake. For example,the earthquake recurrence interval is 2100a at a slip rate of 0.014m/a,which agrees with previous research results,but,the recurrence interval will be 1000～1500a and 2100～2500a,corresponding to the slip rates of 0.018m/a and 0.008m/a,respectively. Slip rate of fault has no regular effect on the coseismic slip rate and displacement of fault in an earthquake. The initial friction coefficient on the fault surface has effect on earthquake recurrence interval. A smaller initial friction coefficient will lengthen earthquake recurrence interval. At the same time,the smaller initial friction coefficient will lead to larger slip rate and displacement of fault when earthquake occurs.

Basing on the fault dislocation model of Yoshimitsu Okada and Steketee and filed scientific investigation,we calculate theoretically space variation of the displacement fields,including vertical and horizontal displacements of the Wenchuan earthquake along the near zone(within 30km to the fault)of Yingxiu-Beichuan reverse fault.In the simulation,we interpret the space variation of the displacement field in the near zone of Yingxiu-Beichuan reverse fault in details.However,we can't describe the space variations in much detail by the field scientific investigation and limited data of GPS stations.Comparing with the results of field science investigation on surface rupture zone,our computational results show that the displacement fields have the same variation trend.At the same time,the displacement field declines drastically with distance to the outcrop of the fault,which agrees with the present research,and the velocity of this decline is much faster on the foot wall of fault than that on the hanging wall.By the simulation,we get the main conclusions:the vertical displacement of ground surface resulting from faulting in the earthquake shows the strong spatial inhomogeneity,and most large values of vertical displacement concentrate on the terminals of the fault,i.e.nearby Yingxiu and Beichuan.The displacement of the ground surface,including horizontal and vertical component,varies more drastically on both terminals of the fault than that of the middle section of the fault.The vertical displacement changes drastically along the direction of strike in the hanging wall of the fault than that of the foot wall.Except on the terminals of the fault,the horizontal displacement distributes homogenously in space.On the whole,except on the terminals of the fault,the amplitude of the displacement field on the hanging wall of the fault is larger than that of the foot wall.