2008年汶川8.0级地震地表垂直和水平位移场模拟计算分析

本文采用Okada及Steketee的断裂位错模型,从理论上计算了龙门山中央主断裂和前山断裂在汶川地震中逆冲和走滑错动形成的地表位移场,包括地表垂直和水平位移场的基本特征。并将计算结果与地震科考成果进行了比较,发现计算结果与现场地表变形考察结果在变化趋势上表现出一致性。同时通过计算揭示了断裂错动过程中离断裂一定范围内的地表位移场变化情况,计算结果表明断裂错动形成的地表垂直存在较大的空间不均匀性,且主要集中于断裂的端部即映秀、北川和青川附近,并且位移场在这些地方变化都较强烈。水平位移场主要集中于北川以北的地区,水平位移场的空间变化比较均匀。

Simulation of Vertical and Horizontal Displacement Fields of 2008 Wenchuan MS8.0 Earthquake

By using fault dislocation model proposed by Yoshimitsu Okada and Steketee, we calculate the vertical and horizontal displacements along Yingxiu-Beichuan reverse fault and Guanxian-Anxian reverse fault along which Wenchuan MS8.0 earthquake occurred in 2008. Comparing with the results from field survey along the surface rupture zone, we find that our computational results are comparable to the reality in displacement variation trend. Furthermore, the computational results indicate that the surface displacement fields varies with the distance form the fault, and the vertical displacement fields show strong inhomogeneity, in which largen displacement focuses on the ends of fault. However, in contrast to the vertical displacement, the horizontal displacement shows relative uniformity in space.