Earthquake Statistics and Earthquake Research Studies in Pakistan

This paper is about short review of earthquake statistics and efforts for earthquake mitigation, hazard and risk assessment studies in Pakistan. Pakistan and adjoining region lying between longitude 60°E to 78°E and latitude 20°N to 45°N are selected for the study as this region has a history of many large earthquakes because of its location in the region of intersection of three plates namely Indian, Eurasian and Arabian Sea plate. This paper is based on the study of both seismological history of the region which includes recent and historical seismicity based on earthquake catalogue as well as geological knowledge supplemented with available fault system information. In this study, Pakistan and adjoining regions are divided into 14 seismogenic zones. Seismicity of each zone is studied considering also the major cities in the respective zone and type of infrastructure which is mainly responsible for earthquake disaster rather than earthquake itself.

可快速精确定位CFRP板冲击损伤的等时周向轨迹法

考虑碳纤维增强树脂基复合材料(Carbon fiber reinforced plastic,CFRP)板的纤维铺层对称性和导波传播各项异性,提出一种快速、定位精确的CFRP冲击损伤的等时周向轨迹定位方法。以损伤指数与仿真计算的方式,确定CFRP板周向导波传播速度与损伤反射波的飞行时间后,依据换能器、传感器与损伤位置之间的三角函数关系,计算既满足CFRP板中导波各个方向的传播速度又满足飞行时间的似然点。线性拟合似然点形成等时周向轨迹曲线样条,根据CFRP板的铺层对称性,镜像了轨迹曲线样条形成闭合的等时周向轨迹曲线,以三曲线交点实现损伤定位。以四点矩形阵列斜对角激励的方式进行CFRP板的冲击损伤检测实验。其实验结果表明,损伤引起损伤指数值的增幅显著,损伤反射波飞行时间可准确获得。拟合轨迹所需似然点数仅为155个,具有较小的计算量。等时周向轨迹定位法的定位误差可控,在期望误差下定位精度良好,未超出损伤区域。