张北地震在北京市激发的二维强地面运动的模拟

张北县距离北京市约200多km,1998年1月的张北地震是近期北京周边地区发生的一次较强规模的地震,研究它在北京地区引起的强地面运动,有助于分析首都圈内的地震危害性,为地震减灾提供理论帮助.本文利用新的计算工具-局域离散波数法,模拟了张北地震激发的包括来自上地壳、moho面反射波、首播等在内的全波场在北京西部引起的2D强地面运动,分析了该区内第三纪、第四纪沉积地层对于地震的放大效应,得出的主要结论有,薄的第四纪沉积盖层的地点放大效应比厚的第三纪盖层的大很多,说明介质物性是决定地点放大效应的根本原因;不同物性的沉积盖层,在R、Z分量上的放大作用不一样,体现了地点放大效应的复杂性,值得在今后的研究中继续探讨.

Simulation of strong ground motion in Beijing city due to the Zhangbei earthquake

The Zhangbei earthquake took place in January 1998 which is 200km away from Beijing city. Studying the strong ground motion in Beijing due to the Zhangbei earthquake can guide us to locate areas which would be destroyed heavily by earthquakes and provide information for reducing disaster of earthquakes. In the paper a new method local discrete wave-number boundary integral method is applied to simulate the strong ground motion in the west of Beijing due to full waves including reflection and refraction from upper lithosphere and the Moho. The site magnifying effect on Tertiary sediment and Quaternary sediment is analyzed and some conclusions are obtained which are helpful for further predicting earthquake disaster in the Beijing area. The most important conclusion is that the site magnifying effect is decided mostly by media parameters. It is larger in Quaternary sediment and shows different on Z and R components.