考虑地震动空间相关性及大震震源效应的烈度场插值方法

Intensity field interpolation method considering spatial correlation of ground motion and source effect of large earthquakes

摘要:

地震发生后,利用强震动观测数据快速生成合理的等震线图是地震烈度速报中的一项关键技术。基于震源参数及烈度衰减规律生成的烈度等震线过于规则,无法反映局部烈度分布特征；而直接采用观测数据通过插值生成的等震线无法合理反映大震的震源效应。为此,提出一种考虑地震动空间相关性及大震震源效应的烈度场融合克里金插值方法,利用点到点之间的距离来考虑烈度的空间相关性,利用点到源之间的距离来考虑大震的震源效应。首先,在克里金插值方法的框架下,使用粒子群优化算法实现半变异函数的快速自动拟合；其次,通过两种自变量不同的半变异函数拟合实现了对空间相关性和震源效应的考虑；最后,使用日本和中国地震数据的插值结果验证方法的合理性。结果表明,融合克里金插值方法获得的烈度等震线图形状规则,能反映出一次地震的震源效应,且对台站稀疏的情况有较好的适应性,满足地震烈度速报的要求。该方法可为地震烈度速报及地震烈度等震线的绘制提供技术支持。

Abstract:

After an earthquake occurs, it is a key technology to quickly generate a reasonable isoseismal map using strong motion observation data. The intensity isoseismal map generated based on source parameters and intensity attenuation law is too regular to reflect the local intensity distribution characteristics. However, the isoseismal map directly generated from the observed data by interpolation cannot reasonably reflect the source effect of large earthquakes. This article proposes an intensity field fusion Kriging interpolation method that considers the spatial correlation of seismic motion and the source effect of large earthquakes. The method utilizes the distance between points to consider the spatial correlation of intensity, and the distance between points to source to consider the source effect of large earthquakes. First, in the framework of Kriging interpolation method, Particle Swarm Optimization algorithm was used to realize the fast automatic fitting of semivariogram. Secondly, the consideration of spatial correlation and source effects was achieved through fitting two semivariogram functions with different independent variables. Finally, the interpolation results of earthquake data from Japan and China were used to verify the rationality of the method. The results show that the shape of the intensity isoseismal map obtained by the fusion Kriging interpolation method is regular, which can reflect the source effect of an earthquake, and has a good adaptability to the sparse situation of stations, meeting the requirements of rapid seismic intensity reporting. This method can provide technical support for rapid seismic intensity reporting and the drawing of seismic intensity isoseismal map.