线性单事件地震定位方法的改进及应用尝试

根据大震速报和快速预警实际需要，首先对Inglada线性单事件定位方法进行了适当的改进, 使其在仅有P波到时数据的情况下也能快速定位，且求解过程仅需简单迭代而不用奇异值分解; 其次， 尝试将改进后的方法从单层均匀模型引入到分层均匀模型中的近源台网定位情形，并通过单层均匀和分层均匀两种不同模型的理论实验讨论了该方法的可行性和适用范围; 最后整合了质量高且分布较好的距离2008年汶川M_S8.0地震震中最近的强震、微震, 以及川西流动台阵等观测记录资料，对汶川M_S8.0主震初始破裂点的时空参数进行了多种模型的定位实验. 结果表明, 改进后的线性单事件定位方法简单、快捷、易用，可广泛应用于近源地震定位，尤其是用于无法得到S波到时的中强以上直至巨大地震的速报、地震现场流动台网的快速定位以及地震的快速预警等. 

Improvement and case test of linear method for single event seismic location

Under the necessity of earthquake rapid reporting and early warning systems, we improve the Inglada linear method for single event seismic location. After this improvement, locating easily uses a simple iteration and mean algorithm instead of a complex singular value decomposition, and only four arrival times of P wave are essential. We also try to theoretically test this method from homogeneous velocity model to layered homogenous velocity model, so as to expand the application scope of the method. Combining with the 31 high-quality arrival times of direct P waves recorded at the near-field stations in Sichuan strong motion network, Sichuan regional seismic network, western Sichuan mobile array and Zipingpu reservoir seismic network, we practically relocate the main shock of Wenchuan M_S8.0 earthquake, and report the new parameters for this earthquake based on different velocity models. Theoretical tests show that this improved linear method is a simple, rapid and practical procedure for local earthquake location using a single-layer homogeneous crust model. It could be used for large earthquake rapid report, mobile seismic network fast location, and earthquake early warning for local earthquakes.