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.