Locating Strategy of Earthquake Rapid Report of Shandong Seismic Network—Taking the Shandong Ji'nan M4.1 Earthquake as an Example

Taking the M4.1 earthquake in Ji'nan as an example, we conducted an amount of phases recorded by 132 stations in Shandong with Hapsat, Simple and LocSAT methods. Meanwhile, we not only analyzed the influence on precise location between gap angle and the nearest station, but also indicated the relationship between the magnitude and epicentral distance. The results show that the nearest station in the regional network should be used and the combination of seismic phase time data with the smallest gap angle should be selected to determine the location of the epicenter during the rapid report of a major earthquake. If the near-field station failure and other special circumstances cannot meet the ideal state, it is appropriate to add more distant stations to reduce the gap angle to improve the positioning accuracy. In order to determine the magnitude of an earthquake. It is necessary to use the amplitude data of stations larger than 170 km to calculate the result reliably. If the magnitude value calculated by the nearer station is used, it will be smaller.