Determination of the Focal Depth of the 2013 Liaoning Dengta MS5.1 Earthquake Using the First-Arrival Seismophase Location Method
Based on the observational data from the Liaoning seismic network from 2009 to 2022,the travel time curve for Pg waves of minor earthquakes in the Liaoning area was fitted,resulting in an upper crustal P-wave velocity of 6.11 km/s,and a dual-layer crustal P-wave velocity model for the region was constructed.Twenty clear Pg and nine Pn phase arrivals from official observation reports were extracted.Using the first arrival seismophase location method,the focal depth of the 2013 Liaoning Dengta MS5.1 earthquake was determined to be 10.8 km,with a minimum travel time residual for the initial P phase of 0.31 s.Using a location al-gorithm that considers errors,the focal depth was determined to be 10.27 km,with a location residual of 0.35 s,which is essentially consistent with the focal depth calculated using other velocity models,indicating high reliability.The analysis suggests that the focal depth of the Dengta MS5.1 earthquake is around 11 km.Using this depth as the main input parameter,the displacement and strain fields produced in the surroundings were calculated,showing typical characteristics of a strike-slip earthquake.
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