Applicability of 3D Modeling Techniques in Creating Single-Station Locations: A Test Case in Southern Asia

Conventional multistation location estimation is not possible for small earthquakes and explosions recorded at only a single seismic station. We present a novel method of estimating epicentral distance by integrating observed travel times (Lg-Pn and Sn-Pn) measured on three-component (3C) single-station data with theoretical travel times for the same phase combinations determined from 3D velocity models. Theoretical travel times for the body-wave phases are estimated using raytracing through a 3D P- and S-wave velocity model, while the travel times for Lg are estimated either using raytracing techniques or with a constant velocity determined from synthetics. Backazimuths are determined by applying polarization techniques on 3C data. The backazimuth and distance are then used to determine the epicenter for the event. The results of applying this 3D single-station location methodology to well-located events in southern Asia show mislocation errors that are typically less than 6% of the total propagation path distance.