Probabilistic earthquake location in three-dimensional velocity models applied in Tengchong

The accuracy of earthquake location strongly depends on quality and consistency of available traveltime data. We obtained accurate automatic picks by employing optimized AICD automatic pickers and quality assessment scheme at temporary and permanent seismic networks surrounding Tengchong volcanic area. Based on those high-quality first-arrivals, we relocated 799 earthquakes with 1D （Hypomat） and 3D （probabilistic earthquake location） location algorithms. The comparison of 799 hypocenter relocations obtained by 1D location method （Hypomat） to those relocated in 3D velocity model using a probabilistic approach reveals no systematic shifts in epicenter locations but does exhibit large vertical shifts. 3D relocations are usually at the top of low velocity layers in crust and more clustered than 1D relocations. The events relocated with the 1D model seem often deeper than the events relocated with the 3D model. Relocating artificial sources and typical seismic sequences using 1D and 3D methods confirms that probabilistic earthquake location combined with 3D velocity model yields more precise hypocenter locations for Tengchong and has mean absolute errors of 0.7 km horizontally and 1.3 km vertically.