Ability of a global three‐dimensional model to locate regional events

We assess the ability of a global three‐dimensional (3D) seismic model of the crust and upper mantle (CUB2.0) to locate seismic events using regional travel time data alone (epicentral distances <20°). Assessments are based on a “ground truth” (GT) database, comprising nearly 1000 uncommonly well‐located events which occur in 23 event clusters across Eurasia and North Africa, groomed P and P n arrival time data observed at regional distances from individual events, and ∼1000 empirical phase path anomalies produced from event clusters. Evidence is presented that supports the conversion of the shear velocities ( v s ) in CUB2.0 to compressional velocities ( v p ) in the upper mantle using the thermoelastic properties of an assumed mantle composition rather than traditional empirical scaling relationships. Two principal results are presented. First, this 3D v p model fits the empirical P and P n phase path anomalies very well in both pattern and absolute level. Second, location assessments demonstrate that intrinsic regional location accuracy is ∼5 km using the 3D v p model and ∼10 km using the 1D model AK135. These findings highlight the importance of GT databases in assessing regional travel time models and establish that a global 3D v s model, together with v p inferred from it, provides a solid basis on which to build improvements in regional location capabilities.