High-resolution hypocenter locations are most crucial in estimating seismic hazard, inferring Earth structure, studying tectonics, and to the fundamental understanding of the occurrence and physics of earthquakes. Several recent studies, of which this is a continuation, have demonstrated the substantial improvement in earthquake locations by applying a recently developed double-difference (DD) earthquake relocation algorithm to thousands of shallow earthquakes recorded at local distances. This project focuses on adapting the DD method to relocate, on a massive scale (several tens of thousands of events) and over large distances (thousands of km), earthquakes recorded at regional and teleseismic distances. The investigators will test and evaluate the performance of the new tools using globally recorded events for which ground truth is known, and compare the results with results derived from commonly used location techniques.
They will also apply the DD method to the 'groomed' ISC bulletin to relocate large numbers of earthquakes in subduction zones with the aim to image the internal structure of seismicity associated with descending slabs. The focus will initially be on the Andean subduction zone with the aim to define in detail the morphology of the slab and its correlation with patterns of microseismicity and the rupture areas of damaging earthquakes. they will also relocate other areas with dense seismicity to search for characteristic seismicity patterns in time and space which may provide new insights into the occurrence and physics of Wadati Benioff earthquakes.