Event locations: Speeding up grid searches using quadratic interpolation

Abstract: "The grid search method is a common approach to estimate the three spatial coordinates of event hypocenters. However, locating events in large search spaces with small grid spacings is computationally prohibitive.

This study accelerates the grid searches over large search spaces using a quadratic interpolation technique. We start with the coarse-grid-estimated location, where we have the minimum value of the difference in the traveltimes between S- and P-waves summed over all receivers. Then, we select the neighbouring grid points and build a 3D quadratic function.