Usage of directional common image gathers for shallow seismic source localization

Accurate localization of shallow subsurface seismic events recorded by an array of receivers might be challenging given the near-surface complexity and its inadequate spatial sampling, low velocities, and limited frequency content. A novel approach that performs a joint localization and velocity analysis is presented. In this study, we utilize non-conventional migrated common image gathers as a tool for velocity and location analysis, based on the diffractive nature of the source. Only when the correct velocity model is used energy from all receivers is coherently focused at the true subsurface location. However, if the used model or CIG location is wrong, the migrated event does not have a flat moveout. The effectiveness of this technique is greatly improved by the use of vertical arrays of receivers. Through synthetic and real data examples, we show the usefulness of the method in a fully automatic workflow.