Coherent wavefield reconstruction improves event location with dense seismic arrays

Abstract

We propose a novel reconstruction method for coherent wavefields recorded by dense seismic arrays. The inherent spatio-temporal coherence in collocated time series is quantified by means of the semblance norm. Using field data recorded by the 1800-station LASSO array and realistic simulations, we demonstrate that the proposed method can reconstruct the wavefields well and produce more coherent and regularized waveform data with high signal-to-noise ratio. We further examine the effectiveness of the reconstructed and enhanced data with stacking-based seismic location. The comparison of imaging results for two synthetic and four field events demonstrates the superiority of reconstructed waveforms regarding source energy focusing and imaging resolution. Polarity-uncorrected traces of reconstructed waveforms produce high-resolution source images, and the corresponding short-term average to long-term average traces yield more stable source images with lower imaging resolution, suggesting the method’s applicability to a wide range of common imaging and monitoring tasks.