A robust method for determining moment tensors from surface microseismic data

Abstract

Summary We present a new method to determine moment tensors using surface microseismic imaging. The method involves the projection of data onto each moment tensor component, and using the amplitudes at the source origin time and location as an estimate of the seismic moment tensor. The procedure combines both precise source location and source characterization, and is known as Moment Tensor Microseismic Imaging (MTMI) (Chambers et al., in press). We compare the moment tensor results obtained using this method with those from a standard least squares inversion. We investigate the relative performance of the two approaches using synthetic data computed for two commonly observed microseismic source types, and a variety of signal to noise ratios (SNRs). MTMI proves to be significantly more robust at low SNRs. Moreover, we demonstrate a simple denoising technique that further increases our ability to determine the moment tensor in the presence of high noise.