Physically motivated moment-tensor decomposition for mining-induced seismicity

TL;DR

This paper introduces a physically motivated method for decomposing mining-induced seismic moment tensors into interpretable components, providing criteria for unique decomposition and applying the approach to real seismic data.

Contribution

It develops a new geometric and physical framework for moment tensor decomposition specific to mining seismicity, addressing previous ambiguities and limitations.

Findings

Decomposition criteria based on source-type bounds are established.

A geometric scheme for closest tensor determination is proposed.

Application to seismic catalogs demonstrates practical utility.

Abstract

Abstract Compared to existing schemes, the decomposition of moment tensors for mining-induced seismic events into closing-crack and double-couple components has the advantage that each can be interpreted in terms of a physical source process (excavation convergence and slip/shear, respectively). Obviously, not every moment tensor permits such a decomposition, and we translate existing bounds on those that do to the Hudson source-type plot. For moment tensors falling within these bounds, it has previously been noted that there will be a infinite set of possible decompositions in general. We derive an implicit equation defining this set and suggest physically motivated criteria that can be used to select a single decomposition from it. Furthermore, for moment tensors falling outside the source-type bounds, we present a simple geometric scheme for determining the closest moment tensor within them (which can then be decomposed). To demonstrate the methods developed in this paper, we apply them to two catalogues of mining-induced seismicity.