| Description |
An approach for subspace detection and magnitude estimation of small seismic events is proposed. The process is used to identify mining related seismicity from a surface coal mine and an underground coal mining district, both located in the Western U.S. Using a blasting log and a locally derived seismic catalog as ground truth, the detector performance is assessed in terms of verified detections, false positives, and failed detections. Over 95% of the surface coal mine blasts and about 33% of the events from the underground mining district are correctly identified. The number of potential false positives are kept relatively low by requiring detections to simultaneously occur on two stations. Many of the potential false detections for the underground coal district are genuine events missed by the local seismic network, demonstrating the usefulness of regional subspace detectors in augmenting local catalogs. A trade-off in detection performance between stations at smaller source-receiver distances, which have increased signal to noise ratios, and stations at larger distances, which have greater waveform similarity, is observed. The increased detection capabilities of a single higher dimension subspace detector, compared to multiple lower dimension detectors, are explored in identifying events that can be described as linear combinations of training events. In this data set, such an advantage can be significant, justifying the use of a subspace detection scheme over conventional correlation methods. |
