Detection of Hidden Low-Frequency Earthquakes in Southern Vancouver Island with Deep Learning

Authors

  • Jiun-Ting Lin Lawrence Livermore National Laboratory, Livermore, CA, USA
  • Amanda Thomas Department of Earth Sciences, University of Oregon, Eugene, OR, USA
  • Loïc Bachelot Department of Earth Sciences, University of Oregon, Eugene, OR, USA
  • Douglas Toomey Department of Earth Sciences, University of Oregon, Eugene, OR, USA
  • Jake Searcy School of Computer and Data Sciences, University of Oregon, Eugene, OR, USA
  • Diego Melgar Department of Earth Sciences, University of Oregon, Eugene, OR, USA

DOI:

https://doi.org/10.26443/seismica.v2i4.1134

Keywords:

Low frequency earthquake, deep learning, slow slip event, Cascadia Subduction Zone, Tremor

Abstract

Low-frequency earthquakes (LFEs) are small-magnitude earthquakes that are depleted in high-frequency content relative to traditional earthquakes of the same magnitude. These events occur in conjunction with slow slip events (SSEs) and can be used to infer the space and time evolution of SSEs. However, because LFEs have weak signals, and the methods used to identify them are computationally expensive, LFEs are not routinely cataloged in most places. Here, we develop a deep-learning model that learns from an existing LFE catalog to detect LFEs in 14 years of continuous waveform data in southern Vancouver Island. The result shows significant increases in detection rates at individual stations. We associate the detections and locate them using a grid search approach in a 3D regional velocity model, resulting in over 1 million LFEs during the performing period. Our resulting catalog is consistent with a widely used tremor catalog during periods of large-magnitude SSEs. However, there are time periods where it registers far more LFEs than the tremor catalog. We highlight a 16-day period in May 2010, when our model detects nearly 3,000 LFEs, whereas the tremor catalog contains only one tremor detection in the same region. This suggests the possibility of hidden small-magnitude SSEs that are undetected by current approaches. Our approach improves the temporal and spatial resolution of the LFE activities and provides new opportunities to understand deep subduction zone processes in this region.

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Seismica cover image for Volume 2, Number 4: The Cascadia Subduction Zone: Grand Challenges and Research Frontiers. Image shows a hemispherical white dome on a four-legged stand on a rocky mountain peak. In the far distance, a series of sharp rocky and snowy peaks stretches toward the setting sun which is refracted through thin clouds.

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Published

2024-10-18

How to Cite

Lin, J.-T., Thomas, A., Bachelot, L., Toomey, D., Searcy, J., & Melgar, D. (2024). Detection of Hidden Low-Frequency Earthquakes in Southern Vancouver Island with Deep Learning. Seismica, 2(4). https://doi.org/10.26443/seismica.v2i4.1134

Issue

Vol. 2 No. 4: Special Issue: the Cascadia Subduction Zone

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Special Issue: the Cascadia Subduction Zone

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Copyright (c) 2023 Jiun-Ting Lin, Amanda Thomas, Loïc Bachelot, Douglas Toomey, Jake Searcy, Diego Melgar

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