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Nowcasting Earthquakes: Imaging the Earthquake Cycle in California with Machine Learning
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  • John B. Rundle,
  • Andrea Donnellan,
  • Geoffrey Fox,
  • James P Crutchfield,
  • Robert A Granat
John B. Rundle
University of California - Davis

Corresponding Author:[email protected]

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Andrea Donnellan
Jet Propulsion Laboratory, California Institute of Technology & University of Southern California
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Geoffrey Fox
Indiana University Bloomington
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James P Crutchfield
University of California
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Robert A Granat
City College of New York
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Abstract

We propose a new machine learning-based method for nowcasting earthquakes to image the time-dependent earthquake cycle. The result is a timeseries which may correspond to the process of stress accumulation and release. The timeseries is constructed by using Principal Component Analysis of regional seismicity. The patterns are found as eigenvectors of the cross-correlation matrix of a collection of seismicity timeseries in a coarse grained regional spatial grid (pattern recognition via unsupervised machine learning). The eigenvalues of this matrix represent the relative importance of the various eigenpatterns. Using the eigenvectors and eigenvalues, we then compute the weighted correlation timeseries (WCT) of the regional seismicity. This timeseries has the property that the weighted correlation generally decreases prior to major earthquakes in the region, and increases suddenly just after a major earthquake occurs. As in a previous paper (Rundle and Donnellan, 2020), we find that this method produces a nowcasting timeseries that resembles the hypothesized regional stress accumulation and release process characterizing the earthquake cycle. We then address the problem of whether the timeseries contains information regarding future large earthquakes. For this we compute a Receiver Operating Characteristic and determine the decision thresholds for several future time periods of interest (optimization via supervised machine learning). We find that signals can be detected that can be used to characterize the information content of the timeseries. These signals may be useful in assessing present and near-future seismic hazard.
Dec 2021Published in Earth and Space Science volume 8 issue 12. 10.1029/2021EA001757