Are Regionally Calibrated Seismicity Models More Informative than Global Models? Insights from California, New Zealand, and Italy

Jose A Bayona*, William Savran, Pablo Iturrieta, Matthew Gerstenberger, Kenny Graham, Warner Marzocchi, Danijel Schorlemmer, Max Werner

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

2 Citations (Scopus)

Abstract

Earthquake forecasting models express hypotheses about seismogenesis that underpin global and regional probabilistic seismic hazard assessments (PSHAs). An implicit assumption is that the comparatively higher spatiotemporal resolution datasets from which regional models are generated lead to more informative seismicity forecasts than global models, which are however calibrated on greater datasets of large earthquakes. Here, we prospectively assess the ability of the Global Earthquake Activity Rate (GEAR1) model and 19 time‐independent regional models to forecast M 4.95+ seismicity in California, New Zealand, and Italy from 2014 through 2021, using metrics developed by the Collaboratory for the Study of Earthquake Predictability (CSEP). Our results show that regional models that adaptively smooth small earthquake locations perform best in California and Italy during the evaluation period; however, GEAR1, based on global seismicity and geodesy datasets, performs surprisingly well across all testing regions, ranking first in New Zealand, second in California, and third in Italy. Furthermore, the performance of the models is highly sensitive to spatial smoothing, and the optimal smoothing likely depends on the regional tectonic setting. Acknowledging the limited prospective test data, these results provide preliminary support for using GEAR1 as a global reference M 4.95+ seismicity model that could inform eight‐year regional and global PSHAs.
Original languageEnglish
JournalThe Seismic Record
Volume3
Issue number2
DOIs
Publication statusPublished - 6 Apr 2023

Keywords

  • Software development
  • Reproducibility of results
  • Earthquake interaction, forecasting, and prediction
  • Statistical seismology
  • Probabilistic forecasting

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