A Database of Ten Years of Prospective Next-Day Earthquake Forecasts in California from the Collaboratory for the Study of Earthquake Predictability

Francesco Serafini, José A. Bayona, Fabio Silva, Philip J. Maechling, & Maximilian J. Werner

In Preparation February 10, 2025, SCEC Contribution #14154

Short-term seismicity forecasting models are now routinely developed and used for Operational Earthquake Forecasting (OEF) by institutions and state agencies in several countries around the world. Forecasts used for these tasks should be rigorously tested against future observations, i.e., in a fully prospective fashion, to quantify the ability of their underlying model to forecast seismicity and thus build confidence around them. The Collaboratory for the Study of Earthquake Predictability (CSEP) operated twenty-seven M $\geq$ 3.95 automated seismicity models developed by nine different research groups around the world based on Italy, California, New Zealand, United Kingdom, and Japan. They produced over $50,000$ prospective daily forecasts for California between August 2007 and August 2018. Each forecast starts at 00:00:00 UTC, covers 24 hours, and is represented by the expected rates of earthquakes per bin in a pre-defined space-magnitude grid. In this article, we describe the database of forecasts, summarise their underlying models, and illustrate accessing and evaluating the forecasts against observed data and each other using a tutorial based on the pyCSEP toolkit for earthquake forecast developers. The forecasts are accessible to the public through Zenodo and provided code to evaluate them against observations. We use the PyCSEP Python library which facilitates access to the observations, as well as metrics for evaluation. This unprecedented database of fully prospective and automated earthquake forecasts provides a benchmark dataset for new model development and training that will underpin the next generation of OEF models.

Citation
Serafini, F., Bayona, J. A., Silva, F., Maechling, P. J., & Werner, M. J. (2025). A Database of Ten Years of Prospective Next-Day Earthquake Forecasts in California from the Collaboratory for the Study of Earthquake Predictability. Nature Scientific Data, (in preparation).