Development of a SCEC Paleoseismic Database

Sally F. McGill, Kim D. Blisniuk, Michael E. Oskin, Kathy Barton, Ethan Failano, Annie Hinh, Angelika A. Jones, Miranda Owen, Thomas K. Rockwell, Sinan O. Akciz, Timothy Dawson, Scott T. Marshall, Belle Philibosian, Ian Pierce, Katherine M. Scharer, & Gordon G. Seitz

Submitted August 30, 2026, SCEC Contribution #15514, 2026 SCEC Annual Meeting Poster #TBD

Building on prior SCEC-funded efforts, we are compiling a paleoseismic database for the major strike-slip plate boundary faults in California. This work is a part of the UNREST TAG effort to develop an AI/ML-ready Digital Twin Fault System for California to test earthquake-cycle models against the observed paleoseismic record (see Oskin et al. abstract). The database will include the San Andreas, San Jacinto, Elsinore, Imperial, Garlock, Calaveras, San Gregorio-Hosgri and Hayward-Rodgers Creek-Maacama faults, which, collectively, carry >70% of plate motion. For each paleoseismic site, the database will include a .csv file containing the probability density functions (PDFs) for all paleoseismic events at the site, for use in testing, calibrating or constraining earthquake-cycle models or other models that rely on the dates of prehistoric earthquakes. These PDFs are obtained using the OxCal application, which first converts raw radiocarbon ages for the samples into calibrated calendar ages and then uses Bayesian statistics to calculate the posterior PDF for the age of each sample (whether from radiocarbon, luminescence or other dating technique) and for each paleoseismic event that lies between the samples, based on the ages of overlying and underlying samples. The database will also include the OxCal input code for each site, containing the a priori dates for each sample and the stratigraphic sequence of those samples. OxCal files will be gathered from the data supplements of published paleoseismic studies (when available) or will be constructed from the data and interpretations found in published studies, with review by the study author. The database will also include summary data for each site, such as latitude and longitude, time-period spanned by the record, number of paleoseismic events recognized, average recurrence interval, coefficient of variation for the recurrence interval, reference(s) to the source(s) of information used to compile the record, and the type of source (e.g., peer-reviewed journal, thesis or dissertation, consultant’s report, etc.). We will focus on peer-reviewed studies, but may include other sources, especially for fault sections in which peer-reviewed studies are lacking. We also present a significantly updated Geological Slip Rate Database (GSRD) with updated web-based tools, a new homepage, and Zenodo archive.

Key Words
paleoseismology, database, probability density function, prehistoric earthquake ages

Citation
McGill, S. F., Blisniuk, K. D., Oskin, M. E., Barton, K., Failano, E., Hinh, A., Jones, A. A., Owen, M., Rockwell, T. K., Akciz, S. O., Dawson, T., Marshall, S. T., Philibosian, B., Pierce, I., Scharer, K. M., & Seitz, G. G. (2026, 08). Development of a SCEC Paleoseismic Database. Poster Presentation at 2026 SCEC Annual Meeting.

Related Projects & Working Groups
Community Earth Models (CEM)