Seasonal to Multiannual Creep Rate Changes Along the Hayward, Rodgers Creek, and Maacama Faults

Danielle Lindsay, Taka'aki Taira, & Roland Bürgmann

Submitted September 7, 2025, SCEC Contribution #14951, 2025 SCEC Annual Meeting Poster #TBD

Aseismic creep plays a crucial role in the seismic hazard associated with a given fault. Tectonic forces continuously load faults, and the amount of strain released through fault creep directly influences the amount of energy remaining in the system to drive large earthquakes. Creeping fault segments pose a lesser seismic hazard than fully locked faults by increasing the interval between large earthquakes or reducing the magnitude of potential events. Changes in the rate of fault creep reflect the state of stress acting on the slipping portion of that fault over short (e.g., slow slip events) and long (e.g., viscous relaxation) time scales, and therefore reflect the evolving seismic hazard associated with a fault throughout the seismic cycle.

We identify seasonal to decadal-scale changes in fault behavior on the Hayward, Rodgers Creek, and Maacama faults in northern California. We consider observations from an updated repeating micro-earthquake catalog, new surface creep rate estimates from InSAR, and existing terrestrial measurements from alignment arrays and creep meters. We process a 9-year ALOS-2 ScanSAR time series, which includes a 3-year period with near 14-day repeat intervals to constrain long-term surface creep rate estimates. Where C-band maintains coherence in urban areas, we complement the ALOS-2 with Sentinel-1 products and present seasonal creep variations in Willits, Santa Rosa, and along the Hayward Fault. Multi-annual creep rate changes along the Hayward Fault are imaged with Sentinel-1 time series and validated against creep meter time series. Decadal changes in Willits are highlighted with alignment array displacement time series and compared with changes in CRE productivity. This project utilized the newly released North America Surface Displacement (DISP) data product managed by the Jet Propulsion Laboratory's (JPL) Observational Products for End-Users from Remote Sensing Analysis (OPERA) project, as well as ALOS-2 ScanSAR data available through a JAXA-NASA data sharing agreement.

Citation
Lindsay, D., Taira, T., & Bürgmann, R. (2025, 09). Seasonal to Multiannual Creep Rate Changes Along the Hayward, Rodgers Creek, and Maacama Faults. Poster Presentation at 2025 SCEC Annual Meeting.

Related Projects & Working Groups
Tectonic Geodesy