Hidden structural linkages redefine the seismic hazard of the Garlock fault

Hao Zhang, Huiyun Guo, Matthew P. Salinas, James F. Dolan, & Zhongwen Zhan

Submitted August 30, 2026, SCEC Contribution #15229, 2026 SCEC Annual Meeting Poster #TBD

The extent to which dynamic earthquake ruptures propagate through structural discontinuities on faults is a fundamental determinant of earthquake magnitude and the related seismic hazard. While empirical criteria often rely on fault surface geometry, such frameworks often fail to capture complex structural connectivity at seismogenic depths. By intergrating structral geology, hydrology, and seismic observations augmented by machine learning and distributed acoustic sensing, we resolve the fine-scale architecture of a key extensional stepover on the Garlock fault. A previously underappreciated subsurface structure, the Cantil Valley fault, extends the overlap between two major segments of the Garlock fault and acts as both a primary hydraulic barrier and a mechanical boundary separating distinct stress regimes. This blind fault, alongside weakened strike-slip zones within the stepover, suggests substantially stronger inter-segment connection than previously inferred, implying that the usage of integrated, multi-physics subsurface imaging can constrain the upper limits of seismic hazard more robustly.

Key Words
Geolock Fault

Citation
Zhang, H., Guo, H., Salinas, M. P., Dolan, J. F., & Zhan, Z. (2026, 08). Hidden structural linkages redefine the seismic hazard of the Garlock fault. Poster Presentation at 2026 SCEC Annual Meeting.

Related Projects & Working Groups
Seismology