Fiber-Imaged Supershear Dynamics in the 2024 Mw7 Mendocino Fault Earthquake

James W. Atterholt, Jeff J. McGuire, Andrew J. Barbour, Connie Stewart, & Morgan P. Moschetti

Submitted September 7, 2025, SCEC Contribution #14720, 2025 SCEC Annual Meeting Poster #TBD

Fault structure and rupture physics are deeply intertwined, and observations of this coupling are critical for understanding earthquake behavior. Rupture propagation is observable at fine scales using dense seismic networks. Fiber-optic sensing allows for long term deployments of ultra-dense arrays that enable high-resolution measurements of infrequent, large earthquakes. We record the 2024 Mw7 Mendocino Fault earthquake with a nearby fiber-optic array and image its behavior with seismic beamforming. The rupture propagates to the east at subshear velocity, stagnates near the Mendocino Triple Junction, a zone of structural complexity, and subsequently transitions to supershear velocity. The correlation between source physics and structure shows how lithospheric heterogeneity affects first-order characteristics of earthquake ruptures. Our results also demonstrate the potential for fiber-optic sensing to improve real-time estimation of key parameters for early warning.

Key Words
earthquake physics, supershear, early warning

Citation
Atterholt, J. W., McGuire, J. J., Barbour, A. J., Stewart, C., & Moschetti, M. P. (2025, 09). Fiber-Imaged Supershear Dynamics in the 2024 Mw7 Mendocino Fault Earthquake. Poster Presentation at 2025 SCEC Annual Meeting.

Related Projects & Working Groups
Seismology