Controls on the Connected, Multistage 2026 Mw 7.6 Venezuela Earthquake from EKI MultiCMT, 3D Dynamic Rupture Modeling, NISAR and ALOS-2 InSAR analyses
Alice-Agnes Gabriel, Jeremy Wing Ching Wong, Rubi M. Garcia-Gonzalez, Eitan Rapaport Bruck, Mathilde Marchandon, Molly Zebker, Baoning Wu, Yohai Magen, Claudia Abril, David T. Sandwell, Yuri Fialko, & Wenyuan FanSubmitted August 30, 2026, SCEC Contribution #15602, 2026 SCEC Annual Meeting Poster #TBD
The destructive 2026 Mw 7.6 Venezuela earthquake ruptured the Boconó and the San Sebastián fault systems, causing more than 5,000 fatalities. Initial reports suggested a doublet: an Mw 7.2 event ~30s before the Mw 7.5 mainshock. We integrate inversions of NISAR and ALOS-2 InSAR data, Ensemble Kalman inversion for multiple centroid moment tensors (EKI-MultiCMT), teleseismic backprojection, and 3D dynamic rupture simulations to resolve fault geometry, slip distribution, and rupture evolution.
Our analyses favor a continuous, subshear rupture with several distinct episodes of moment release. InSAR resolves continuous deformation and three high-slip regions, one near La Guaira. EKI-MultiCMT identifies eight connected subevents, while backprojection tracks continuous eastward migration from Boconó to San Sebastián. During the first 40s, rupture radiates weak teleseismic P waves and releases only 36% of the total moment. A high-frequency burst at 48s marks the transition to the dominant moment release phase.
An ensemble of dynamic rupture simulations links this multistage evolution to fault geometry and regional stress. We optimize segment-varying dynamic prestress ratios using displacements and the moment-rate function. We prescribe a smooth west-to-east clockwise rotation of the regional stress field. Without imposing along-strike frictional or stress heterogeneity, the preferred model reproduces the first-order deformation and moment-rate evolution well. The Boconó fault is less favorably oriented, suppressing early moment release and decelerating but not arresting rupture. In contrast, the San Sebastián fault promotes reacceleration, dominant moment release, and surface rupture.
Together, we reinterpret the apparent doublet as one connected, multistage rupture with at least three episodes of moment release. Fault orientation relative to regional stress generates large variations in moment release without rupture arrest. High slip near La Guaira likely amplified the earthquake’s destructive impact. This earthquake demonstrates that connected continental strike-slip fault systems can host long ruptures with variable moment release, highlighting the need to include fault geometry, regional stress, and rupture connectivity in seismic hazard assessment.
Citation
Gabriel, A., Wong, J., Garcia-Gonzalez, R. M., Rapaport Bruck, E., Marchandon, M., Zebker, M., Wu, B., Magen, Y., Abril, C., Sandwell, D. T., Fialko, Y., & Fan, W. (2026, 08). Controls on the Connected, Multistage 2026 Mw 7.6 Venezuela Earthquake from EKI MultiCMT, 3D Dynamic Rupture Modeling, NISAR and ALOS-2 InSAR analyses. Poster Presentation at 2026 SCEC Annual Meeting.
Related Projects & Working Groups
Fault and Rupture Mechanics (FARM)
