Multi-Data Rupture Imaging of the 2026 Northern Venezuela Mw 7.5 Earthquake: Strong Unilateral Propagation Along a Segmented Fault System
Liuwei Xu, Yunjun Zhang, Hongrui Wang, Chen Ji, Cunren Liang, Zhongwen Zhan, & Yuankun XuSubmitted August 30, 2026, SCEC Contribution #15348, 2026 SCEC Annual Meeting Poster #TBD
The Boconó and San Sebastián faults are the major onshore and offshore components of the Caribbean–South America plate boundary, but their connectivity and roles in hosting large earthquakes remain poorly constrained due to the region’s complex fault system and the limited instrumental record of the historical M~7 earthquakes that struck northern Venezuela. We investigated the rupture process of the 24 June 2026 Mw 7.5 earthquake using Slowness-Enhanced Back-Projection, teleseismic body waves, and multi-track Sentinel-1, NISAR, and ALOS2 line-of-sight displacements. High-frequency radiation and finite-fault models indicated a strongly asymmetric rupture that propagated predominantly eastward from the hypocenter. We represented the source using a segmented fault geometry and tested alternative fault positions, strikes, dips, and dipping directions. These tests showed that fault geometry strongly controlled the recovered slip distribution and its depth. The preferred model revealed a pronounced along-strike transition from a subvertical north-dipping fault near the hypocenter, through a near-vertical central section, to an approximately 73° south-dipping offshore section, providing a new constraint on the connection between the onshore Boconó Fault and the offshore San Sebastián Fault. A regional historical catalog identified two pre-2026 M7-class earthquakes in the studied corridor: the 1812 La Guaira M7.7 earthquake and the 1900 offshore Mw 7.6–7.7 earthquake, for which the San Sebastián Fault have been proposed to host coseismic slip. These events show that the broader plate-boundary zone repeatedly hosts large earthquakes, although available evidence does not demonstrate repeated rupture of the same fault segment. The 2026 rupture provides a modern geophysical framework for re-evaluating the source faults of historical earthquakes and indicates that regional hazard models should account for cascading rupture across geometrically distinct onshore and offshore segments.
Citation
Xu, L., Zhang, Y., Wang, H., Ji, C., Liang, C., Zhan, Z., & Xu, Y. (2026, 08). Multi-Data Rupture Imaging of the 2026 Northern Venezuela Mw 7.5 Earthquake: Strong Unilateral Propagation Along a Segmented Fault System. Poster Presentation at 2026 SCEC Annual Meeting.
Related Projects & Working Groups
Seismology
