41 Recent Advances in the Gulf of California Oblique Rift: Offshore and Onshore Studies // Avances Recientes en el Rift Oblicuo del Golfo de California: Estudios Marinos y Terrestres (Part III)

This session highlights recent research on the Gulf of California–Salton Trough plate boundary from ~12 Ma to today. We welcome terrestrial and marine studies involving tectonics, basin analysis, volcanology, sedimentology, and more. English or Spanish.

Friday, 24 April 2026
1:30 PM - 5:30 PM
LMH, Fiesta Terrace Salon

Vertical Coseismic Slip and Structural Analysis of the Central Laguna Salada Fault, Sierra Cucapá, Baja California.

Paper number: 41-3
Program: Technical Sessions
Time: 2:15 PM – 2:35 PM

Authors

Abstract

We present a structural, geomorphologic, and paleoseismic analysis that attempts to unravel the effects that the interactions between two active systems of extensional faults with opposite senses of tectonic transport exert on the Laguna Salada master fault (LSF). North of the LSF, and extending as far north as the northern Salton Trough, all the extensional faults are top-to-the-east and can be related to the West Salton Detachment system. South of the LSF, down to the southern Sierra El Mayor, comprises top-to-the-west faults associated with the Cañada David Detachment. The Quaternary alluvial fans along the LSF fault zone that controls the western margin of the Sierra Cucapá were systematically mapped, and coseismic offsets were analyzed by constructing 152 topographic profiles from high-resolution orthophotos and DEMs generated from drone surveys and LiDAR topography data collected after the 2010 Mw 7.2 EMC earthquake.

The results reveal that the deformation along the LSF is partitioned between two different fault strands separated by 500-600 m. The inner system is top-to-the-east, runs along the mountain front, and bounds the plutonic and metamorphic basement of the Sierra Cucapá. The outer system cuts the alluvial fan surfaces that lie over the basin fill. In the north, the outer strand curves to form a prominent releasing bend and merges with the inner bend over a distance of 12 km and then splays back into two or more distinct strands toward the international border. 

Vertical displacement recorded on ~ 700 coseismic scarps allows systematic patterns of faulting to be characterized along the strike of the LSF. Coseismic displacement increases systematically with the age of alluvial fan surfaces, which reflect the accumulation of distinct events through time. In fact, the abandonment of each fan surface was likely caused by the vertical uplift of each successive seismic event. In all, we recognizeat least six seismic events throughout the past ~ 2,050 years. Additionally, vertical slip is heterogeneously distributed along strike, and NE striking fault scarps generally record much greater vertical offset than NW striking fault scarps, which, in contrast, have much greater dextral offset. These patterns of slip are consistent with regional stress with NS-trending σ₁ close in magnitude to vertical σ₂, both of which are much greater than EW-trending σ₃. 

Geological Society of America Abstracts with Programs. Vol. 58, No. 3

doi: 10.1130/abs/2026CD-410813

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