32-8 Recent evidence of vertical and lateral variations of the cortical structure of the north-central region of the Gulf of California from seismic tomography

Session: 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 II)

Presenting Author:

Authors:

Abstract:

The Gulf of California Rift exhibits a heterogeneous distribution of rupture processes, from south to north, due to historical seismicity and differences in stress regimes. Several studies have identified geological, geophysical, and seismological differences from the south to the north region of the Gulf of California, with diffuse deformation occurring in the north. These differences are likely associated with the thinning and nature of the crust, which is still under discussion. In the southern Gulf of California, evidence shows a more developed oceanic crust, but there are differences from the central to the northern Gulf of California according to geophysical and seismological evidence. Despite these differences in the crust reported in some studies, few studies provide information on the physical properties of the crust and its lateral variations in this region. Tomographic studies using earthquakes have provided knowledge about mantle dynamics, revealed through variations in S-wave velocities, but they do not capture sufficient detail of the crust.

We analyzed 11 shallow earthquakes and one year of seismic noise data recorded by the seismic networks of CICESE and the National Seismological Service (SSN) to obtain the S-wave velocity model. We used a travel-time tomographic approach, different from conventional methods, which uses lateral constraints.

The three-dimensional S-wave velocity model clearly shows lateral and vertical variations related to the structural complexity of the crust. The most superficial low velocity regions coincide with basins with geothermal potential recognized in the northern Gulf of California by other studies. While the deep low velocity zones would be related to the activity of the upper mantle. The velocity transitions from the center to the north of the Gulf explain a large part of the magnetic and gravimetric observations, as well as variations in seismicity, energy released and heat flow identified in previous studies.

Geological Society of America Abstracts with Programs. Vol. 58, No. 3, 2026

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