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Using Seismic and Gravity Measurements to Map the 3D Structure of the San Gabriel and San Bernardino Basins

Valeria Villa, Robert W. Clayton, & Patricia Persaud

Published August 12, 2020, SCEC Contribution #10413, 2020 SCEC Annual Meeting Poster #042

Sedimentary basins like the San Gabriel and San Bernardino basins in Southern California are thought to trap and amplify seismic waves because of the impedance contrast between rock layers and concave shape. With the low-velocity sediments connecting these basins to the Los Angeles basin, seismic energy can be channeled towards the densely populated downtown Los Angeles area. As part of the Basin Amplification Seismic Investigation (BASIN) project, we set out to incorporate the gravity data in these basins to provide further detail on the structure, thereby obtaining a 3-dimensional model of the subsurface structure. Here, we combine the sediment-basement interface obtained from P-to-S receiver functions (RFs) and Bouguer gravity data along seismic lines to determine the 2D structure along the profiles. The use of gravity allows us to properly connect layering that has been offset by faults (i.e. the Raymond Fault). We then interpolate these results along the profiles to produce a 3D structural model using gravity as a constraint. We demonstrate the potential of integrating gravity data to observe subtle faults in the sediment-basement interface, and for creating a 3D mesh of this interface across the San Gabriel and San Bernardino Basins.

Villa, V., Clayton, R. W., & Persaud, P. (2020, 08). Using Seismic and Gravity Measurements to Map the 3D Structure of the San Gabriel and San Bernardino Basins. Poster Presentation at 2020 SCEC Annual Meeting.

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