The Los Angeles Basin Shape and its Underlying Shallow Moho

Valeria Villa, Robert W. Clayton, Fan-Chi Lin, & Heather A. Ford

Published September 8, 2024, SCEC Contribution #13758, 2024 SCEC Annual Meeting Poster #029

The sedimentary basin underneath the megalopolis of Los Angeles intensifies seismic motions and prolongs the shaking duration. Characterizing the basin’s shape, which in this case, is quite distorted due to its complicated formation, is necessary to predict the strong motions of large earthquakes such as the potential M8 southern San Andreas earthquake. We developed and applied a novel algorithm to identify basement and Moho P-to-S converted phases in receiver functions across widely scattered seismic stations. Typically, this is challenging due to phase incoherency, but we overcame it by integrating gravity measurements. Our results show that the basin resembles an oblong bowl and features a flatter southern side, a pronounced curve on the northern side, a sharp vertical offset on the eastern side, and a gradually sloping western side. The large size of the basin at a maximal depth of 10 km causes the Moho to uplift and resemble an inverted version of the basin. Our findings not only reveal the shape of the basin and extent of crustal thinning from the shallow Moho, but also provide insights for reconstructing its evolution.

Key Words
Sedimentary Basin, Los Angeles, Moho

Citation
Villa, V., Clayton, R. W., Lin, F., & Ford, H. A. (2024, 09). The Los Angeles Basin Shape and its Underlying Shallow Moho. Poster Presentation at 2024 SCEC Annual Meeting.

Related Projects & Working Groups
Seismology