Shallow velocity structure of Los Angeles Basin from ambient noise tomography with dense seismic arrays

Zhe Jia, & Robert W. Clayton

Published August 14, 2019, SCEC Contribution #9686, 2019 SCEC Annual Meeting Poster #051

It is important to understand the lateral variation of the sediment structure in the Los Angeles (LA) basin because the shallow velocity structure can amplify strong ground motions. The existing sediment models in the Los Angeles Basin are usually derived from sonic and industrial reflection profiles, but these models are limited in depth and the spatial distribution of the well sites and seismic lines. In this study, we show cross-correlation between five dense arrays and 21 continuous broadband stations, all of which are located in the Los Angeles Basin. Each SCSN station acts as a virtual source and the dense array stations are receivers. We observe clear fundamental and higher mode Rayleigh waves from the noise correlation functions with a frequency range (0.2-2.0 Hz) that is sensitive to the structures of top 2 km. Their rays cover a large portion of the Los Angeles Basin. We estimate the Rayleigh wave group velocities of the fundamental mode and first overtone, and determine shear wave velocity structure with seismic tomography.

Citation
Jia, Z., & Clayton, R. W. (2019, 08). Shallow velocity structure of Los Angeles Basin from ambient noise tomography with dense seismic arrays. Poster Presentation at 2019 SCEC Annual Meeting.

Related Projects & Working Groups
Seismology