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The Scattering Signal in Ambient Noise Correlation

Session: Waveform Cross-Correlation-Based Methods in Observational Seismology [Poster]

Type: Poster

Date: 4/21/2021

Presentation Time: 03:45 PM Pacific

Description: 

The ambient noise correlation has been a powerful tool to extract seismic signals. Often the correlation function contains a direct wave Green’s function and a strong scattered signal due to discontinuities in the medium. The direct wave Green’s function contains the travel time information and can therefore be used for tomography. The scattering signal can be used to locate abrupt discontinuities such as steep structural boundaries or faults.

Between 2017 and 2019, several dense arrays were deployed in the San Gabriel basin and San Bernardino Basin. We have correlated both dense array-dense array station pairs and dense array-broadband station pairs. In the correlation function, both direct wave Empirical Green’s Function and scattering signal can be observed. We extracted the surface wave dispersion curve from the direct wave Green’s Function to construct the velocity model, using Rayleigh and Love waves, with both fundamental mode and first-higher mode. We have initially use group velocities but plan to include phase velocities to improve the resolution. Using the velocity model from direct wave Green’s function, we developed an approach to invert for the near field noise source distribution using the scattering signal. The inverted noise source distribution, shows a strong spatial correlation with the fault structure and the basin edges. This technique provides a new method for locating faults, some of which may have no surface expression.

Presenting Author: Yida Li

Student Presenter: Yes

Authors