Retrieval and Validation of Reflections from Ambient Noise Green's Functions Using Synthetic Ground Motions and Active Source Experiment Results
Abstract
Researchers have successfully used ambient noise correlation techniques at global, regional, and local scales to extract information of the subsurface but few analyses attempt to validate the Green's function obtained. Recently, a dense array of three-component 10Hz geophones was deployed in northern Mexico for six hours, with the intention of analyzing the capabilities of these networks in the mapping of natural resources. We obtained Green's functions using ambient noise cross-correlations and then we compare them against synthetic seismograms obtained using FEM with a velocity model built using the reflectors and P-wave velocities reported from the active source experiments. S-wave velocities are constrained using values from several ambient noise techniques, such as SPAC, H/V, and seismic tomography. Preliminary results show that the Green's functions obtained with ambient noise techniques are similar to the synthetics from the 3D active model. As in many cases, surface waves dominate the ambient noise Green's functions, but in lower frequencies (1-5 Hz) body waves are more energetic. After the analysis, we apply traditional seismic reflection techniques and obtain similar results to the 3D model used for validation purposes. These results show that it is possible to use reflection techniques with Green's function obtained using ambient noise cross-correlations, enabling the exploration of sites where actives sources are not feasible. We can also evaluate the limitation of ambient noise Green's functions to plan better future array deployments.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFM.S13B2560R
- Keywords:
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- 7203 Body waves;
- SEISMOLOGYDE: 7219 Seismic monitoring and test-ban treaty verification;
- SEISMOLOGYDE: 7255 Surface waves and free oscillations;
- SEISMOLOGYDE: 7294 Seismic instruments and networks;
- SEISMOLOGY