Publication Date:
2014-04-04
Description:
It has been recently demonstrated that averaging the autocorrelations of fields produced by various almost-vertical incoming elastic body plane waves upon a layered system approximately leads to the imaginary part of the corresponding 1D Green’s functions for deep sources located underneath the receiver ( Kawase et al. , 2011 ). Thus, the ensemble of these waves from deep earthquakes recorded in a station located in the epicentral zone is interpreted as a diffuse field. In this short note, we extend the study to consider earthquakes recorded in a station located at epicentral distances of up to hundreds of kilometers. We consider the horizontal-to-vertical spectral ratio (HVSR) of the averaged P , S , and coda waves and full earthquake records at the Cibeles station (Mexico City Accelerometric Network) and compare these with the results obtained with the corresponding HVSR for the 1D ( Kawase et al. , 2011 ) and the 3D ( Sánchez-Sesma, Rodríguez, et al. , 2011 ) diffuse fields models. Using the signals of 90 earthquakes recorded at Cibeles, we find that the experimental results have distinctive features compatible with the 3D signature of a diffuse field. We interpret this result as a consequence of the multiple paths that seismic waves undergo from the subducting slab to the Mexico City valley and to the multiple scattering in a complex tectonic environment. Our study strongly suggests that we can use strong-motion records from earthquakes and apply similar techniques to the ones used to analyze the ambient seismic field. Online Material: Earthquake catalog.
Print ISSN:
0037-1106
Electronic ISSN:
1943-3573
Topics:
Geosciences
,
Physics
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