Locating a scatterer in the active volcanic area of Southern Peru from ambient noise cross-correlation
We report on a strong scatterer of seismic energy in the 5–10 s period range located in the volcanic arc of Southern Peru. It is superficially like an active noise source in that it produces a continuous signal that arrives earlier than the inter-station surface wave in the noise cross-correlations. However, it is clearly determined to be a scatterer based on the coda arrivals observed in the cross-correlations, and the fact that it scatters waves from earthquake sources. We model the scatterer as a cylinder approximately 5 km in diameter with a shear wave velocity 30 per cent lower than the background velocity. It is likely to exist at the depth of 5–10 km, and is located at 71.6°W/16.1°S with an error of 10 km, which is near the inactive volcano Nevado Chachani and the active volcano El Misti which recently erupted in 1985.
Additional Information© 2013 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. Accepted 2012 December 5. Received 2012 November 3; in original form 2012 July 17. First published online: January 10, 2013. We thank Fan-Chi Lin at Caltech for providing many useful suggestions and thank Dunzhu Li at Caltech for providing the finite difference code. We also thank two anonymous reviewers for their helpful comments. Contribution number 212 from the Tectonics Observatory at Caltech. This work is supported by NSF (EAR-1045683) and the Gordon and Betty Moore Foundation.
Published - Geophys._J._Int.-2013-Ma-1332-41.pdf