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  Three-dimensional models of P wave velocity and P-to-S velocity ratio in the southern central Andes by simultaneous inversion of local earthquake data

Graeber, F. M., Asch, G. (1999): Three-dimensional models of P wave velocity and P-to-S velocity ratio in the southern central Andes by simultaneous inversion of local earthquake data. - Journal of Geophysical Research, 104, B9, 20,237-20,256.
https://doi.org/10.1029/1999JB900037

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 Creators:
Graeber, Frank M.1, Author
Asch, Günter2, Author              
Affiliations:
1Publikationen aller GIPP-unterstützten Projekte, Deutsches GeoForschungsZentrum, Potsdam, ou_44021              
22.4 Seismology, 2.0 Physics of the Earth, Departments, GFZ Publication Database, Deutsches GeoForschungsZentrum, ou_30023              

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 Abstract: The PISCO’94 (Proyecto de Investigatión Sismólogica de la Cordillera Occidental, 1994) seismological network of 31 digital broad band and short-period three-component seismometers was deployed in northern Chile between the Coastal Cordillera and the Western Cordillera. More than 5300 local seismic events were observed in a 100 day period. A subset of high-quality P and S arrival time data was used to invert simultaneously for hypocenters and velocity structure. Additional data from two other networks in the region could be included. The velocity models show a number of prominent anomalies, outlining an extremely thickened crust (about 70 km) beneath the forearc region, an anomalous crustal structure beneath the recent magmatic arc (Western Cordillera) characterized by very low velocities, and a high-velocity slab. A region of an increased Vp /Vs ratio has been found directly above the Wadati-Benioff zone, which might be caused by hydration processes. A zone of lower than average velocities and a high Vp /Vs ratio might correspond to the asthenospheric wedge. The upper edge of the Wadati-Benioff zone is sharply defined by intermediate depth hypocenters, while evidence for a double seismic zone can hardly be seen. Crustal events between the Precordillera and the Western Cordillera have been observed for the first time and are mainly located in the vicinity of the Salar de Atacama down to depths of about 40 km.

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Language(s): eng - English
 Dates: 1999
 Publication Status: Finally published
 Pages: -
 Publishing info: -
 Table of Contents: -
 Rev. Type: Peer
 Identifiers: DOI: 10.1029/1999JB900037
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Title: Journal of Geophysical Research
Source Genre: Journal, SCI, Scopus
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Pages: - Volume / Issue: 104 (B9) Sequence Number: - Start / End Page: 20,237 - 20,256 Identifier: CoNE: https://gfzpublic.gfz-potsdam.de/cone/journals/resource/journals268