Browsing by Autor "Ryan Porter"

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    Ambient noise tomography across the Central Andes
    (Oxford University Press, 2013) Kevin M. Ward; Ryan Porter; G. Zandt; S. L. Beck; L. S. Wagner; E. Minaya; Hernando Tavera
    The Central Andes of southern Peru, Bolivia, Argentina and Chile (between 12°S and 42°S) comprise the largest orogenic plateau in the world associated with abundant arc volcanism, the Central Andean Plateau, as well as multiple segments of flat-slab subduction making this part of the Earth a unique place to study various aspects of active plate tectonics. The goal of this continental-scale ambient noise tomography study is to incorporate broad-band seismic data from 20 seismic networks deployed incrementally in the Central Andes from 1994 May to 2012 August, to image the vertically polarized shear wave velocity (<it>V</it><inf>sv</inf>) structure of the South American Cordillera. Using dispersion measurements calculated from the cross-correlation of 330 broad-band seismic stations, we construct Rayleigh wave phase velocity maps in the period range of 8–40 s and invert these for the shear wave velocity (<it>V</it><inf>sv</inf>) structure of the Andean crust. We provide a dispersion misfit map as well as uncertainty envelopes for our <it>V</it><inf>sv</inf> model and observe striking first-order correlations with our shallow results (∼5 km) and the morphotectonic provinces as well as subtler geological features indicating our results are robust. Our results reveal for the first time the full extent of the mid-crustal Andean low-velocity zone that we tentatively interpret as the signature of a very large volume Neogene batholith. This study demonstrates the efficacy of integrating seismic data from numerous regional broad-band seismic networks to approximate the high-resolution coverage previously only available though larger networks such as the EarthScope USArray Transportable Array in the United States.
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    Erratum: Ambient noise tomography across the Central Andes
    (Oxford University Press, 2013) Kevin M. Ward; Ryan Porter; G. Zandt; S. L. Beck; L. S. Wagner; E. Minaya; Hernando Tavera
    Kevin M. Ward,1 Ryan C. Porter,2 George Zandt,1 Susan L. Beck,1 Lara S. Wagner,3 Estela Minaya4 and Hernando Tavera5 1Department of Geosciences, The University of Arizona, 1040 E. 4th Street Tucson, AZ 85721, USA. E-mail: wardk@email.arizona.edu 2Department of Terrestrial Magnetism, Carnegie Institution of Washington, 5241 Broad Branch Road, NW, Washington, DC 20015-1305, USA 3Department of Geological Sciences, University of North Carolina at Chapel Hill, 104 South Rd., Mitchell Hall, CB #3315, Chapel Hill, NC 27599-3315, USA 4El Observatorio San Calixto, Calle Indaburo 944, Casilla 12656, La Paz, Bolivia 5Instituto Geofisico Del Peru, Calle Badajo No. 169, Urb. Mayorazgo IV Etapa, Lima, Peru