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Titolo:
Attenuation tomography in the western central Andes: A detailed insight into the structure of a magmatic arc
Autore:
Haberland, C; Rietbrock, A;
Indirizzi:
Geoforschungszentrum Potsdam, Sect 2 4, D-14473 Potsdam, Germany Geoforschungszentrum Potsdam Potsdam Germany D-14473 73 Potsdam, Germany Univ Potsdam, Inst Geowissensch, D-14415 Potsdam, Germany Univ Potsdam Potsdam Germany D-14415 wissensch, D-14415 Potsdam, Germany
Titolo Testata:
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
fascicolo: B6, volume: 106, anno: 2001,
pagine: 11151 - 11167
SICI:
0148-0227(20010610)106:B6<11151:ATITWC>2.0.ZU;2-C
Fonte:
ISI
Lingua:
ENG
Soggetto:
SOUTHERN CENTRAL ANDES; PUNA VOLCANIC COMPLEX; LOCAL EARTHQUAKE DATA; ALTIPLANO-PUNA; UPPER MANTLE; STRUCTURE BENEATH; SUBDUCTION ZONES; NORTHERN CHILE; SEISMIC-WAVES; LOMA-PRIETA;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
85
Recensione:
Indirizzi per estratti:
Indirizzo: Haberland, C Geoforschungszentrum Potsdam, Sect 2 4, Telegrafenberg E252, D-14473 Potsdam, Germany Geoforschungszentrum Potsdam Telegrafenberg E252 Potsdam Germany D-14473
Citazione:
C. Haberland e A. Rietbrock, "Attenuation tomography in the western central Andes: A detailed insight into the structure of a magmatic arc", J GEO R-SOL, 106(B6), 2001, pp. 11151-11167

Abstract

High-quality data from 1498 local earthquakes recorded by the PISCO '94 (Proyecto de Investigacion Sismologica de la Cordillera Qccidental, 1994) andANCORP '96 (Andean Continental Research Project, 1996) temporary seismological networks allowed the detailed determination of the three-dimensional (3-D) attenuation structure (Q(p)(-1)) beneath the recent magmatic are in the western central Andes (200 to 24 degreesS). Assuming a frequency-independent Q(p)(-1) in a frequency band between 1 and 30 Hz, whole path attenuation (t*) was estimated from the amplitude spectra of the P waves using spectral ratios and a spectral inversion technique. The damped least squares inversion (tomography) of the data reveals a complex attenuation structure. Crust and mantle of the forearc and subducting slab are generally characterized by low attenuation (Q(p) > 1000). Crust and mantle beneath the magmatic are show elevated attenuation. The strongest anomaly of extremely low Q(p) is found in the crust between 22 degrees and 23 degreesS beneath the recent volcanic are (Q(p) < 100). N-S variations can be observed: The western flank of the crustal attenuation anomaly follows the curved course of the volcanic front. North of 21<degrees>S the attenuation is less developed. In the northern part of the study area the low-Q(p) zone penetrates in the forearcmantle down to the subducting slab. In the south a deeper zone of high attenuation is resolved between 23 degrees and 24 degreesS directly above the subducting slab. Low Q(p) in the mantle correlates with earthquake clusters. The strong crustal attenuation is confined to the distribution of young ignimbrites and silicic volcanism and is interpreted as a thermally weakenedzone with partial melts. The attenuation pattern in the upper mantle mightreflect the variable extent; of the asthenosphere and maps variations of subduction-related hydration processes in the mantle wedge from slab-derivedfluids.

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Documento generato il 28/03/20 alle ore 10:47:41