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Sladen A.,California Institute of Technology | Tavera H.,Instituto Geofisico del Peru | Simons M.,California Institute of Technology | Avouac J.P.,California Institute of Technology | And 6 more authors.
Journal of Geophysical Research: Solid Earth | Year: 2010

We use Interferometric Synthetic Aperture Radar, teleseismic body waves, tsunami waveforms recorded by tsunameters, field observations of coastal uplift, subsidence, and runup to develop and test a refined model of the spatiotemporal history of slip during the Mw 8.0 Pisco earthquake of 15 August 2007. Our preferred solution shows two distinct patches of high slip. One patch is located near the epicenter while another larger patch ruptured 60 km further south, at the latitude of the Paracas peninsula. Slip on the second patch started 60 s after slip initiated on the first patch. We observed a remarkable anticorrelation between the coseismic slip distribution and the aftershock distribution determined from the Peruvian seismic network. The proposed source model is compatible with regional runup measurements and open ocean tsunami records. From the latter data set, we identified the 12 min timing error of the tsunami forecast system as being due to a mislocation of the source, caused by the use of only one tsunameter located in a nonoptimal azimuth. The comparison of our source model with the tsunami observations validate that the rupture did not extend to the trench and confirms that the Pisco event is not a tsunami earthquake despite its low apparent rupture velocity (<1.5 km/s). We favor the interpretation that the earthquake consists of two subevents, each with a conventional rupture velocity (2-4 km/s). The delay between the two subevents might reflect the time for the second shock to nucleate or, alternatively, the time it took for afterslip to increase the stress level on the second asperity to a level necessary for static triggering. The source model predicts uplift offshore and subsidence on land with the pivot line following closely the coastline. This pattern is consistent with our observation of very small vertical displacement along the shoreline when we visited the epicentral area in the days following the event. This earthquake represents, to our knowledge, one of the best examples of a link between the geomorphology of the coastline and the pattern of surface deformation induced by large interplate ruptures. Copyright 2010 by the American Geophysical Union. Source


Tejada-Lara J.V.,National Major San Marcos University | Tejada-Lara J.V.,Instituto Frances Of Estudios Andinos | Tejada-Lara J.V.,University of Florida | Salas-Gismondi R.,National Major San Marcos University | And 9 more authors.
Palaeontology | Year: 2015

The Middle Miocene has been identified as a time of great diversification in modern lineages now distributed in tropical South America, and when basic archetypal traits defining Amazonia appear, including climatic humid conditions, basic floral physiognomy and phylogenetic composition of modern rainforests. Nonetheless, Middle Miocene localities in South America are poorly known, especially at low latitudes where only one species-rich locality, La Venta in Colombia, has been extensively studied. The present contribution describes the mammal fauna of Fitzcarrald, a new Middle Miocene local fauna from western Amazonia in Peru. Fitzcarrald is correlated with the Laventan South American Land Mammal Age based on the presence of taxa defining the 'Miocochilius assemblage zone' in La Venta. The mammalian fauna of Fitzcarrald comprises 24 taxa among cingulates, folivores, astrapotheres, notoungulates, litopterns, rodents, odontocetes and a possible marsupial. At this time, tropical South America was characterized by the presence of the Pebas megawetland, a huge lacustrine complex that provided unique ecological and environmental conditions most likely isolating northern South America from southern South America. These isolating conditions might have come to an end with its disappearance in the Late Miocene and the establishment of the subsequent Acre system, the predecessor fluvial system of modern Amazonia. Results of faunistic similarity between Fitzcarrald and other Miocene faunas throughout South America support these scenarios. The Fitzcarrald mammal fauna exhibits first appearance datums and last appearance datums of various taxa, showing that tropical South America has played a crucial role in the evolutionary history and biogeography of major clades, and revealing a more complex biological history than previously proposed, based on the record from the southern cone of the continent. © The Palaeontological Association. Source


Cerdeno E.,CONICET | Vera B.,CONICET | Schmidt G.I.,CONICET | Pujos F.,CONICET | And 2 more authors.
Journal of Systematic Palaeontology | Year: 2012

A partial mesotheriine skeleton (Notoungulata, Mesotheriidae) from the Late Miocene Casira locality, southern Bolivia, is fully described and reinterpreted taxonomically. This specimen (MNHN-Bol-V-003724) was partially described previously without a taxonomic discussion, as it was considered to be Plesiotypotherium sp. After comparison with other Bolivian, Argentinean and Chilean mesotheres, we recognize a new species of the genus Plesiotypotherium Villarroel, P. casirense sp. nov., characterized by: nasals slightly enlarged posteriorly; zygomatic arch with strong antero-distal angle; zygomatic plate starting at the level of P4 and reaching the level of the anterior part of M3; lacrimal bony process; large infraorbital foramen; posterior border of the mandible very convex; P4 without lingual groove and with narrow and projected parastyle; M3 with simple third lobe; larger and more robust skeleton than other Plesiotypotherium species. Most postcranial elements are described in detail for the first time for Plesiotypotherium. The incomplete skull GB-KKL 740 from the same locality is also referred to the new taxon. P. casirense is the sister group of P. achirense Villarroel in the phylogenetic analysis, but the genus Plesiotypotherium appears as paraphyletic. The revised partial skull GB-ACH 100 from Achiri, Bolivia, which was labelled as Plesiotypotherium sp., does not belong to this genus, and it appears phylogenetically closer to Pseudotypotherium and Mesotherium. Plesiotypotherium casirense sp. nov. increases the known diversity of the Mesotheriidae in both the Miocene of Bolivia and the South American faunal context. © 2012 The Natural History Museum. Source


Lavallee D.,Archeologie des Ameriques | Julien M.,Archeologie et science de lAntiquite | Bearez P.,French Natural History Museum | Bolanos A.,National Major San Marcos University | And 8 more authors.
Chungara | Year: 2011

Research works at Quebrada de los Burros evidenced an Archaic settlement on the littoral of Tacna (Peru). This campsite of fishermen and shell-gatherers (QLB) has been occupied during Early and Middle Holocene, between 10,000 and 6,000 BP. Broad horizontal excavations revealed six successive occupation levels, with living floor layouts, hearths, specialized activity areas and accumulations of food waste of marine origin mixed with bones of terrestrial fauna. As a whole, these remains indicate that, since the beginning, the inhabitants relied intensively on ocean resources but they also exploited the lomas. Lithic tools and bone instruments attest a sophisticated equipment for fishing, gathering and hunting. Two phases of occupation were characterized, the first during Early Holocene (ca. 10,000 to 7,000 BP), the second during Middle Holocene (ca. 7,000 to 6,000 BP). The analyses suggest, for the first phase, a succession of short occupations and possible contacts with high lands and, on the contrary, a more intensive occupation, nearly all the year round, for the second, during which raw lithic materials came from nearby areas. A close relation with Chilean sites Chinchorro is confirmed. Source


Cartelle C.,PUC Minas | De Iuliis G.,University of Toronto | De Iuliis G.,Royal Ontario Museum | Pujos F.,CONICET | Pujos F.,Instituto Frances Of Estudios Andinos
Comptes Rendus - Palevol | Year: 2015

Recent reports (Faure et al., 2014; Guérin and Faure, 2000, 2008) describe the existence, in intertropical Brazil, of a small ("dwarf") megatheriine sloth, Eremotherium laurillardi (Lund, 1842), and a giant-sized megatheriine, Eremotherium rusconii (Schaub, 1935). This view is in marked contrast to that advanced by Cartelle and De Iuliis (1995, 2006), who demonstrated the presence of a single Late Pleistocene giant Eremotherium species, for which the valid name is Eremotherium laurillardi (Lund, 1842), in intertropical Brazil and elsewhere in America. These authors dubbed this species the Panamerican giant ground sloth. The present contribution reviews the material discussed by Faure et al. (2014) and demonstrates that it belongs to a juvenile (as did the material from Guérin and Faure, 2000) of the Panamerican giant ground sloth (i.e., E. laurillardi sensu Cartelle and De Iuliis, 1995, 2006) and that there is no evidence of a dwarf megatheriine in the Late Pleistocene of intertropical Brazil. © 2014 Académie des sciences. Source

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