%0 Journal Article
%T Morphologic description of the Punta Cola rock avalanche and associated minor rockslides caused by the 21 April 2007 Ays谷n earthquake (Patagonia, southern Chile) Descripci車n morfol車gica de la avalancha de rocas de Punta Cola y deslizamientos de rocas asociados causados por el terremoto de Ays谷n del 21 de abril de 2007 (Patagonia, sur de Chile)
%A Thierry Oppikofer
%A Reginald L Hermanns
%A Tim F Redfield
%A Sergio A Sep迆lveda
%J Revista de la Asociaci車n Geol車gica Argentina
%D 2012
%I Asociaci車n Geol車gica Argentina
%X The 21 April 2007 Ays谷n earthquake triggered hundreds of landslides in the epicentral area, including several large-volume rock avalanches that caused tsunamis in the Ays谷n fjord. This study is part of a larger project aiming to better understand the conditioning factors controlling size and distribution of earthquake-triggered landslides. The focus is set on the largest rockslide that occurred at Punta Cola. Using a high-resolution digital surface model created from terrestrial laser scanning, a detailed geomorphologic map of the rockslide scars and the rock avalanche deposits on land was made. This map permitted to establish the sequence of events: the failure of the rockslide main compartment led to a rock avalanche that crossed the valley and ran up on the opposite valley flank before turning downstream and impacting the fjord and creating a tsunami. Afterwards, another rockslide compartment failed and piled up 80 m thick deposits in the valley. Seven minor rockslides occurred in the Punta Cola valley after the main rock avalanche. The volumes of rockslides and associated deposits were estimated using the sloping local base level technique that allows computing the possible pre-rockslide topography and the bedrock-deposits interface. These volume computations give 22.4 Mm3 for the Punta Cola rockslide, which is significantly more than previous estimates (12 Mm3). The on-shore deposits of the main rock avalanche have a volume of 13.7 Mm3 and approximately 14.4 Mm3 are deposited in the fjord. This study highlights the additional information on rockslides and rock avalanches that can be obtained from high-resolution 3D data and mapping. El terremoto de Ays谷n del 21 de abril de 2007 gener車 cientos de remociones en masa en la zona epicentral, incluyendo varias avalanchas de roca de gran volumen que causaron tsunamis en el fiordo Ays谷n. Este estudio es parte de un proyecto orientado a una mejor comprensi車n de los factores que controlan el tama o y distribuci車n de remociones en masa generadas por sismos. El estudio se centra en el deslizamiento de mayor tama o, ocurrido en el sector de Punta Cola. Mediante el uso de un modelo de terreno digital de alta resoluci車n creado a partir de un escaneo l芍ser terrestre, se prepar車 un mapa geomorfol車gico de las zonas de arranque y dep車sitos de la avalancha de roca, el cual permite establecer la secuencia de eventos: la falla de la secci車n mayor de deslizamiento deriv車 a una avalancha de roca que cruz車 el valle trepando el flanco opuesto antes de girar hacia aguas abajo e impactar el fiordo generando un tsunami. Poster
%K Escaneo l芍ser terrestre
%K Modelo de elevaci車n digital
%K Zona de arranque
%K Dep車sitos
%K C芍lculo de volumen
%K Terrestrial laser scanning
%K Digital elevation model
%K Scar
%K Deposits
%K Volume computation
%U http://www.scielo.org.ar/scielo.php?script=sci_arttext&pid=S0004-48222012000300003