Abstract
On the 21st of April 2007, the Aysén Fjord earthquake (Mw 6.2) in southern Chile (45.3° S, 73.0° W) triggered hundreds of landslides in the epicentral area along the fjord coast and surroundings. Some of these landslides induced large tsunami waves within the fjord causing fatalities and damaging several salmon farms, the most important economic activity of the area. The landslides included rock slides and avalanches, rock falls, shallow soil and soil–rock slides, and debris flows. The earthquake was the climax of a seismic swarm that began 3 months earlier. The seismicity is associated with tectonic activity along the Liquiñe–Ofqui fault zone (LOFZ), a major structural feature of the region. The earthquake-induced landslides were mapped and classified from field observations and remote sensing analysis. The landslide areas and epicentral distances are within the expected range for the earthquake magnitude according to worldwide data, while the position of landslides on the slopes strongly suggests topographic amplification effects in triggering the failures. The location of the landslides is also clearly related to some of the main fault branches of the LOFZ. The seismic event has configured a new situation of seismic and landslide hazard in the Aysén region and along the LOFZ, where the presence of towns and economic infrastructure along the coasts of several fjords constitutes a potential risk that was not considered before this seismic event.
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Acknowledgments
This study was funded by Fondecyt Project 11070107, the Millenium Nucleus Montessus de Ballore International Earthquake Research Center, and the Energía Austral Limitada electricity company. Field work collaboration and support by G. Orozco, R. Rauld, F. Bondoux, the National Forestry Corporation, the National Emergency Office, and the Chilean Air Force are greatly acknowledged. We also thank Energía Austral for allowing publication of data obtained from baseline studies in the Cuervo River basin, as well as M. Arenas, R. Hermanns, S. Löw, I. Henderson, E. Anda, S. Saetre, P. Derch, G. Vargas, and L. Lara for their fruitful discussions in the field, S. Barrientos for his helpful insights on seismological issues, C. Padilla for helping with the database, and J. Le Roux and B. Townley for their review of the draft manuscript.
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Sepúlveda, S.A., Serey, A., Lara, M. et al. Landslides induced by the April 2007 Aysén Fjord earthquake, Chilean Patagonia. Landslides 7, 483–492 (2010). https://doi.org/10.1007/s10346-010-0203-2
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DOI: https://doi.org/10.1007/s10346-010-0203-2