The 27 February 2010 Chilean earthquake generated a large transpacific tsunami and controversy as to what some have referred to as overly conservative warning issued for Hawaii and Japan. We propose to conduct a rapid reconnaissance survey of the coastline of Chile and offshore islands of Santa Maria, Juan Fernandez and Easter, and the Marquesas in French Polynesia. The survey will interview eyewitnesses to determine the local tsunami kinematics, i.e., polarity of the first arrival, interval between waves and which wave in the train was the largest- and the societal response. The team will measure inundation distances and runup heights and will attempt to identify why the tsunami-related death toll in Chile is concentrated in a few specific locales. The questions that will be addressed include whether certain areas were tsunami traps and whether the observed runup height distribution around the Pacific was predictable, using existing numerical methods and forecast technology. The team will survey in the period between March 6 and March 24, since tsunami watermarks are highly ephemeral, and will coordinate closely with UNESCO, international and Chilean colleagues and their students.
This award is co-funded by the NSF Office of International Science and Engineering (OISE).
On February 27, 2010, a magnitude Mw = 8.8 earthquake occurred off the coast of Chile’s Maule region causing substantial damage and loss of life. As with most near-field tsunamis, the waves struck prior to official warnings reaching coastal residents. Self-evacuations minimized the fatalities and demonstrated the pivotal importance of community-based education and awareness programs [Synolakis and Bernard, 2006]. Ancestral tsunami knowledge from the 1960 event combined with education and evacuation exercises prompted most coastal residents to spontaneously evacuate after the earthquake. This partial success was overshadowed by the vast majority of tsunami victims being campers and tourists, a population that is not easily reached by community-based education. The international tsunami survey team (ITST) was deployed within days of the event and surveyed 800 km of coastline from Quintero to Mehuín and the Pacific Islands of Santa María, Mocha, Juan Fernández Archipelago, and Rapa Nui (Easter). The collected survey data include more than 400 tsunami flow depth, runup and coastal uplift measurements [Fritz et al., 2011]. The tsunami peaked with a localized runup of 29 m on a coastal bluff at Constitución. The observed runup distributions exhibit significant variations on local and regional scales. Despite small areas of locally high runup, the 2010 Chile tsunami had significantly lower sustained runup heights and a substantially smaller overall impact than either the 1960 Chile or the 2004 Indian Ocean tsunami. Intellectual Merit: The surveys took place using three integrated survey groups from March 7 to March 24, 2010 covering an 800 km stretch of South-Central Chilean coastline from Quintero to Mehuín, including Santa María Island in the Gulf of Arauco, Easter Island and Robinson Crusoe Island in the Juan Fernández Archipelago. A follow-up survey from May 21 to 23, 2010 focused on Mocha Island. Aerial reconnaissance flights were conducted between Pelluhue and the Arauco peninsula as well as over Robinson Crusoe and Mocha Islands. The survey teams documented tsunami runup, flow depth and inundation; wave induced deposition or erosion, structural damage and interviewed eyewitnesses using established protocols [Synolakis and Okal, 2005]. The Chile survey data recorded 419 tsunami runup and flow depth measurements shown in Figure 1 [Fritz et al., 2011]. This complex tsunami with large co-seismic coastal land-level changes prior to tsunami arrival and trans-Pacific impact on many Pacific Islands and flooding in Japan a day later was numerically modeled. The 2010 Chile earthquake represented a unique opportunity to characterize the co-seismic seafloor displacements because the Arauco peninsula and both Santa María and Mocha Islands are in proximity of the rupture. Coastal uplift was measured on uplifted intertidal rocks, as well as on navigation and port infrastructure using high tide water lines and eyewitness accounts along a 100 km stretch of coastline between Tumbes and Punta Morguilla. In the course of a few minutes, the Arauco Peninsula and Santa María Island acquired significant new land, mostly uplifted rocks and wide beaches.The coastal uplift during the earthquake prior to tsunami arrival locally reduced the tsunami impact, but severely affects navigation at several fishing ports. This data compliments localized high-precision GPS measurements. Broader Impact: The field data set has already become a benchmark for field work and validation of the combination of earthquake, tsunami and runup models. The complete database has become (part of) the official data base for the event (Government of Chile, UNESCO, and NGDC). Post tsunami field survey experience provided to local and international graduate students and senior scientists. More than half the participants trained were local Chilean academics and grad-students. This represents true capacity building in one of the world's most tsunami prone countries. Using the opportunity of working with field data, a few of the participants were trained in tsunami numerical tsunami simulations using MOST. The survey team did numerous outreach presentations to tsunami survivors, coastal communities, government agencies, universities during the Chile surveys and Viña del Mar AGU Chapman conference on the 1960 and 2010 Chile tsunamis. This included an Elementary School plenary audience presentation at the School in Rapa Nui (Easter Island). We met with SHOA (Chilean Navy) and ONEMI (Emergency Management) officials in charge of tsunami warnings and evacuations. Several news articles in the printed and online media including Chile's main newspapers. Prime time live interviews and documentaries on international and national radio and tv broadcasts. We have raised the tsunami awareness and we educated communities at risk about tsunamis and tsunami hazard mitigation.
