%0 Journal Article
%T Coastal uplift and tsunami effects associated to the 2010 Mw8.8 Maule earthquake in Central Chile Levantamiento cos¨ªsmico e impacto del tsunami a lo largo de la costa de Chile central asociado al terremoto del Maule Mw8.8 de 2010
%A Gabriel Vargas
%A Marcelo Far¨ªas
%A S¨¦bastien Carretier
%A Andr¨¦s Tassara
%J Andean Geology
%D 2011
%I Servicio Nacional de Geolog¨ªa y Miner¨ªa (SERNAGEOMIN)
%X On February 27, 2010 at 03:34:08 AM an Mw8.8 earthquake, with epicenter located off Cobquecura (73.24¡ãW; 36.29¡ãS), severely hit Central Chile. The tsunami waves that followed this event affected the coastal regions between the cities of Valpara¨ªso and Valdivia, with minor effects as far as Coquimbo. The earthquake oceurred along the subduction of the Nazca oceanic plate beneath the South American plate. Coseismic coastal uplift was estimated through observations of bleached lithothamnioids crustose coralline algae, which were exposed after the mainshock between 34.13¡ãS and 38.34¡ãS, suggesting the latitudinal distribution of the earthquake rupture. The measured coastal uplift values varied between 240¡À20 cm at sites closerto the trench along the western coast of the Arauco peninsulaand 15¡À10 cm at sites located farther east. A maximum valu¨¦ of 260¡À50 cm was observed at the western coast of Santa Mar¨ªa Island, which is similar to the reported uplift associated with the 1835 earthquake at Concepci¨®n. Land subsidence values on the order of 0.5 m to 1 m evidenced a change in polarity and position of the coseismic hinge at 110-120 km from the trench. In four sites along the coast we observed a close match between coastal uplift values deduced from bleached lithothamnioids algae and GPS measurements. According to field observations tsunami heights reached ca. 14 m in the coastal area of the Maule region immediately north of the epicenter, and diminished progressively northwards to 4-2 m near Valpara¨ªso. Along the coast of Cobquecura, tsunami height values were inferior to 2-4 m. More variable tsunami heights of 6-8 m were measured at Dichato-Talcahuano and Tir¨²a-Puerto Saavedra, in the Biob¨ªo and Arauco regions, respectively, to the south of the epicenter. According to eyewitnesses, the tsunami reached the coast between 12 to 20 and 30 to 45 minutes in areas located closer and faraway from the earthquake rupture zone, respectively. Destructive tsunami waves arrived also between 2.5 and 4.5 hours after the mainshock, especially along the coast of the Biob¨ªo and Arauco regions. The tsunami effects were highly variable along the coast, as a result of geomorphological and bathy-metric local conditions, besides potential complexities induced by the main shock.
%K M 8.8 Maule earthquake
%K Central Chile
%K Coseismic coastal uplift
%K Tsunami effect
%K Terremoto M 8
%K 8
%K Chile central
%K Levantamiento cos¨ªsmico costero
%K Tsunami
%U http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-71062011000100011