TY - JOUR A1 - Vargas, Gabriel A1 - Farias, Marcelo A1 - Carretier, Sebastien A1 - Tassara, Andres A1 - Baize, Stephane A1 - Melnick, Daniel T1 - Coastal uplift and tsunami effects associated to the 2010 M(w)8.8 Maule earthquake in Central Chile JF - Andean geology N2 - On February 27, 2010 at 03:34:08 AM an M(w)8.8 earthquake, with epicenter located off Cobquecura (73.24 degrees W; 36.29 degrees S), severely hit Central Chile. The tsunami waves that followed this event affected the coastal regions between the cities of Valparaiso and Valdivia, with minor effects as far as Coquimbo. The earthquake occurred 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 degrees S and 38.34 degrees S, suggesting the latitudinal distribution of the earthquake rupture. The measured coastal uplift values varied between 240 +/- 20 cm at sites closer to the trench along the western coast of the Arauco peninsula and 15 +/- 10 cm at sites located farther east. A maximum value of 260 +/- 50 cm was observed at the western coast of Santa Maria Island, which is similar to the reported uplift associated with the 1835 earthquake at Concepcion. 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 ea. 14 m in the coastal area of the Maule Region immediately north of the epicenter, and diminished progressively northwards to 4-2 m near Valparaiso. 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 Tirua-Puerto Saavedra, in the Biobio 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 Biobio and Arauco regions. The tsunami effects were highly variable along the coast, as a result of geomorphological and bathymetric local conditions, besides potential complexities induced by the main shock. KW - M(w)8.8 Maule earthquake KW - Central Chile KW - Coseismic coastal uplift KW - Tsunami effect Y1 - 2011 U6 - https://doi.org/10.5027/andgeoV38n1-a12 SN - 0718-7106 VL - 38 IS - 1 SP - 219 EP - 238 PB - Servicio Nacional de Geologìa y Minerìa CY - Santiago ER - TY - JOUR A1 - Tolorza, Violeta A1 - Mohr, Christian Heinrich A1 - Carretier, Sebastien A1 - Serey, Amador A1 - Sepulveda, Sergio A. A1 - Tapia, Joseline A1 - Pinto, Luisa T1 - Suspended sediments in chilean rivers reveal low postseismic erosion after the maule earthquake (Mw 8.8) during a severe drought JF - Journal of geophysical research : Earth surface N2 - We address the question of whether all large-magnitude earthquakes produce an erosion peak in the subaerial components of fluvial catchments. We evaluate the sediment flux response to the Maule earthquake in the Chilean Andes (Mw 8.8) using daily suspended sediment records from 31 river gauges. The catchments cover drainage areas of 350 to around 10,000 km(2), including a wide range of topographic slopes and vegetation cover of the Andean western flank. We compare the 3- to 8-year postseismic record of sediment flux to each of the following preseismic periods: (1) all preseismic data, (2) a 3-year period prior to the seismic event, and (3) the driest preseismic periods, as drought conditions prevailed in the postseismic period. Following the earthquake, no increases in suspended sediment flux were observed for moderate to high percentiles of the streamflow distribution (mean, median, and >= 75th percentile). However, more than half of the examined stations showed increased sediment flux during baseflow. By using a Random Forest approach, we evaluate the contributions of seismic intensities, peak ground accelerations, co-seismic landslides, hydroclimatic conditions, topography, lithology, and land cover to explain the observed changes in suspended sediment concentration and fluxes. We find that the best predictors are hillslope gradient, low-vegetation cover, and changes in streamflow discharge. This finding suggests a combined first-order control of topography, land cover, and hydrology on the catchment-wide erosion response. We infer a reduced sediment connectivity due to the postseismic drought, which increased the residence time of sediment detached and remobilized following the Maule earthquake. KW - earthquake KW - suspended sediment KW - Maule megathrust KW - Chile KW - catchment Y1 - 2019 U6 - https://doi.org/10.1029/2018JF004766 SN - 2169-9003 SN - 2169-9011 VL - 124 IS - 6 SP - 1378 EP - 1397 PB - American Geophysical Union CY - Washington ER -