Earth and Planetary Science Letters
2018
rapid coastal uplift MIS 3 earthquake geology radiocarbon northern Chile megathrust earthquakes
Over long-term geological scales, the position and vertical movements of the coast are considered to be among the most important effects resulting from first-order plate tectonics interactions in the subduction zones. However, the relationship between short-term vertical deformation driven by earthquakes and long-term coastal uplift in the Andean subduction contact of northern Chile has not been thoroughly elucidated to date. Based on precise radiocarbon dating and geomorphological analysis of littoral deposits in the Mejillones Peninsula at the southern edge of the major northern Chile seismic gap, we report a drastic increase in coastal uplift since marine isotope stage 3 (MIS 3) with uplift rates one order of magnitude more rapid than previously in the Late Pleistocene. Geomorphological evidence supplied by Holocene littoral deposits and marine terraces shows that this tectonic regime could be operating at present. Together with new geodetic data following the 2007 Mw 7.7 Tocopilla event, these observations indicate that coastal uplift results from cumulative coseismic vertical displacement with low subsequent interseismic subsidence recovery driven by both deep-moderate and large megathrust earthquakes. We suggest that the accelerated coastal uprising and earthquake rate over the past ∼44 ka demonstrated in this work results from changes involving the entire subduction contact between the Nazca and South American plates in northern Chile.
José González-Alfaro a,∗; Gabriel Vargas a; Luc Ortlieb b,1; Gabriel González c; Sergio Ruiz d; Juan C. Báez e; Magloire Mandeng-Yogo b; Sandrine Caquineau b, Gabriel Álvarez f; Francisco del Campo e; Ian del Río c
a Departamento de Geología, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Plaza Ercilla 803, Santiago, Chile
b LOCEAN, IRD, Sorbonne Universités, (CNRS, MNHN, IRD France-Nord), Bondy, France
c Departamento de Ciencias Geológicas, Centro Nacional de Investigación para la Gestion Integrada de Desastres Naturales (Cigiden), Universidad Católica del Norte, Avenida Angamos 0610, Antofagasta, Chile
d Departamento de Geofísica, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Blanco Encalada 2002, Santiago, Chile
e Centro Sismológico Nacional, Universidad de Chile, Blanco Encalada 2002, Santiago, Chile
f Departamento de Ingeniería en Geomensura y Geomática, Facultad de Ingeniería, Universidad de Antofagasta, Avenida Universidad de Antofagasta 02800, Antofagasta, Chile