Publicaciones

Upper plate reverse fault reactivation and the unclamping of the megathrust during the 2014 northern Chile earthquake sequence

Journal

Geology

Línea de investigación

Amenazas por procesos de tierra sólida

Institución

Universidad Católica del Norte, Pontificia Universidad Católica de Chile

Disciplina

Ciencias de la Tierra

afiliacion

  1. Gabriel González, National Research Center for Integrated Natural Disaster Management. Universidad Católica del Norte, Avenida Angamos 0610, Antofagasta, Chile
  2. Pablo Salazar, National Research Center for Integrated Natural Disaster Management. Universidad Católica del Norte, Avenida Angamos 0610, Antofagasta, Chile
  3. John P. Loveless, Department of Geosciences, Smith College, Northampton, Massachusetts 01063, USA
  4. Richard W. Allmendinger, Department of Earth and Atmospheric Sciences, Cornell University, Ithaca, New York 14853, USA
  5. Felipe Aron, Department of Geological Sciences, Stanford University, Stanford, California 94305, USA. Departamento de Ingeniería Estructural y Geotécnica, Pontificia Universidad Católica de Chile, Vicuña Mackenna 4860, Macul, Santiago, Chile
  6. Mahesh Shrivastava, National Research Center for Integrated Natural Disaster Management. Universidad Católica del Norte, Avenida Angamos 0610, Antofagasta, Chile

Abstract

After 137 years without a great earthquake, the Mw 8.1 Pisagua event of 1 April 2014 occurred in the central portion of the southern Peru–northern Chile subduction zone. This megathrust earthquake was preceded by more than 2 weeks of foreshock activity migrating ∼3.5 km/ day toward the mainshock hypocenter. This foreshock sequence was triggered by an Mw 6.7 earthquake on a reverse fault in the upper plate that strikes at a high angle to the trench, similar to well-documented reverse faults onshore. These margin-oblique reverse faults accommodate north-south shortening resulting from subduction across a plate boundary that is curved in map view. Reverse slip on the crustal fault unclamped the subduction interface, precipitating the subsequent megathrust foreshock activity that culminated in the great Pisagua earthquake. The combination of crustal reverse faults and a curved subduction margin also occurs in Cascadia and northeastern Japan, indicating that there are two additional localities where great megathrust earthquakes may be triggered by upper plate fault activity.

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