Postseismic relocking of the subduction megathrust following the 2007 Pisco, Peru, earthquake. Issue 5 (27th May 2016)

• Record Type: Journal Article
• Authors: Remy, D.; Perfettini, H.; Cotte, N.; Avouac, J. P.; Chlieh, M.; Bondoux, F.; Sladen, A.; Tavera, H.; Socquet, A.
• Is Part Of: Journal of geophysical research. Volume 121:Issue 5(2016:May)
• Page Start: 3978
• Page End: 3995
• Publication Date: 2016-05-27
• Subjects: GPS -- InSAR -- seismic cycle -- postseismic slip -- slip budget; Geomagnetism -- Periodicals; Geochemistry -- Periodicals; Geophysics -- Periodicals; Earth sciences -- Periodicals; 551.1
• DOI: 10.1002/2015JB012417
• Languages: English
• ISSNs: 2169-9313

Abstract

Abstract: Characterizing the time evolution of slip over different phases of the seismic cycle is crucial to a better understanding of the factors controlling the occurrence of large earthquakes. In this study, we take advantage of interferometric synthetic aperture radar data and 3.5 years of continuous Global Positioning System (GPS) measurements to determine interseismic, coseismic, and postseismic slip distributions in the region of the 2007, Mw 8.0 Pisco, earthquake, Peru, using the same fault geometry and inversion method. Our interseismic model, based on pre‐2007 campaign GPS data, suggests that the 2007 Pisco seismic slip occurred in a region strongly coupled before the earthquake while afterslip occurred in low coupled regions. Large afterslip occurred in the peripheral area of coseismic rupture in agreement with the notion that afterslip is mainly induced by coseismic stress changes. The temporal evolution of the region of maximum afterslip, characterized by a relaxation time of about 2.3 years, is located in the region where the Nazca ridge is subducting, consistent with rate‐strengthening friction promoting aseismic slip. We estimate a return period for the Pisco earthquake of about 230 years with an estimated aseismic slip that might account for about 50% of the slip budget in this region over the 0–50 km seismogenic depth range. A major result of this study is that the main asperity that ruptured during the 2007 Pisco earthquake relocked soon after this event. Key Points: Characterization of the time evolution of slip following the 2007 Pisco, Peru, earthquake Postseismic relocking of the subduction megathrust revealed by GPS and InSAR data Aseismic slip might account for about 50% of the slip budget in the region of Pisco