Segmentation of the 2010 Maule Chile earthquake rupture from a joint analysis of uplifted marine terraces and seismic-cycle deformation patterns. (1st April 2015)

• Record Type: Journal Article
• Authors: Jara-Muñoz, Julius; Melnick, Daniel; Brill, Dominik; Strecker, Manfred R.
• Is Part Of: Quaternary science reviews. Volume 113(2015)
• Page Start: 171
• Page End: 192
• Publication Date: 2015-04-01
• Subjects: LiDAR -- Subduction earthquakes -- Marine terraces -- Seismotectonic segmentation -- Permanent uplift -- Maule earthquake -- Coastal uplift -- TerraceM; Geology, Stratigraphic -- Quaternary -- Periodicals; Stratigraphie -- Quaternaire -- Périodiques; 551.79
• DOI: 10.1016/j.quascirev.2015.01.005
• Languages: English
• ISSNs: 0277-3791

Abstract

Abstract: The segmentation of major fault systems in subduction zones controls earthquake magnitude and location, but the causes for the existence of segment boundaries and the relationships between long-term deformation and the extent of earthquake rupture, are poorly understood. We compare permanent and seismic-cycle deformation patterns along the rupture zone of the 2010 Maule earthquake (M8.8), which ruptured 500 km of the Chile subduction margin. We analyzed the morphology of MIS-5 marine terraces using LiDAR topography and established their chronology and coeval origin with twelve luminescence ages, stratigraphy and geomorphic correlation, obtaining a virtually continuous distribution of uplift rates along the entire rupture zone. The mean uplift rate for these terraces is 0.5 m/ka. This value is exceeded in three areas, which have experienced rapid emergence of up to 1.6 m/ka; they are located at the northern, central, and southern sectors of the rupture zone, referred to as Topocalma, Carranza and Arauco, respectively. The three sectors correlate with boundaries of eight great earthquakes dating back to 1730. The Topocalma and Arauco sectors, located at the boundaries of the 2010 rupture, consist of broad zones of crustal warping with wavelengths of 60 and 90 km, respectively. These two regions coincide with the axes of oroclinal bending of the entire Andean margin and correlate with changes in curvature of the plate interface. Rapid uplift at Carranza, in turn, is of shorter wavelength and associated with footwall flexure of three crustal-scale normal faults. The uplift rate at Carranza is inversely correlated with plate coupling as well as with coseismic slip, suggesting permanent deformation may accumulate interseismically. We propose that the zones of upwarping at Arauco and Topocalma reflect changes in frictional properties of the megathrust resulting in barriers to the propagation of great earthquakes. Slip during the 1960 (M9.5) and 2010 events overlapped with the ∼90-km-long zone of rapid uplift at Arauco; similarly, slip in 2010 and 1906 extended across the ∼60-km-long section of the megathrust at Topocalma, but this area was completely breached by the 1730 (M∼9) event, which propagated southward until Carranza. Both Arauco and Topocalma show evidence of sustained rapid uplift since at least the middle Pleistocene. These two sectors might thus constitute discrete seismotectonic boundaries restraining most, but not all great earthquake ruptures. Based on our observations, such barriers might be breached during multi-segment super-cycle events. Highlights: Quantification of permanent uplift rates along the 2010 Maule Chile earthquake rupture. Marine terraces of MIS 5 correlated with luminescence ages and LiDAR topography. Long-wavelength antiformal structures form at the boundaries of the rupture. Rapidly-uplifting regions overlap with boundaries of M8-9.5 historical earthquakes.