Deformation patterns associated with the seismic cycle of the 27 February Maule earthquake segment at various spatiotemporal scales
Final Report Abstract
Strain accumulation and release during the subduction-earthquake cycle governs the recurrence and magnitude of destructive earthquakes and associated tsunamis, such as the 2010 Maule event. Understanding the relation between long-term deformation patterns of forearcs, manifested in the geology and geomorphology, and co-seismic megathrust slip is of utmost importance for deciphering the mechanisms governing the earthquake process and assessments of seismic hazards. In this project we have obtained a detailed record of permanent deformation over several earthquake cycles along strike of the Maule rupture using marine terraces. The comparison of coseismic slip, interseismic coupling, and permanent deformation, leads to three areas of high permanent uplift, terrace warping, and sharp fault offsets. These three areas correlate with regions of high slip and low coupling, as well as with the spatial limit of at least eight historical megathrust ruptures (M8-9.5). We propose that the zones of upwarping at Arauco and Topocalma, at the limits of the rupture zone, reflect changes in frictional properties of the megathrust, which result in discrete boundaries for the propagation of mega earthquakes. During this project we identified different patterns of permanent deformation. For instance, long-wavelength structures are associated with deeper sources of deformation, such as those that occur at the megathrust zone. Instead, short-wavelength structures can be associated with local shallow sources of deformation, such as active structures in the upper plate. On the other hand, considering that the magnitude of permanent deformation along the Maule earthquake rupture correlates with the distance to the trench and the depth of the slab, we propose that the spatial distribution of permanent deformation and the geometry of the subduction system might be useful to infer in which phase of the seismic cycle permanent deformation was accrued. The results of this project provide novel and fundamental information regarding the earthquake cycle and beyond. Our results highlight where cumulative, permanent crustal deformation was accrued along the 2010 Maule earthquake (M8.8) rupture zone. Furthermore, the results of this project underscore the usefulness of the application of quantitative geomorphology in seismotectonic research and they emphasize the use of repeatable methods in determining permanent deformation features applying different marine terrace end-members, which significantly improves the accuracy of marine terrace assessments in tectonically active coastal areas. The methods developed to analyze terraces (marine and lacustrine) were made available online for the scientific community (www.terracem.com). To date, several colleagues from universities and research institutes are developing their research using the programmatic tool TerraceM.
Publications
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(2017) Quantifying offshore fore-arc deformation and splay-fault slip using drowned Pleistocene shorelines, Arauco Bay, Chile. J. Geophys. Res. Solid Earth (Journal of Geophysical Research: Solid Earth) 122 (6) 4529–4558
Jara-Muñoz, Julius; Melnick, Daniel; Zambrano, Patricio; Rietbrock, Andreas; González, Javiera; Argandoña, Boris; Strecker, Manfred R.
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Controls on submarine canyon activity during sea-level highstands: The Biobio canyon system offshore Chile. Geosphere 2015, 11(4): 1226-1255
Bernhardt A, Melnick D, Jara-Muñoz J, Argandoña B, González J, Strecker MR
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Segmentation of the 2010 Maule Chile earthquake rupture from a joint analysis of uplifted marine terraces and seismic-cycle deformation patterns. Quaternary Science Reviews 2015,113: 171-192
Jara-Munoz J, Melnick D, Brill D, Strecker MR
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Unraveling sea-level variations and tectonic uplift in wave-built marine terraces, Santa María Island, Chile. Quaternary Research 2015, 83(1): 216-228
Jara-Munoz J, Melnick D
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TerraceM: A MATLAB(R) tool to analyze marine and lacustrine terraces using high-resolution topography. Geosphere 2016, 12(1), 176-195
Jara-Muñoz J, Melnick D, Strecker MR
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2017, Slip along the Sultanhani Fault in Central Anatolia from deformed Pleistocene shorelines of palaeo-lake Konya and implications for seismic hazards in low-strain regions, Geophysical Journal International, v. 209, p. 1431-1454
Melnick, D., Yildirim, C., Hilemann, C., Garcin, Y., Çiner, A., Pérez-Gussinyé, M. & Strecker, M.R.
