From the seismic cycle to long-term deformation: linking seismic coupling and Quaternary coastal geomorphology along the Andean megathrust

Abstract

Measurement of interseismic strain along subduction zones reveals the location of both locked asperities, which might rupture during megathrust earthquakes, and creeping zones, which tend to arrest such seismic ruptures. The heterogeneous pattern of interseismic coupling presumably relates to spatial variations of frictional properties along the subduction interface and may also show up in the fore‐arc morphology. To investigate this hypothesis, we compiled information on the extent of earthquake ruptures for the last 500 years and uplift rates derived from dated marine terraces along the South American coastline from central Peru to southern Chile. We additionally calculated a new interseismic coupling model for that same area based on a compilation of GPS data. We show that the coastline geometry, characterized by the distance between the coast and the trench; the latitudinal variations of long‐term uplift rates; and the spatial pattern of interseismic coupling are correlated. Zones of faster and long‐term permanent coastal uplift, evidenced by uplifted marine terraces, coincide with peninsulas and also with areas of creep on the megathrust where slip is mostly aseismic and tend to arrest seismic ruptures. We conclude that spatial variations of frictional properties along the megathrust dictate the tectono‐geomorphological evolution of the coastal zone and the extent of seismic ruptures along strike.

Tectonic Regimes of the Central and Southern Andes: Responses to Variations in Plate Coupling During Subduction

“…Over geological time frames (>10 5 years), the intensity of plate coupling determines whether the overriding continental plate undergoes long‐term shortening, extension, or quiescence. The time frame is crucial because the concept of plate coupling over millions of years, although similar in principle, is distinct from the many neotectonic and geodetic studies emphasizing seismic coupling on the subduction interface in relation to short‐term deformation on the scale of the subduction seismic cycle (<10 4 years) (e.g., Béjar‐Pizarro et al, ; Bevis et al, ; Saillard et al, ).…”

Tsunamigenic Splay Faults Imply a Long‐Term Asperity in Southern Prince William Sound, Alaska

“…Surface ruptures during subduction zone earthquakes can highlight patterns of coseismic motion (e.g., Fujiwara et al, 2011;Henstock et al, 2006), paleoseismic and geodetic observations can provide estimates of recurrence intervals and patterns of uplift/subsidence (e.g., Atwater & Hemphill-Haley, 1997;Cisternas et al, 2005;Saillard et al, 2017;Shennan et al, 2014;Sieh et al, 2008), and thermochronology measurements can provide regional uplift rates over thousands of earthquake cycles (e.g., Enkelmann et al, 2015;Ferguson et al, 2015;Haeussler et al, 2015). Surface ruptures during subduction zone earthquakes can highlight patterns of coseismic motion (e.g., Fujiwara et al, 2011;Henstock et al, 2006), paleoseismic and geodetic observations can provide estimates of recurrence intervals and patterns of uplift/subsidence (e.g., Atwater & Hemphill-Haley, 1997;Cisternas et al, 2005;Saillard et al, 2017;Shennan et al, 2014;Sieh et al, 2008), and thermochronology measurements can provide regional uplift rates over thousands of earthquake cycles (e.g., Enkelmann et al, 2015;Ferguson et al, 2015;Haeussler et al, 2015).…”

Roughness Characteristics of Oceanic Seafloor Prior to Subduction in Relation to the Seismogenic Potential of Subduction Zones

“…Soon after, Cloos () proposed that subducting seamounts were likely candidates for large earthquake triggers. Based on additional marine observations and physical modeling, alternative processes have been proposed involving multiple seismogenic behaviors depending on the type of subducting topographic features (Abercrombie et al, ; Bassett & Watts, , ; Bilek, ; Bilek et al, ; Carena, ; Cloos, ; Das & Watts, ; Dominguez et al, ; Geersen et al, ; Gutscher et al, ; Henstock et al, ; Kodaira et al, ; Konca et al, ; Kopp, ; Landgrebe & Müller, ; Marcaillou et al, ; Métois et al, ; Mochizuki et al, ; Morgan et al, ; Müller & Landgrebe, ; Robinson et al, ; Scholz & Small, ; Sparkes et al, ; Wang & Bilek, , ; Yang et al, ), the trench sediment thickness (Heuret et al, ; Jarrard, ; Ruff, ; Scholl et al, ), the state of stress within the upper plate (Heuret et al, ; Jarrard, ; Schellart & Rawlinson, ), the possible occurrence of tectonic erosion (Bilek, ; Sage et al, ; Scholl et al, ), the friction, normal stress, and fluid pressure along the subduction interface (Chlieh et al, ; Corbi et al, ; Lin et al, ; Ranero et al, ; Ruff, ; Saffer & Tobin, ; Saillard et al, ; Scholz, ) or the geometry or kinematics of the subduction zone (Bletery et al, ; Gutscher & Westbrook, ; Jarrard, ; McCaffrey, ; Schellart & Rawlinson, ; Uyeda, ). Some of these studies argue that along‐trench segments exhibiting low topographic roughness at long spatial wavelength should be prone to propagate ruptures over large distances and, consequently, be the location of very large earthquakes.…”