Segmentation in continental forearcs: Links between large-scale overriding plate structure and seismogenic behavior associated with the 2010 M  8.8 Maule, Chile earthquake

Bishop, Brandon T.; Beck, S. L.; Zandt, G.

doi:10.1016/j.tecto.2019.228164

Cited by 8 publications

(9 citation statements)

References 69 publications

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“…The average depth of the peaks at the six stations showing the Moho signal is about 34 km (Figure 2b, green). Bishop et al (2019) had two other profiles located much farther south, and the one shown in Figure 2b is the nearest to our main profile (Figure 1). In transferring their results to Figure 2b (red), we do not follow the original publication to extrapolate the Moho beyond the westernmost station showing the Moho signal (at ~38 km depth), located at roughly 140 km distance in Figure 3a of Bishop et al (2019).…”

Section: Moho Depthmentioning

confidence: 66%

“…Bishop et al (2019) had two other profiles located much farther south, and the one shown in Figure 2b is the nearest to our main profile (Figure 1). In transferring their results to Figure 2b (red), we do not follow the original publication to extrapolate the Moho beyond the westernmost station showing the Moho signal (at ~38 km depth), located at roughly 140 km distance in Figure 3a of Bishop et al (2019). In accordance with the two RF studies and taking into consideration their uncertainties, we assume the Moho to be in a depth range of 32-40 km (Figure 2b).…”

Section: Moho Depthmentioning

confidence: 66%

“…The downdip changes in Maule rupture stress drop, aftershock distribution, and possibly the radiation of seismic energy appear to correlate with the MWC. Figure 2b shows the continental Moho near the MWC based on the receiver function (RF) analyses of Dannowski et al (2013) and Bishop et al (2019). In Figure 3 of Dannowski et al (2013), the estimated Moho was drawn about one fourth wavelength below the peaks of the RF waveforms, but here we follow the common practice in RF analysis to use the peaks themselves to define the Moho.…”

Section: Role Of the Mantle Wedgementioning

confidence: 99%

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Role of Serpentinized Mantle Wedge in Affecting Megathrust Seismogenic Behavior in the Area of the 2010 M = 8.8 Maule Earthquake

Wang

Huang

Tilmann

et al. 2020

Geophysical Research Letters

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What controls subduction megathrust seismogenesis downdip of the mantle wedge corner (MWC)? We propose that, in the region of the 2010 M w = 8.8 Maule, Chile, earthquake, serpentine minerals derived from the base of the hydrated mantle wedge exert a dominant control. Based on modeling, we predict that the megathrust fault zone near the MWC contains abundant lizardite/chrysotile-rich serpentinite that transforms to antigorite-rich serpentinite at greater depths. From the MWC at 32-40 km depth to at least 55 km, the predominantly velocity-strengthening megathrust accommodated dynamic propagation of the 2010 rupture but with small slip and negative stress drop. The downdip distribution of interplate aftershocks exhibits a gap around the MWC that can be explained by the velocity-strengthening behavior of lizardite/chrysotile. Interspersed velocity-weakening and dynamic weakening antigorite-rich patches farther downdip may be responsible for increased abundance of aftershocks and possibly for some of the high-frequency energy radiation during the 2010 rupture. Plain Language Summary A subduction megathrust rupture may extend from the trench to beneath populated coastal area. To understand what controls the megathrust seismogenic behavior of its deeper part, we conduct a case study of the 2010 magnitude 8.8 Maule, Chile, earthquake and its aftershocks. With numerical thermal modeling, we find that the deep seisomogenic behavior may be controlled by serpentine materials derived from the base of the overlying hydrated mantle wedge. The deep part of the megathrust ruptured "passively" against increasing resistance (negative stress drop). Lower-temperature serpentines lizardite and chrysotile that are known to facilitate aseismic slip may be responsible for an observed gap in aftershock distribution in the downdip direction. Higher-temperature serpentine antigorite that is known to facilitate seismic slip may be responsible for increased aftershocks farther downdip and possibly radiation of high-frequency energy during the 2010 Maule earthquake. Hydrous minerals such as serpentine, talc, and chlorite form in the forearc mantle wedge with the addition of aqueous fluids from the subducting slab (Hyndman & Peacock, 2003; Reynard, 2013). In warm subduction ©2020. Her Majesty the Queen in Right of Canada. Reproduced with the permission of the Minister of Natural Resources Canada.

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Section: Moho Depthmentioning

confidence: 66%

Section: Moho Depthmentioning

confidence: 66%

Section: Role Of the Mantle Wedgementioning

confidence: 99%

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Role of Serpentinized Mantle Wedge in Affecting Megathrust Seismogenic Behavior in the Area of the 2010 M = 8.8 Maule Earthquake

Wang

Huang

Tilmann

et al. 2020

Geophysical Research Letters

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“…This layering may be the deep expression of the Western Series, a now-exhumed paleo-accretionary complex that was basally accreted in the late Paleozoic (Glodny et al, 2005;Willner, 2005). This interpretation is supported by tomographic images and receiver function analysis suggesting the existence of underplated metasediments between ~20 and 40 km depth at the base of the forearc crust (Haberland et al, 2009;Bishop et al, 2019). Alternatively, the northern Chilean erosive margin does not exhibit clear geophysical imaging of underplated material (e.g., Oncken et al, 2003) despite indirect evidence (see the Surface Expression of Ongoing Basal Accretion section).…”

Section: Research Papermentioning

confidence: 79%

The rise and demise of deep accretionary wedges: A long-term field and numerical modeling perspective

2021

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Several decades of field, geophysical, analogue, and numerical modeling investigations have enabled documentation of the wide range of tectonic transport processes in accretionary wedges, which constitute some of the most dynamic plate boundary environments on Earth. Active convergent margins can exhibit basal accretion (via underplating) leading to the formation of variably thick duplex structures or tectonic erosion, the latter known to lead to the consumption of the previously accreted material and eventually the forearc continental crust. We herein review natural examples of actively underplating systems (with a focus on circum-Pacific settings) as well as field examples highlighting internal wedge dynamics recorded by fossil accretionary systems. Duplex formation in deep paleo–accretionary systems is known to leave in the rock record (1) diagnostic macro- and microscopic deformation patterns as well as (2) large-scale geochronological characteristics such as the downstepping of deformation and metamorphic ages. Zircon detrital ages have also proved to be a powerful approach to deciphering tectonic transport in ancient active margins. Yet, fundamental questions remain in order to understand the interplay of forces at the origin of mass transfer and crustal recycling in deep accretionary systems. We address these questions by presenting a suite of two-dimensional thermo-mechanical experiments that enable unravelling the mass-flow pathways and the long-term distribution of stresses along and above the subduction interface as well as investigating the importance of parameters such as fluids and slab roughness. These results suggest the dynamical instability of fluid-bearing accretionary systems causes either an episodic or a periodic character of subduction erosion and accretion processes as well as their topographic expression. The instability can be partly deciphered through metamorphic and strain records, thus explaining the relative scarcity of paleo–accretionary systems worldwide despite the tremendous amounts of material buried by the subduction process over time scales of tens or hundreds of millions of years. We finally stress that the understanding of the physical processes at the origin of underplating processes as well as the forearc topographic response paves the way for refining our vision of long-term plate-interface coupling as well as the rheological behavior of the seismogenic zone in active subduction settings.

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“…The map shows ocean-continent subduction zones around the Circum-Pacific region with emphasis on segments where tectonic underplating is suspected, based on geophysical observations. (1) Hikurangi margin [64][65][66] , (2) Nankai margin 67 , (3) Sagami trough 23 , (4) Alaska margin 68,69 , (5) Cascadia margin [70][71][72] , (6) Costa Rica margin 73 , (7) North Chilean margin 74,75 and (8) Central Chilean margin 74,[76][77][78][79] . Black frames locate regions where trench-perpendicular topographic profiles have been compiled.…”

mentioning

confidence: 99%

Transient stripping of subducting slabs controls periodic forearc uplift

et al. 2020

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Topography in forearc regions reflects tectonic processes along the subduction interface, from seismic cycle-related transients to long-term competition between accretion and erosion. Yet, no consensus exists about the topography drivers, especially as the contribution of deep accretion remains poorly constrained. Here, we use thermo-mechanical simulations to show that transient slab-top stripping events at the base of the forearc crust control upliftthen-subsidence sequences. This 100s-m-high topographic signal with a Myr-long periodicity, mostly inaccessible to geodetic and geomorphological records, reflects the nature and influx rate of material involved in the accretion process. The protracted succession of stripping events eventually results in the pulsing rise of a large, positive coastal topography. Trench-parallel alternation of forearc highs and depressions along active margins worldwide may reflect temporal snapshots of different stages of these surface oscillations, implying that the 3D shape of topography enables tracking deep accretion and associated plate-interface frictional properties in space and time.

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Segmentation in continental forearcs: Links between large-scale overriding plate structure and seismogenic behavior associated with the 2010 M 8.8 Maule, Chile earthquake

Cited by 8 publications

References 69 publications

Role of Serpentinized Mantle Wedge in Affecting Megathrust Seismogenic Behavior in the Area of the 2010 M = 8.8 Maule Earthquake

Role of Serpentinized Mantle Wedge in Affecting Megathrust Seismogenic Behavior in the Area of the 2010 M = 8.8 Maule Earthquake

The rise and demise of deep accretionary wedges: A long-term field and numerical modeling perspective

Transient stripping of subducting slabs controls periodic forearc uplift

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