Subducting seamounts control interplate coupling and seismic rupture in the 2014 Iquique earthquake area

Geersen, Jacob; Ranero, César R.; Barckhausen, Udo; Reichert, Christian

doi:10.1038/ncomms9267

Cited by 81 publications

(92 citation statements)

References 26 publications

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“…The rupture length and location for recent strong events were taken from Barrientos & Ward (1990) for the M9.6 1960 Valdivia earthquake, Delouis et al (1997) for the M7.6 1987 earthquake near Antofagasta, Ruegg et al (1996) for the M8.0 1995 Antofagasta earthquake, Pritchard & Simons (2006) for the M9.6 1960 Valdivia earthquake, Chlieh et al (2011) for the M8.4 2001 Arequipa earthquake, the rupture plane of which extends well into our area of investigation, Schurr et al (2014) for the M7.9 2007 Tocopilla earthquake, Yue et al (2014) for the M8.8 2010 Maule earthquake, Geersen et al (2015) and Schurr et al (2014) for the M8.1 2014 Iquique earthquake, and Tilmann et al (2016) for the M8.2 2015 Illapel earthquake. In the case that the rupture length is not constrained by observations, we estimate rupture lengths from the scaling relation of Blaser et al (2010) for dip-slip inter-plate earthquakes.…”

Section: Data Preparationsupporting

confidence: 59%

“…From 1900 to 2013 we use the ISC-GEM data (Storchak et al 2013). Later earthquakes are included by hand, that is, for the 2014 Iquique earthquake using Geersen et al (2015) and Schurr et al (2014) and for the 2015 Illapel earthquake using Tilmann et al (2016). We confine our study to earthquakes with intensity of 8 and higher or any magnitude value being equal or higher than 6.5.…”

Section: Data Preparationmentioning

confidence: 99%

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Testing stress shadowing effects at the South American subduction zone

Roth¹,

Dahm²,

Hainzl³

2017

Geophysical Journal International

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S U M M A R YThe seismic gap hypothesis assumes that a characteristic earthquake is followed by a long period with a reduced occurrence probability for the next large event on the same fault segment, as a consequence of the induced stress shadow. The gap model is commonly accepted by geologists and is often used for time-dependent seismic hazard estimations. However, systematic and rigorous tests to verify the seismic gap model have often failed so far, which might be partially related to limited data and too tight model assumptions. In this study, we relax the assumption of a characteristic size and location of repeating earthquakes and analyse one of the best available data sets, namely the historical record of major earthquakes along a 3000 km long linear segment of the South American subduction zone. To test whether a stress shadow effect is observable, we compiled a comprehensive catalogue of mega-thrust earthquakes along this plate boundary from 1520 to 2015 containing 174 earthquakes with M w > 6.5. In our new testing approach, we analyse the time span between an earthquake and the last event that ruptured the epicentre location, where we consider the impact of the uncertainties of epicentres and rupture extensions. Assuming uniform boundary conditions along the trench, we compare the distribution of these recurrence times with simple recurrence models. We find that the distribution is in all cases almost exponentially distributed corresponding to a random (Poissonian) process; despite some tendencies for clustering of the M w ≥ 7 events and a weak quasi-periodicity of the M w ≥ 8 earthquakes, respectively. To verify whether the absence of a clear stress shadow signal is related to physical assumptions or data uncertainties, we perform simulations of a physics-based stochastic earthquake model considering rate and state-dependent earthquake nucleation, which are adapted to the observations with regard to the number of events, spatial extend, size distribution and involved uncertainties. Our simulations show that the catalogue uncertainties lead to a significant blurring of the theoretically peaked distribution, but the distribution would be still distinguishable from the observed one for M w ≥ 7 events. However, considering the stress transfer to adjacent fault segments and heterogeneous instead of constant stress drop within the rupture zone can explain the observed recurrence time distribution. We conclude that simplified recurrence models, ignoring the complexity of the underlying physical process, cannot be applied for forecasting the M w ≥ 7 earthquake occurrence at this plate boundary.

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Section: Data Preparationsupporting

confidence: 59%

Section: Data Preparationmentioning

confidence: 99%

Testing stress shadowing effects at the South American subduction zone

Roth¹,

Dahm²,

Hainzl³

2017

Geophysical Journal International

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“…Wang & Bilek 2011;Geersen et al 2015). Around 32.3 • S, the subducting seamounts of the JFR, cause widespread (over tens of kilometres) fracturing around the initial plate boundary fault zone.…”

Section: R E S U Lt S a N D Discussionmentioning

confidence: 99%

Aftershock seismicity and tectonic setting of the 2015 September 16 Mw 8.3 Illapel earthquake, Central Chile

Lange

Geersen

Barrientos

et al. 2016

Geophysical Journal International

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Powerful subduction zone earthquakes rupture thousands of square kilometres along continental margins but at certain locations earthquake rupture terminates. To date, detailed knowledge of the parameters that govern seismic rupture and aftershocks is still incomplete. On 2015 September 16, the Mw 8.3 Illapel earthquake ruptured a 200 km long stretch of the Central Chilean subduction zone, triggering a tsunami and causing significant damage. Here, we analyse the temporal and spatial pattern of the coseismic rupture and aftershocks in relation to the tectonic setting in the earthquake area. Aftershocks cluster around the area of maximum coseismic slip, in particular in lateral and downdip direction. During the first 24 hr after the main shock, aftershocks migrated in both lateral directions with velocities of approximately 2.5 and 5 km hr−1. At the southern rupture boundary, aftershocks cluster around individual subducted seamounts that are related to the downthrusting Juan Fernández Ridge. In the northern part of the rupture area, aftershocks separate into an upper cluster (above 25 km depth) and a lower cluster (below 35 km depth). This dual seismic–aseismic transition in downdip direction is also observed in the interseismic period suggesting that it may represent a persistent feature for the Central Chilean subduction zone.

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“…For example, Kodaira et al (2000) imaged a subducted seamount at depth in the Nankai subduction zone that they suggest acted as a barrier in the 1946 M w 8.3 Nankai earthquake rupture. Other examples of significant subducted topography acting as rupture barriers include along the South American margin (e.g., Perfettini et al, 2010;Sparkes et al, 2010;Geersen et al, 2015), Sumatra margin (e.g., Chlieh et al, 2008;Henstock et al, 2016), and Japan Trench (e.g., Simons et al, 2011;Duan, 2012). In some cases, the subducting topography may initially act as a barrier and then fail later in the rupture, producing significant slip, as proposed for the 2001 M w 8.4 Peru earthquake (Robinson et al, 2006).…”

Section: Role Of Rough Downgoing Plate Topographymentioning

confidence: 99%

Subduction zone megathrust earthquakes

2018

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Subduction zone megathrust faults host Earth's largest earthquakes, along with multitudes of smaller events that contribute to plate convergence. An understanding of the faulting behavior of megathrusts is central to seismic and tsunami hazard assessment around subduction zone margins. Cumulative sliding displacement across each megathrust, which extends from the trench to the downdip transition to interplate ductile deformation, is accommodated by a combination of rapid stick-slip earthquakes, episodic slow-slip events, and quasi-static creep. Megathrust faults have heterogeneous frictional properties that contribute to earthquake diversity, which is considered here in terms of regional variations in maximum recorded magnitudes, Gutenberg-Richter b values, earthquake productivity, and cumulative seismic moment depth distributions for the major subduction zones. Great earthquakes on megathrusts occur in irregular cycles of interseismic strain accumulation, foreshock activity, main-shock rupture, postseismic slip, viscoelastic relaxation, and fault healing, with all stages now being captured by geophysical monitoring. Observations of depth-dependent radiation characteristics, large earthquake slip distributions, variations in rupture velocities, radiated energy and stress drop, and relationships to aftershock distributions and afterslip are discussed. Seismic sequences for very large events have some degree of regularity within subduction zone segments, but this can be complicated by supercycles of intermittent huge ruptures that traverse segment boundaries. Factors influencing variability of large megathrust ruptures, such as large-scale plate structure and kinematics, presence of sediments and fluids, lower-plate bathymetric roughness, and upper-plate structure, are discussed. The diversity of megathrust failure processes presents a suite of natural hazards, including earthquake shaking, submarine slumping, and tsunami generation. Improved monitoring of the offshore environment is needed to better quantify and mitigate the threats posed by megathrust earthquakes globally.

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Subducting seamounts control interplate coupling and seismic rupture in the 2014 Iquique earthquake area

Cited by 81 publications

References 26 publications

Testing stress shadowing effects at the South American subduction zone

Testing stress shadowing effects at the South American subduction zone

Aftershock seismicity and tectonic setting of the 2015 September 16 Mw 8.3 Illapel earthquake, Central Chile

Subduction zone megathrust earthquakes

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