Rupture processes of the 2012 September 5<i>M</i><sub>w</sub>7.6 Nicoya, Costa Rica earthquake constrained by improved geodetic and seismological observations

Liu, Chengli; Zheng, Yong; Xiong, Xiong; Wang, Rongjiang; López, A. M.; Li, Jun

doi:10.1093/gji/ggv295

Cited by 14 publications

(9 citation statements)

References 32 publications

(40 reference statements)

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“…[] and Liu et al . [] models of coseismic rupture, suggesting that this is not highly dependent on the 3‐D nature of the model geometry used here. This elongate feature is not observed in the combined high‐rate GPS and seismic inversion model of Yue et al .…”

Section: Resultsmentioning

confidence: 83%

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Structural asperity focusing locking and earthquake slip along the Nicoya megathrust, Costa Rica

Kyriakopoulos

Newman

2016

JGR Solid Earth

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On 5 September 2012, a moment magnitude 7.6 earthquake occurred along the locked megathrust interface directly beneath the Nicoya Peninsula in Costa Rica. The event was anticipated given the history of frequent large earthquakes and recent GPS results. Strain accumulation observed before and coseismic slip observed during the earthquake create a novel and important data set, offering a unique look at the strain and locking behavior around a large megathrust environment. Given this geodetic data, and a newly developed regional 3‐D subduction interface, we develop a regionally appropriate finite element model to evaluate the role of interface topography in generating interseismic locking and ultimately coseismic slip following the 2012 earthquake. We find that the interface is most strongly coupled in a patch immediately beneath the central portion of Nicoya in an area where a topographic high in the downgoing Cocos Plate is resisting further subduction. This zone is the dominant slip environment in the 2012 earthquake. Reevaluation of the interseismic locking over 62 years before the most recent event finds that the total accumulated moment potential (M0 = 3.48 × 1020 N m) well matches the total moment release in the 2012 rupture found here (M0 = 3.73 × 1020 N m, Mw 7.68), with rupture extending to the SE outside of the strongly locked region, possibly as early afterslip. In contrast to a prior study, little locking is required immediately offshore Nicoya—a conclusion important for understanding the rupture area of the 2012 event, regional tsunami potential, and relation with regionally observed shallow slow‐slip events.

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Section: Resultsmentioning

confidence: 83%

“…[] and Liu et al . [], 3.4 × 10 20 Nm and 3.46 × 10 20 Nm, respectively. The majority of slip is concentrated beneath the central portion of the Nicoya Peninsula, primarily north and downdip of the earthquake nucleation point or epicenter (shown as a star in Figure and elsewhere).…”

Section: Resultsmentioning

confidence: 99%

Structural asperity focusing locking and earthquake slip along the Nicoya megathrust, Costa Rica

Kyriakopoulos

Newman

2016

JGR Solid Earth

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“…Large shallow coseismic slip occurred in the 2015 Illapel (e.g., Li et al, 2016;Melgar et al, 2016), 2011 Tohoku (e.g., Lay et al, 2011b;Iinuma et al, 2012;Ozawa et al, 2012;Satake et al, 2013;Romano et al, 2014;Bletery et al, 2014;Melgar and Bock, 2015;Lay, 2017), 2010 Maule (e.g., Vigny et al, 2011;Yue et al, 2014b;Yoshimoto et al, 2016;Maksymowicz, et al, 2017), and 2004 Sumatra (e.g., Ammon et al, 2005;Rhie et al, 2007;Fujii and Satake, 2007) events, accompanying slip on the downdip portions of the megathrusts. In other cases, such as the 2014 Iquique, Chile (e.g., Lay et al, 2014;Hayes et al, 2014b), 2012 Nicoya, Costa Rica (e.g., Yue et al, 2013;Liu et al, 2015), 2003 Tokachi-oki, Japan (e.g., Miyazaki and Larson, 2008;Romano et al, 2010), and 2007 Pisco, Peru, ruptures (e.g., Lay et al, 2010a;Sladen et al, 2010), slip was concentrated on the central or deeper portion of the rupture zone, with no shallow coseismic slip.…”

Section: Spatial Variations Of Slipmentioning

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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“…The most recent large earthquake was the 5 September 2012 moment magnitude ( M w ) 7.6 Nicoya earthquake (Figure ), which was preceded by a 9 day foreshock sequence [ Walter et al , ]. This event nucleated 10 km offshore at 13 km depth along the interface [ Yue et al , ], with rupture concentrating downdip and beneath the peninsula [ Yue et al , ; Protti et al , ; Liu et al , ; Kyriakopoulos and Newman , ]. The approximately 110 by 50 km coseismic rupture area [ Liu et al , ] is shown by Protti et al [] to roughly align with the region of significant (≥50%) previous interseismic locking [ Feng et al , ].…”

Section: Introductionmentioning

confidence: 99%

“…This event nucleated 10 km offshore at 13 km depth along the interface [ Yue et al , ], with rupture concentrating downdip and beneath the peninsula [ Yue et al , ; Protti et al , ; Liu et al , ; Kyriakopoulos and Newman , ]. The approximately 110 by 50 km coseismic rupture area [ Liu et al , ] is shown by Protti et al [] to roughly align with the region of significant (≥50%) previous interseismic locking [ Feng et al , ]. A potential zone of unreleased slip in the Protti et al [] model, located immediately offshore and north west of the hypocenter [ Protti et al , , Figure 4b], was shown by Kyriakopoulos and Newman [] to be partially diminished in amplitude and spatial extent when a fully 3‐D slab geometry is implemented.…”

Section: Introductionmentioning

confidence: 99%

Large and primarily updip afterslip following the 2012 M_w 7.6 Nicoya, Costa Rica, earthquake

et al. 2017

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We present detailed surface measurements of the first 3.5 years of postseismic deformation following the 5 September 2012 moment magnitude (Mw) 7.6 Nicoya, Costa Rica, earthquake. The dominant signal in the first 2.5 years is uniform horizontal trenchward motion totaling 7–26 cm across 40 stations. Trenchward velocity is strongly diminished by mid‐2014 and appears by 2016 to have begun reversing. We invert the first 2.5 years to determine the corresponding afterslip on a detailed 3‐D interface. Results show significant afterslip both updip and downdip of the main coseismic rupture zone, with as much as 1.7 m of offset in two patches at 15–20 km depth and immediately updip of the maximum coseismic slip. This updip slip represents an important mechanism to address unrelieved interseismic locking, although sufficient strain energy remains to generate up to a Mw 7.1 event near the coastline. The afterslip patches are anticorrelated with strongly clustered aftershocks at the same depth, which is indicative of varying frictional behavior along strike. An additional patch of slip is colocated with reoccurring slow‐slip events beneath the Gulf of Nicoya. The magnitude of the observed slip, however, cannot be sufficiently explained by the known slow‐slip events. Ongoing measurements will be crucial to understanding the relocking process in Nicoya.

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Rupture processes of the 2012 September 5M_w7.6 Nicoya, Costa Rica earthquake constrained by improved geodetic and seismological observations

Cited by 14 publications

References 32 publications

Structural asperity focusing locking and earthquake slip along the Nicoya megathrust, Costa Rica

Structural asperity focusing locking and earthquake slip along the Nicoya megathrust, Costa Rica

Subduction zone megathrust earthquakes

Large and primarily updip afterslip following the 2012 M_w 7.6 Nicoya, Costa Rica, earthquake

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Rupture processes of the 2012 September 5Mw7.6 Nicoya, Costa Rica earthquake constrained by improved geodetic and seismological observations

Cited by 14 publications

References 32 publications

Structural asperity focusing locking and earthquake slip along the Nicoya megathrust, Costa Rica

Structural asperity focusing locking and earthquake slip along the Nicoya megathrust, Costa Rica

Subduction zone megathrust earthquakes

Large and primarily updip afterslip following the 2012 Mw 7.6 Nicoya, Costa Rica, earthquake

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Rupture processes of the 2012 September 5M_w7.6 Nicoya, Costa Rica earthquake constrained by improved geodetic and seismological observations

Large and primarily updip afterslip following the 2012 M_w 7.6 Nicoya, Costa Rica, earthquake