The 2012 August 27<i>M</i><sub>w</sub>7.3 El Salvador earthquake: expression of weak coupling on the Middle America subduction zone

Geirsson, H.; LaFemina, Peter; DeMets, Charles; Hernández, Daniela; Mattioli, G. S.; Rogers, Robert D.; Rodriguez, M; Marroquín, Griselda; Tenorio, Virginia

doi:10.1093/gji/ggv244

Cited by 20 publications

(27 citation statements)

References 43 publications

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“…Several authors (e.g. Álvarez-Gómez et al, 2008;Correa-Mora et al, 2009;LaFemina et al, 2009;Franco et al, 2012;Geirsson et al, 2015) Ridge collision offshore Costa Rica, as has been proposed by previous authors (LaFemina et al, 2009). Another important result of the latter is the definition of ~60-km-wide extensional zone with E-W elongation in the Gulf of Fonseca and eastern El Salvador that may be accompanied by bookshelf faulting (e.g.…”

Section: Previous Geodetic Studiesmentioning

confidence: 80%

“…2). However, on 27 th of August 2012 the last major megathrust earthquake (M w 7.3) occurred offshore El Salvador (Geirsson et al, 2015). Until this event, the region offshore was considered a seismic gap for nearly a century.…”

Section: Instrumental and Historical Seismicitymentioning

confidence: 99%

“…In order to interpret the GPS results in terms of regional deformation associated with the ESFZ, we considered the coseismic deformation resulting from regional earthquakes which occurred in the 2007-2012 period, with M w > 6.0 and depth < 60 km. It should be noted that the data were recorded before to the 2012 August 27 M w 7.3 El Salvador subduction zone earthquake (Geirsson et al, 2015). Therefore, we only took into account the M w = 7.3 2009…”

Section: Gps Data Processingmentioning

confidence: 99%

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Present-day crustal deformation along the El Salvador Fault Zone from ZFESNet GPS network

et al. 2016

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This paper presents the results and conclusions obtained from new GPS data compiled along the El Salvador Fault Zone (ESFZ). We calculated a GPS-derived horizontal velocity field representing the present-day crustal deformation rates in the ESFZ based on the analysis of 30 GPS campaign stations of the ZFESNet network, measured over a 4.5 year period from 2007 to 2012. The velocity field and subsequent strain rate analysis clearly indicate dextral strike-slip tectonics with extensional component throughout the ESFZ. Our results suggest that the boundary between the Salvadoran forearc and Caribbean blocks is a deformation zone which varies along the fault zone. We estimate that the movement between the two blocks is at least ~12 mm yr-1. From west to east, this movement is variably distributed between faults or segments of the ESFZ. We propose a kinematic model with three main blocks; the Western, Central and Eastern blocks delimited by major faults. For the first time, we were able to provide a quantitative measure of the present-day horizontal geodetic slip rate of the main segments of ESFZ, ranging from ~2 mm yr-1 in the east segment to ~8 mm yr-1 , in the west and central segments. This study contributes new kinematic and slip rate

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Section: Previous Geodetic Studiesmentioning

confidence: 80%

Section: Instrumental and Historical Seismicitymentioning

confidence: 99%

Section: Gps Data Processingmentioning

confidence: 99%

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Present-day crustal deformation along the El Salvador Fault Zone from ZFESNet GPS network

et al. 2016

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“…Similar rapid afterslip in the first day has been seen after other events: 20% of coseismic displacements in first day after the M w 6.3, 2009, L'Aquila, Italy, earthquake (Yano et al, 2014); 7% in the first 3 hr after the M w 7.6, 2012, Nicoya, Costa Rica, earthquake (Malservisi et al, 2015); and 30% in the first 24 hr after both the M w 7.6 1994 Sanriku-Haruka-Oki, Japan, earthquake (Heki and Tamura, 1997) and the M w 7.8, 2010, Mentawai, Indonesia event (Hill et al, 2012). Furthermore, large afterslip to coseismic slip ratios have been observed for several other earthquakes in the Middle America Trench, such as the Pinotepa-Nacional/Ometepec M w 7.5 earthquake in 2012 (Graham et al, 2014), the M w 7.2, 2012, El Salvador earthquake, and the M w 6.9, 2004, 9 October, Nicaragua earthquake (Geirsson et al, 2015).…”

Section: Journal Of Geophysical Research: Solid Earthmentioning

confidence: 99%

Was the 9 October 1995 M_w 8 Jalisco, Mexico, Earthquake a Near‐Trench Event?

et al. 2018

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The behavior of slip close to the trench during earthquakes is not well understood, and observations of large earthquakes breaking the near trench fault surface are rare. The 1995 Mw 8.0 Jalisco earthquake seems to have broken the near‐trench area, as evidenced by large Ms‐Mw disparity, small high‐frequency radiated energy compared to total energy, and low Er/M0 ratios, in addition to several finite slip models showing large slip near the trench. However, slip models obtained using campaign Global Positioning System data suggest slip near shore. In this study we try to answer whether this event was a near‐trench event or not, by inverting teleseismic P, S, Rayleigh, and Love waves, as well as campaign Global Positioning System static offsets, either separately or jointly, to obtain the slip distribution on the fault as a function of time. We find two possible end‐member scenarios consistent with observed data: (1) coseismic slip distributed between coast and trench and no (or very little) postseismic slip and (2) coseismic slip principally near the trench with large (up to 1.8 m) aseismic slip occurring in the first 5–10 days after the earthquake, with a total moment corresponding to 16% of that of the event. We are unable to distinguish between these two end‐member scenarios by tsunami modeling and finally are neither able to conclude or exclude that the event was a typical near trench event.

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“…Prior to the M w = 7.3 2012 El Salvador subduction-thrust earthquake, the last notable subduction-thrust earthquake to rupture the El Salvador trench segment was in 1915 and possibly earlier (White et al 2004). The coseismic slip estimated for the 2012 earthquake from modelling of the coseismic offsets measured at GPS sites onshore from the earthquake averaged only 500-800 mm (Geirsson et al 2015;Ellis et al 2018). For comparison, our newly estimated Cocos-forearc sliver angular velocity (Table 1) predicts that the cumulative plate convergence was ≈7300 mm between 1915 and 2012 at the 2012 earthquake location.…”

Section: Reconciling Low Subduction Locking With the 2012 El Salvadormentioning

confidence: 99%

GPS constraints on deformation in northern Central America from 1999 to 2017, Part 2: Block rotations and fault slip rates, fault locking and distributed deformation

Ellis

DeMets

McCaffrey

et al. 2019

Geophysical Journal International

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The 2012 August 27M_w7.3 El Salvador earthquake: expression of weak coupling on the Middle America subduction zone

Cited by 20 publications

References 43 publications

Present-day crustal deformation along the El Salvador Fault Zone from ZFESNet GPS network

Present-day crustal deformation along the El Salvador Fault Zone from ZFESNet GPS network

Was the 9 October 1995 M_w 8 Jalisco, Mexico, Earthquake a Near‐Trench Event?

GPS constraints on deformation in northern Central America from 1999 to 2017, Part 2: Block rotations and fault slip rates, fault locking and distributed deformation

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The 2012 August 27Mw7.3 El Salvador earthquake: expression of weak coupling on the Middle America subduction zone

Cited by 20 publications

References 43 publications

Present-day crustal deformation along the El Salvador Fault Zone from ZFESNet GPS network

Present-day crustal deformation along the El Salvador Fault Zone from ZFESNet GPS network

Was the 9 October 1995 Mw 8 Jalisco, Mexico, Earthquake a Near‐Trench Event?

GPS constraints on deformation in northern Central America from 1999 to 2017, Part 2: Block rotations and fault slip rates, fault locking and distributed deformation

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The 2012 August 27M_w7.3 El Salvador earthquake: expression of weak coupling on the Middle America subduction zone

Was the 9 October 1995 M_w 8 Jalisco, Mexico, Earthquake a Near‐Trench Event?