Seismicity and Crustal Structure of the Polochic-Motagua Fault System Area (Guatemala)

Franco, Aurore; Molina, Emilio; Lyon‐Caen, H.; Vergne, Jérôme; Monfret, Tony; Nercessian, A.; Cortez, Solymar Ayala; Flores, Omar; Monterosso, D.; Requenna, J.

doi:10.1785/gssrl.80.6.977

Cited by 17 publications

(28 citation statements)

References 32 publications

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“…Numerical modeling, based on seismic tensors and GPS velocity fields [ Álvarez‐Gómez et al , 2008; Rodriguez et al , 2009], assigns an important role to the fore‐arc sliver and the arcuate shape of the transform boundary. In this model the western edge of the Chortís block is regarded as partially pinned to North America, and weak coupling occurs in the fore‐arc sliver across the Caribbean/Cocos subduction interface, while stronger coupling occurs across the North American/Cocos subduction interface [ Franco et al , 2009]. The seismotectonic model of Guzmán‐Speziale [2009] arrives at the same conclusion, inasmuch as the Chortís block is being extruded toward the ESE by convergence between the North America and Cocos plates.…”

Section: Alternative Models For Nacc Triple Junctionmentioning

confidence: 99%

The Caribbean–North America–Cocos Triple Junction and the dynamics of the Polochic–Motagua fault systems: Pull‐up and zipper models

et al. 2011

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International audienceThe Polochic-Motagua fault systems (PMFS) are part of the sinistral transform boundary between the North American and Caribbean plates. To the west, these systems interact with the subduction zone of the Cocos plate, forming a subduction-subduction-transform triple junction. The North American plate moves westward relative to the Caribbean plate. This movement does not affect the geometry of the subducted Cocos plate, which implies that deformation is accommodated entirely in the two overriding plates. Structural data, fault kinematic analysis, and geomorphic observations provide new elements that help to understand the late Cenozoic evolution of this triple junction. In the Miocene, extension and shortening occurred south and north of the Motagua fault, respectively. This strain regime migrated northward to the Polochic fault after the late Miocene. This shift is interpreted as a "pull-up" of North American blocks into the Caribbean realm. To the west, the PMFS interact with a trench-parallel fault zone that links the Tonala fault to the Jalpatagua fault. These faults bound a fore-arc sliver that is shared by the two overriding plates. We propose that the dextral Jalpatagua fault merges with the sinistral PMFS, leaving behind a suturing structure, the Tonala fault. This tectonic "zipper" allows the migration of the triple junction. As a result, the fore-arc sliver comes into contact with the North American plate and helps to maintain a linear subduction zone along the trailing edge of the Caribbean plate. All these processes currently make the triple junction increasingly diffuse as it propagates eastward and inland within both overriding plates

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Section: Alternative Models For Nacc Triple Junctionmentioning

confidence: 99%

The Caribbean–North America–Cocos Triple Junction and the dynamics of the Polochic–Motagua fault systems: Pull‐up and zipper models

et al. 2011

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“…The seismic activity along the Polochic‐Motagua fault system poses a threat to some 70% of the total population of Guatemala. Both faults have generated a number of recorded and/or historically documented earthquakes [ White , 1984, 1985; Plafker , 1976; White and Harlow , 1993; Ambraseys and Adams , 2001; Franco et al , 2009]. Recorded shallow earthquakes are rather uniformly distributed along the two major faults without any obvious clustering [ Franco et al , 2009].…”

Section: Tectonic Setting and Seismic Activity Of The Polochic Faultmentioning

confidence: 99%

“…Both the Polochic and Motagua faults exhibit morphological and historical evidence of ongoing seismic activity [ Kupfer and Godoy , 1967; Schwartz et al , 1979; White , 1984, 1985; White and Harlow , 1993; Kovach and Nur , 2006; Franco et al , 2009]. The Motagua fault generated an earthquake of magnitude 7.5 in 1976, which claimed ∼23,000 lives, and evidence for at least one major paleo‐earthquake was found in the 1100‐year‐old Mayan city of Quiriguá, located next to the active trace of the fault [ Kovach and Nur , 2006].…”

Section: Introductionmentioning

confidence: 99%

Quaternary seismo‐tectonic activity of the Polochic Fault, Guatemala

Authémayou¹,

Brocard²,

Teyssier³

et al. 2012

J. Geophys. Res.

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[1] The Polochic-Motagua fault system is part of the sinistral transform boundary between the North American and Caribbean plates in Guatemala and the associated seismic activity poses a threat to $70% of the country's population. The aim of this study is to constrain the Late Quaternary activity of the Polochic fault by determining the active structure geometry and quantifying recent displacement rates as well as paleo-seismic events. Slip rates have been estimated from offsets of Quaternary volcanic markers and alluvial fan using in situ cosmogenic 36 Cl exposure dating. Holocene left-lateral slip rate and Mid-Pleistocene vertical slip rate have been estimated to 4.8 AE 2.3 mm/y and 0.3 AE 0.06 mm/y, respectively, on the central part of the Polochic fault. The horizontal slip rate is within the range of longer-term geological slip rates and short-term GPS-based estimates. In addition, the non-negligible vertical motion participates in the uplift of the block north of the fault and seems to be a manifestation of the regional, far-field stress regime. We excavated the first trench for paleo-seismological study on the Polochic fault in which we distinguish four large paleo-seismic events since 17 ky during which the Polochic fault ruptured the ground surface.

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“…Measurements on well-instrumented continental strike-slip faults find that wherever creep occurs, it remains restricted to the upper crust, above a deeper zone of either slow earthquakes and tectonic tremors4546, or above a locked, seismogenic zone that ruptures either in M4-5 earthquakes12, or in infrequent M6-7 earthquakes11. The Polochic fault currently produces micro-seismicity to a depth of 10 km and M4.5–5.5 earthquakes between 5 and 10 km23, suggesting the existence of a locked zone at depth. There is also geological evidence for past episodic, possibly seismogenic deformation at the surface24.…”

Section: Discussionmentioning

confidence: 99%

“…It has been stressed that the collective inventory of earthquakes along the Polochic and Motagua faults over the last millennium seems insufficient to accommodate the total left-lateral motion accumulated across the plate boundary over the period, suggesting a deficit of major seismic events20. Over the 20 th century however, the instrumental record of M < 5.5 earthquakes does not display a severe deficit212223. Direct geological observations of displacements across the plate boundary are thus far restricted to observations in 10–17 ky-old alluvium along the Polochic fault24.…”

Section: Settingmentioning

confidence: 99%

Guatemala paleoseismicity: from Late Classic Maya collapse to recent fault creep

Brocard

Anselmetti

Teyssier

2016

Sci Rep

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We combine ‘on-fault’ trench observations of slip on the Polochic fault (North America-Caribbean plate boundary) with a 1200 years-long ‘near-fault’ record of seismo-turbidite generation in a lake located within 2 km of the fault. The lake record indicates that, over the past 12 centuries, 10 earthquakes reaching ground-shaking intensities ≥ VI generated seismo-turbidites in the lake. Seismic activity was highly unevenly distributed over time and noticeably includes a cluster of earthquakes spread over a century at the end of the Classic Maya period. This cluster may have contributed to the piecemeal collapse of the Classic Maya civilization in this wet, mountainous southern part of the Maya realm. On-fault observations within 7 km of the lake show that soils formed between 1665 and 1813 CE were displaced by the Polochic fault during a long period of seismic quiescence, from 1450 to 1976 CE. Displacement on the Polochic fault during at least the last 480 years included a component of slip that was aseismic, or associated with very light seismicity (magnitude <5 earthquakes). Seismicity of the plate boundary is therefore either non-cyclic, or dominated by long-period cycles (>1 ky) punctuated by destructive earthquake clusters.

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Seismicity and Crustal Structure of the Polochic-Motagua Fault System Area (Guatemala)

Cited by 17 publications

References 32 publications

The Caribbean–North America–Cocos Triple Junction and the dynamics of the Polochic–Motagua fault systems: Pull‐up and zipper models

The Caribbean–North America–Cocos Triple Junction and the dynamics of the Polochic–Motagua fault systems: Pull‐up and zipper models

Quaternary seismo‐tectonic activity of the Polochic Fault, Guatemala

Guatemala paleoseismicity: from Late Classic Maya collapse to recent fault creep

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