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Earthquakes from the Global CMT catalog. Selected subduction thrust events from the Global CMT catalog for 1976-2016. Other annotations are the same as in Fig. 1
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Abstract Oblique convergent margins often host forearc slivers separated by the subduction interface and a trench parallel strike-slip fault system in the overriding plate. Mexican oblique subduction setting led to the formation of a forearc sliver and accomodation of part of the slip at the bounding system of strike-slip faults. The Xolapa sliver...
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Context 1
... to the local strike of the trench (DeMets 1992). The trench is approximated with the small circle with the pole at − 80.11 • E , 51.01 • N and radius of 4256.734 km. Trench normal lays in the direction to the pole of the small circle (Fig. 2). Selected data from the Global CMT catalog for thrust events in 1976-2016 are analyzed for the same area (Fig. 3) and compared to the results from the local catalogs. 83 events with M w ≥ 4.7 have been selected. Selection criteria are the same as for the local catalog. Additionally only the events with percentage of double couple DC ≥ 80% are considered (see Additional file 2). The area is divided into three regions (Fig. ...
Context 2
... are analyzed for the same area (Fig. 3) and compared to the results from the local catalogs. 83 events with M w ≥ 4.7 have been selected. Selection criteria are the same as for the local catalog. Additionally only the events with percentage of double couple DC ≥ 80% are considered (see Additional file 2). The area is divided into three regions (Fig. ...
Context 3
... of convergence velocity and obliquity to the southeast, the slip rate on the LVC fault is decreasing contrary to what would be expected. Based on this observation, we assume a compressive deformation of the Xolapa sliver likely caused by the presence of a buttressing structure, such as subducting seamount chains in Oaxaca, at its leading edge (Fig. 3). Detailed analysis of GPS time series and a refined fault trace mapping, especially in Oaxaca, will allow retrieving more information on the activity of forearc faults and associated seismic risk. Table 2 Mean strike-slip components of the Xolapa sliver motion ( V ss ) for different distances from the trench calculated using data from ...
Citations
... Other strike-slip mechanisms for shallow events (z ≤ 50 km) are found in the gulf of Tehuantepec area, which are probably related to the Isthmus fault (Barrier et al., 1998) (Figure 2). West of 96° W, strikeslip mechanisms for shallow (z ≤ 50 km) earthquakes probably correspond to activity along the Chacalapa (or La Venta-Chacalapa) fault zone (Gaidzik et al., 2016;Kazachkina et al., 2019; 2020) ( Figure 5). ...
... A contradiction arises from the fact that along the CAVA, documented motion, from earthquake focal mechanisms (e.g., Guzmán-Speziale et al., 2005) and GPS (Lyon-Caën et al., 2006;Franco et al., 2012; Álvarez- Ellis et al., 2019;Garnier et al., 2021) is right-lateral, while the northernmost forearc offshore southern Mexico, is flanked by the Tonalá fault, a left-lateral structure (García-Palomares, 1978;Authemayou et al., 2012;Molina-Garza et al., 2015). To complicate matters further, Kazachkina et al. (2019;2020) suggest the presence of a Xolapa sliver, located northwest of the Central America forearc, parallel to the Middle America trench, and being displaced to the southeast along the 650-km long Chacalapa fault at a rate of 5.6 to 10 mm/yr (Kazachkina et al., 2019;2020) (Figure 7). The role of these two forearc sliver in the tectonics of the triple junction is still an open question. ...
... A contradiction arises from the fact that along the CAVA, documented motion, from earthquake focal mechanisms (e.g., Guzmán-Speziale et al., 2005) and GPS (Lyon-Caën et al., 2006;Franco et al., 2012; Álvarez- Ellis et al., 2019;Garnier et al., 2021) is right-lateral, while the northernmost forearc offshore southern Mexico, is flanked by the Tonalá fault, a left-lateral structure (García-Palomares, 1978;Authemayou et al., 2012;Molina-Garza et al., 2015). To complicate matters further, Kazachkina et al. (2019;2020) suggest the presence of a Xolapa sliver, located northwest of the Central America forearc, parallel to the Middle America trench, and being displaced to the southeast along the 650-km long Chacalapa fault at a rate of 5.6 to 10 mm/yr (Kazachkina et al., 2019;2020) (Figure 7). The role of these two forearc sliver in the tectonics of the triple junction is still an open question. ...
We present a summary of the tectonic elements of the North America-Caribbean-Cocos triple junction area. In the vicinity of the triple junction, displacement related to the North America-Caribbean plate boundary takes place along the left-lateral Motagua-Polochic fault system, and convergence between the Cocos and the other two plates occurs along the Middle America trench. The trace of the Motagua-Polochic system is lost at its westernmost end and does not reach the convergent boundary. Deformation of the plate boundary in this location is then distributed along a system of reverse faults (the Reverse-faults tectonic province), a system of left-lateral faults (Strike-slip faults province), two or more large NW-SE oriented left-lateral faults (Angostura and Concordia faults), and a left-lateral fault (Tonalá) that might be construed as the continuation of the Polochic fault along the southern border of the Chiapas Massif. Somewhere within this deformation zone, transition in overriding plate between North America and Caribbean takes place, but it is not clear exactly where. It is probably at about longitude 96° W because both the dip and the shape of the subducted Cocos slab change significantly at this longitude.
... These events are related to oblique extension and strike-slip in NNW-SSE kilometric fault system during the Oligocene (e.g., Taxco-San Miguel de Allende fault system; Alaniz-Álvarez et al., 2002a). Additionally, some strike-slip faults located in the southwest coast of Mexico, which are parallel to the Middle American trench have been recognized (Gaidzik et al., 2016;Kazachkina et al., 2019). The activity of these faults is related to the oblique subduction (~10 • ) in southwest coast of Mexico (Gaidzik et al., 2016;Kazachkina et al., 2019). ...
... Additionally, some strike-slip faults located in the southwest coast of Mexico, which are parallel to the Middle American trench have been recognized (Gaidzik et al., 2016;Kazachkina et al., 2019). The activity of these faults is related to the oblique subduction (~10 • ) in southwest coast of Mexico (Gaidzik et al., 2016;Kazachkina et al., 2019). The Tenochtitlan fault system is constituted by faults and crustal fractures (observed in regional maps) that have a strike perpendicular to the Middle American Trench (Fig. 1). ...
A NE-SW fault system, observed in the northeast portion of the eastern sector of the Trans-Mexican Volcanic Belt, has been active since the Pliocene-Holocene time with dip-slip kinematics. These NE-SW faults belong to the Tenochtitlan fault system that extends from the southwest coast of Mexico to the NE zone of the Mexico basin. The length of this fault system suggests a complex deformation history, which is unknown before the Pliocene. In addition, the kinematics of the NE-SW faults and the tectonic conditions are unknown before their current activity. In this study, we investigate the geometry and kinematics of the NE-SW faults in the Miocene rocks in the central part of the Mexico basin (Guadalupe Range) for to know the kinematics of these faults during the Late Miocene time. Our results suggest that the Miocene rocks record two deformation events, one event is related to crustal shortening which produced a strike-slip activity in the NE-SW faults during the Late Miocene. The second deformation event is associated with crustal extension and the activity of the NE-SW faults with dip-slip kinematics. This extensional event was active during the Pliocene-Holocene. The re-activation analysis and our observations in the Guadalupe Range suggests that the NE-SW normal faults in the Tizayuca-Chignahuapan region are the product of the re-activation of previous NE-SW strike-slip faults. The change in the kinematics of the NE-SW faults explains the complex geometry of the damage zone and the high amount of the geological fractures in the Miocene rocks of the Mexico Basin. The activity type of the NE-SW faults is probably related to the dynamic of the subduction process in the southwest of Mexico, associated with the change in the inclination (decrease) and the convergence velocity of the Cocos Plate.
... These events are related to oblique extension and strike-slip in NNW-SSE kilometric fault system during the Oligocene (e.g., Taxco-San Miguel de Allende fault system; Alaniz-Álvarez et al., 2002a). Additionally, some strike-slip faults located in the southwest coast of Mexico, which are parallel to the Middle American trench have been recognized (Gaidzik et al., 2016;Kazachkina et al., 2019). The activity of these faults is related to the oblique subduction (~10 • ) in southwest coast of Mexico (Gaidzik et al., 2016;Kazachkina et al., 2019). ...
... Additionally, some strike-slip faults located in the southwest coast of Mexico, which are parallel to the Middle American trench have been recognized (Gaidzik et al., 2016;Kazachkina et al., 2019). The activity of these faults is related to the oblique subduction (~10 • ) in southwest coast of Mexico (Gaidzik et al., 2016;Kazachkina et al., 2019). The Tenochtitlan fault system is constituted by faults and crustal fractures (observed in regional maps) that have a strike perpendicular to the Middle American Trench (Fig. 1). ...
... However, the basal detachment of Chortís from its lower crust (Xolapa Complex) implies that that fault system had an even greater extension reaching the northern boundary of the Xolapa belt. New estimates of long-term velocities of GPS stations in southern Mexico reveal a currently active, strike-slip fault system extending along the northern Xolapa boundary (La Venta-Chacalapa fault system; Kazachkina et al., 2019Kazachkina et al., , 2020. We thus propose that a precursor of this active fault system accommodated the lateral detachment of Chortís upper crust from the adjacent Mixteco-Oaxaca Block (Figs. 14 and 17b). ...
Three successive strain regimes spanning up to ~16 million years were identified from the field, structural and geochronological analyses in Upper Eocene-Oligocene migmatites of the Xolapa Complex around the Puerto Escondido longitude (~97°W), in southern Mexico. A west-facing asymmetric folding affecting diatexites at ca. 38–31 Ma defines Regime A. Regimes B and C affected younger metatexites. Regime B recorded an outward extension at ca. 31–25 Ma, whereas Regime C occurred at ca. 25–22 Ma as NE-directed thrusting. By coupling the Upper Cretaceous-Oligocene tectonic framework of southern Mexico with the dynamics and timing of the identified strain regimes, we interpret that Regimes A to C recorded distinct stages of the separation and eastward migration of the Chortís Block, viewed as a continuous geodynamic episode. According to our proposal, the upper and lower crust of Chortís adjacent to nuclear Mexico were vertically decoupled before its separation by the presence of pre-Eocene crustal anisotropies. Regime A occurred when the Chortís Block rode over the Xolapa Complex during its initial eastward escape. Since this episode, the Chortís Block (upper crust) was captured by the Caribbean plate, whereas the Xolapa Complex (lower crust) remained as the southernmost North America plate. Chortís eastward migration and the consequent unloading of its decoupled lower crust triggered anatexis, isostatic adjustments, and diachronous uplift of the Xolapa Complex (Regime B). The progressive substitution of Chortís by its thinner lower crust in the tectonic configuration next to nuclear Mexico gradually enhanced the local convergence rate between the Farallon/Cocos plate and just-severed North America. The Farallon/Cocos plate was accreted to North America (Regime C) after a critical lengthening of the uprising lower crust along the southern Mexican margin. The local increase of the convergence rate promoted the landward consumption of the Xolapa Complex by subduction erosion since 22 Ma.
... Ces vitesses sont plus élevées sur la partie Est en raison de la localisation du pôle de rotation des deux plaques au large de la péninsule de Baja-California. La direction de convergence de la subduction entre ces deux plaques est légèrement oblique (10 • par rapport à la perpendiculaire à la fosse), ce qui se traduit par un partitionnement le long d'un système de failles crustales décrochantes sénestres appelé La Venta-Chacalapa (Gaidzik et al., 2016;Kazachkina et al., 2020Kazachkina et al., , 2019. Ce système délimite le bloc tectonique de Xolapa par rapport à la plaque Nord Amérique (Figure 1.7) . ...
La multiplication depuis 20 ans d'observations de déformations transitoires au cours du cycle sismique a mis en avant la question de l'impact de ces déformations dans l'estimation de l'aléa sismique. Ainsi, dans les zones de subduction, le rôle des séismes lents sur la variabilité spatiale et temporelle du couplage intersismique et sur l'existence de lacunes sismiques est une question de première importance. Nous avons abordé cette problématique par l'analyse d'observations géodésiques et par la modélisation numérique, en se focalisant sur la subduction mexicaine. Cette zone est une cible pertinente pour étudier ces questions en raison de la présence de séismes lents qui font partie des plus grands observés au monde. La géométrie de cette subduction est également favorable aux observations géodésiques. Un premier volet de cette thèse a été consacré à l’étude du séisme lent de 2017-2018 qui a duré plusieurs mois dans la région de Guerrero. Pour cela, de nouvelles observations ont été faites par interférométrie radar satellitaires (InSAR) utilisant les données Sentinel-1, combinées aux données du réseau GPS permanent. Les données InSAR ont permis d’améliorer significativement la couverture et la résolution spatiale des mesures de déformation du sol par rapport aux études précédentes. La fréquence d’acquisition de ces données est de 6 à 12 jours. Un travail méthodologique sur l’extraction du signal tectonique inclus dans les séries temporelles InSAR a été nécessaire en raison de la grande superficie de la zone d’étude où sont présents de fort gradients topographiques. Deux méthodes de séparation de sources ont été employées. La première approche est une décomposition paramétrique, dans laquelle la forme fonctionnelle des signaux de déformation est imposée, et les signaux atmosphériques sont décrits en utilisant comme contrainte des séries temporelles de délais troposphériques zénithaux issus du GPS. La seconde approche utilise l’analyse en composantes indépendantes (ICA) des séries temporelles InSAR, ne nécessitant pas d’à priori sur le signal recherché. Les deux méthodes fournissent des résultats cohérents et permettent de séparer le signal atmosphérique, sans corrections préalables, du signal tectonique. A partir des cartes de séries temporelles de déplacements validées par les mesures GPS, le glissement du séisme lent sur l’interface de subduction est inversé. La distribution spatiale du glissement est cohérente avec celle des évènements précédents et confirme une localisation à la limite de la zone sismique. L’influence de séismes distants sur la cinématique de ce type d’évènement est également confirmée par ces observations.Dans une seconde partie, les déformations intersismiques sur une zone couvrant environ 1000 km de la subduction mexicaine de Jalisco à Oaxaca sont également analysées à partir de mesures InSAR et GPS. Les variations latérales de couplage le long de la subduction entre 2016 et 2019 sont établies pour la première fois de façon homogène sur l’ensemble de cette zone. Entre Michaocan et Jalisco, où de grands séismes ont eu lieu, on retrouve une zone à fort couplage. L’analyse montre bien l’importance que peuvent avoir à l’échelle de temps de quelques années les signaux transitoires comme les séismes lents sur la variabilité du couplage mesurée par géodésie spatiale. La dernière partie de cette thèse, aborde ce problème par une modélisation numérique du cycle sismique sur un plan de faille en 3D, basée sur des lois de friction de type « rate and state ». Cette modélisation permet de reproduire certaines caractéristiques de subduction mexicaine et de replacer les 20 ans d’observations géodésiques à l’échelle de plusieurs cycles sismiques. Les résultats préliminaires donnent des pistes de réflexions intéressantes sur la question de la possibilité qu’un séisme puisse se produire dans la lacune sismique de Guerrero et sur le rôle des séismes lents sur le faible couplage observé dans cette région.
... mm/year (see Supplementary Figure A3), which is closer to the V SS values obtained with the GPS. The large dispersion of CMT slip vector angles is apparently related to uncertainties in the CMT catalog, complicated structures of the LVC fault system (Ramírez-Herrera et al., 2018) and the Xolapa sliver, inhomogeneous Co-NA plate interface, variation of the plate coupling (e.g., Kostoglodov and Ponce, 1994), and more complicated than just a simple friction rheology of the fault (Kazachkina et al., 2019). Furthermore, observed dispersion is partially related to the increase of the Co-NA convergence velocity southeastward along the MAT. ...
New estimates of long-term velocities of permanent GPS stations in Southern Mexico reveal that the geologically discernible ∼650-km long shear zone, which strikes parallel to the Middle America trench, is active. This left-lateral strike-slip, La Venta–Chacalapa (LVC) fault system, is apparently associated with a motion of the Xolapa terrain and at the present time is the northern boundary of a ∼110–160-km wide forearc sliver with a sinistral motion of 3–6 mm/year with respect to the North America plate. This sliver is the major tectonic feature in the Guerrero and Oaxaca regions, which accommodates most of the oblique component of the convergence between the Cocos and North America plates. Previous studies based purely on the moment tensor coseismic slips exceedingly overestimated the sliver inland extent and allocated its northern margin on or to the north of the Trans-Mexican Volcanic Belt. While the LVC fault system probably slips slowly over geologic scale time and there is not any historic evidence of large earthquakes on the fault so far, its seismic potential could be very high, assuming a feasible order of ∼10³ years recurrence cycle. A detailed analysis of long-term position time series of permanent GPS stations in the Guerrero and Oaxaca states, Southern Mexico discards previous models and provides clear evidence of an active LVC fault zone bounding the Xolapa forearc sliver. The southeastward motion of this sliver may have persisted for the last ∼8–10 Million year and played an important role in the tectonic evolution of the region.
On 20 March 2012, a Mw 7.5 thrust earthquake started a series of seven large events (7.0 ≤ Mw ≤ 8.2) that struck central Mexico during a period of 9 years (2012–2021). Before this event, the Mexican subduction zone did not experience significant subduction earthquakes (Mw > 7.0) for at least 12 years. Five of the events occurred in the plate interface, resulting in a significantly larger interplate slip rate in the states of Oaxaca and Guerrero. In this study, we explore how an aseismic slip transient caused by the 2012 Mw 7.5 earthquake affected the Oaxaca region and whether this earthquake had a causal relationship with the Mw 7.2 Pinotepa Nacional event that took place six years later in a nerby zone. To this end, we identified and analyzed characteristic repeating earthquakes along the Mexican subduction zone for assessing the plate interface slip history and found a remarkable increase in the aseismic slip rate following the 2012 mainshock, which suggests a long‐standing slip perturbation near the trench in Oaxaca that continued until the Pinotepa Nacional earthquake of 2018.
