Low Angle Contact Between the Oaxaca and Juárez Terranes Deduced From Magnetotelluric Data

Arzate-Flores, Jorge; Molina-Garza, Roberto S.; Corbo-Camargo, Fernando; Márquez-Ramírez, Víctor Hugo

doi:10.1007/978-3-319-51529-8_9

Cited by 4 publications

(16 citation statements)

References 42 publications

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“…This anomaly agrees with our proposed depth of the Moho up to 50 km from the coast. Then, between 75 and 150 km inland, our Moho depth (∼35 km) is slightly shallower than the 40-50 km observed by Arzate-Flores et al (2016). They observe a high resistivity region, which they suggest it might be associated with a dry and colder basement of the Oaxaca terrane.…”

Section: Moho Discontinuitymentioning

confidence: 46%

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Crustal structure variations in south-central Mexico from receiver functions

Rodríguez-Domínguez

Pérez‐Campos

Montealegre-Cázares

et al. 2019

Geophysical Journal International

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Summary Mexico has a complex geological history that is typified by the distinctive terranes that are found in the south-central region. Crustal thickness variations often correlate with geological terranes that have been altered by several processes in the past, for example aerial or subduction erosion, underplating volcanic material or rifting but few geophysical studies have locally imaged the entire continental crust in Mexico. In this paper, the thickness of three layers of the crust in south-central Mexico is determined. To do this, we use P- and S-wave receiver functions (RF) from 159 seismological broad-band stations. Thanks to its adaptive nature, we use an empirical mode decomposition (EMD) algorithm to reconstruct the RFs into intrinsic mode functions (IMF) in order to enhance the pulses related to internal discontinuities within the crust. To inspect possible lateral variations, the RFs are grouped into quadrants of 90°, and their amplitudes are mapped into the thickness assuming a three-layer model. Using this approach, we identify a shallow sedimentary layer with a thickness in the range of 1–4 km. The upper-crust was estimated to be of a few kilometers (<10 km) thick near the Pacific coast, and thicker, approximately 15 km in central Oaxaca and under the Trans-Mexican Volcanic Belt (TMVB). Close to the Pacific coast, we infer a thin crust of approximately 16 ± 0.9 km, while in central Oaxaca and beneath the TMVB, we observe a thicker crust ranging between 30 and 50 km ± 2.0 km. We observe a crustal thinning, of approximately 6 km, from central Oaxaca (37 ± 1.9 km) towards the Gulf of Mexico, under the Veracruz Basin, where we estimate a crustal thickness of 31.6 ± 1.9 km. The boundary between the upper and lower crust in comparison with the surface of the Moho do not show significant variations other than the depth difference. We observe small crustal variations across the different terranes on the study area, with the thinnest crust located at the Pacific coast and Gulf of Mexico coast. The thickest crust is estimated to be in central Oaxaca and beneath the TMVB.

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Section: Moho Discontinuitymentioning

confidence: 46%

“…Bold grey line shows the MT profile from Arzate-Flores et al (2016). Bottom panel: resistivity model along the magnetotelluric profile modified fromArzate-Flores et al (2016). Dashed white line delineates the crustal thickness proposed in this study along the same profile.…”

mentioning

confidence: 96%

Crustal structure variations in south-central Mexico from receiver functions

Rodríguez-Domínguez

Pérez‐Campos

Montealegre-Cázares

et al. 2019

Geophysical Journal International

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“…We did not solve for source locations of SSEs along the plate interface, as a catalog of SSEs in Oaxaca was recently compiled (53) utilizing the same cGPS stations. To better interpret the seismicity and GPS motions, we also reexamined the configuration of the northern boundary of the Xolapa terrane based on the extent of the core complex (36), aeromagnetic data (20), and topographic information (22). See SI Appendix, sections S1-S3 for a more detailed discussion of the methods used in this study.…”

Section: Methodsmentioning

confidence: 99%

“…Zones of high conductivity near the coast (Fig. 1B) suggest that fluids are released from the slab updip of the USL (21,22) which could impact the occurrence of seismicity. In Oaxaca, Colella et al (46) suggest that trapped fluids in the lowpermeability seal along the plate interface (47-49) may be released by SSEs which then flow upward along the plate interface generating seismicity, as a swarm of earthquakes was found to correspond to an SSE.…”

Section: Significancementioning

confidence: 99%

“…The Xolapa terrane consists of undeformed plutonic intrusions and the highly deformed Xolapa Metamorphic Complex, which by some has been proposed to be of accretionary origin (35,36). Some studies have proposed that faults and shear zones occur along portions of the northern boundary of the Xolapa terrane (22,35,(37)(38)(39). In fact, an interesting characteristic of slip has been observed in the Mexican subduction zone, where coastal GPS sites have shown a small but significant along-strike motion during the trenchward…”

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confidence: 99%

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Earthquake swarms and slow slip on a sliver fault in the Mexican subduction zone

Fasola

Brudzinski

Holtkamp

et al. 2019

Proc. Natl. Acad. Sci. U.S.A.

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The Mexican subduction zone is an ideal location for studying subduction processes due to the short trench-to-coast distances that bring broad portions of the seismogenic and transition zones of the plate interface inland. Using a recently generated seismicity catalog from a local network in Oaxaca, we identified 20 swarms of earthquakes (M < 5) from 2006 to 2012. Swarms outline what appears to be a steeply dipping structure in the overriding plate, indicative of an origin other than the plate interface. This steeply dipping structure corresponds to the northern boundary of the Xolapa terrane. In addition, we observed an interesting characteristic of slow slip events (SSEs) where they showed a shift from trenchward motion toward an along-strike direction at coastal GPS sites. A majority of the swarms were found to correspond in time to the along-strike shift. We propose that swarms and SSEs are occurring on a sliver fault that allows the oblique convergence to be partitioned into trench-perpendicular motion on the subduction interface and trench-parallel motion on the sliver fault. The resistivity structure surrounding the sliver fault suggests that SSEs and swarms of earthquakes occur due to high fluid content in the fault zone. We propose that the sliver fault provides a natural pathway for buoyant fluids attempting to migrate upward after being released from the downgoing plate. Thus, sliver faults could be responsible for the downdip end of the seismogenic zone by creating drier conditions on the subduction interface trenchward of the sliver fault, promoting fast-slip seismogenic rupture behavior.

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Short-Term Interaction between Silent and Devastating Earthquakes in Mexico

Cruz‐Atienza

Tago

Villafuerte

et al. 2020

Preprint

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Triggering of large earthquakes on a fault that hosts aseismic slip or, conversely, triggering of slow slip events (SSE) by passing seismic waves involves seismological questions with major hazard implications. Just a few observations plausibly suggest that such interactions actually happen in nature. In this study we show that three recent devastating earthquakes in Mexico are likely related to SSEs, describing a cascade of events interacting with each other on a regional scale via quasistatic and/or dynamic perturbations. Such interaction seems to be conditioned by the transient memory of Earth materials subject to the "traumatic" stressing produced by the seismic waves of the great Mw8.2 Tehuantepec earthquake, which strongly disturbed the aseismic beating over a 650 km long segment of the subduction plate interface. Our results imply that seismic hazard in large populated areas is a short-term evolving function of seismotectonic processes that are often observable.

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Low Angle Contact Between the Oaxaca and Juárez Terranes Deduced From Magnetotelluric Data

Cited by 4 publications

References 42 publications

Crustal structure variations in south-central Mexico from receiver functions

Crustal structure variations in south-central Mexico from receiver functions

Earthquake swarms and slow slip on a sliver fault in the Mexican subduction zone

Short-Term Interaction between Silent and Devastating Earthquakes in Mexico

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