A Report on the Atoyac, Mexico, Earthquake of 13 April 2007 (Mw 5.9)

Singh, S. K.; Ordaz, Mario; Pacheco, J. F.; Alcántara, L.; Iglesias, A.; Alcocer, Sergio M.; García, David Álvarez; Pérez‐Campos, Xyoli; Valdés, Carlos; Almora, D.; Aguilar, Luis; Ambriz, M.; Anderson, John G.; Ayala, M.; Cárdenas, Carlos; Castro, Gerardo; Cruz, Juan Carlos; Delgado, R.; Domínguez, L. A.; Estrada, Jorge Arrese; Franco, Sara; Flores, L; Gutiérrez, Carlos A. Mortera; Macias, Miguel; Molina, Indira; Morquecho, C.; Ortiz, John P.; Pacheco-Martínez, M. A.; Quezada, A.; Quaas, R.; Quintanar, Luis; Pérez, Cirilo; Pérez, Jorge Luis Tórtora; Ruiz, A. L.; Sandoval, H.; Torres, Marta E; Vázquez, R.; Velasco, Juan Manuel Burgos; Velazquez, J. C. Jimenez; Velázquez, M.

doi:10.1785/gssrl.78.6.635

Cited by 11 publications

(8 citation statements)

References 24 publications

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“…Based on the focal mechanism, these events were grouped as intraslab and interplate earthquakes. Steeply dipping thrust events, which occur in the subducted plate near the coast (Singh et al 2007, Pacheco andSingh 2010) were grouped with the 1 and 2 and additional ten earthquakes which were recorded both at CU and SCT (see text).…”

Section: Data and Analysis Cu A Hill-zone Sitementioning

confidence: 99%

Intraslab versus Interplate Earthquakes as Recorded in Mexico City: Implications for Seismic Hazard

et al. 2015

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We study the relative importance of interplate and intraslab earthquakes in the seismic hazard of Mexico City by analyzing accelerograms recorded at the hill-zone site of CU (1964–2012) and the lake-bed site of SCT (1985–2012). Amax exceeded 6 gal during 20 earthquakes at CU during this period. Of these, eight were intraslab events so that the exceedance rate of Amax ≥ 6 gal from both types of earthquakes is roughly about the same. The estimated return period of Amax of 30 gal from the two types of earthquakes is ∼100 yrs. If we consider high-frequency (2.5–8.5 Hz) acceleration ( AmaxHF) at CU, then the top 7 out of the 20 events are all intraslab earthquakes. Even at the lake-bed site of SCT, the AmaxHF values are, generally, associated with intraslab earthquakes. It follows that the risk from both types of earthquakes to low-rise construction in the city needs careful assessment.

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Section: Data and Analysis Cu A Hill-zone Sitementioning

confidence: 99%

Intraslab versus Interplate Earthquakes as Recorded in Mexico City: Implications for Seismic Hazard

et al. 2015

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“… b Sources are 1, focal mechanism, M w , and centroid/constraint depth from this study; 2, focal mechanism, M w , and centroid depth from the Global CMT catalog; 3, focal mechanism, M w , and depth from Pacheco and Singh [1998]; and 4, focal mechanism, M w , and depth from Singh et al [2007]. …”

Section: New Seismic Data and Data Processingmentioning

confidence: 99%

“…In the last 15 years, there have been several moderate/large inslab earthquakes in Mexico which were located near the coast, below or close to the downdip edge of the coupled plate interface. The focal mechanisms of some of these events exhibit downdip extension (e.g., Michoacan earthquake of 11 January 1997, M w 7.1 [ Santoyo et al , 2005]; Oaxaca earthquake of 30 September 1999, M w 7.4 [ Singh et al , 2000b]), while others indicate downdip compression (e.g., Atoyac earthquake of 13 April 2007, M w 5.9 [ Singh et al , 2007]). Is the occurrence of these earthquakes in agreement with the state of stress in Guerrero deduced from small earthquakes?…”

Section: Introductionmentioning

confidence: 99%

Seismicity and state of stress in Guerrero segment of the Mexican subduction zone

2010

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[1] We take advantage of a relatively dense network of seismic stations in the Guerrero segment of the Mexican subduction zone to study seismicity and state of stress in the region. We combine our results with recent observations on the geometry of the subducted Cocos plate imaged from receiver function (RF) analysis, an ultraslow velocity layer mapped in the upper crust of the subducted slab, and episodic slow slip events (SSEs) and nonvolcanic tremors (NVTs) reported in the region to obtain a comprehensive view of the subduction process. Seismicity and focal mechanisms confirm subduction of the Cocos plate below Mexico at a shallow angle, reaching a depth of 25 km at a distance of 65 km from the trench. The plate begins to unbend at this distance and becomes horizontal at a distance of $120 km at a depth of 40 km. Some of the highlights of the inslab seismicity are as follows: (1) A cluster of earthquakes in the depth range of 25-45 km, immediately downdip from the strongly coupled part of the plate interface, revealing both downdip compressional and extensional events. This seismicity extends from $80 to 105 km from the trench and may be attributed to the unbending of the slab. (2) The slab devoid of seismicity in the distance range of $105-160 km. (3) Sparse inslab seismicity revealing downdip extension in the distance range of 160-240 km. The NVTs are also confined to this distance range. The episodic SSEs occur on the horizontal segment, in the distance range of $105-240 km, where an ultraslow velocity layer in the upper crust of the slab has been mapped from waveform modeling of converted SP phases. Thus, in the distance range of $105-160 km, SSEs occur but NVTs and inslab earthquakes are absent. This suggests that metamorphic dehydration reactions in the subducting oceanic crust and upper mantle begin at a distance of $160 km, giving rise to both the inslab earthquakes and NVTs. No inslab earthquake occurs beyond 240 km. The receiver function images and P wave tomography suggest that the slab begins a steep plunge at a distance of $310 km, reaching a depth of 500 km around 340 km from the trench. The negative buoyancy of such a slab should give rise to large extensional stress in the slab. Yet inslab seismicity is remarkably low, which may be explained by a slab that is not continuous up to a depth of 500 km, but is broken at a shallower depth. The resulting slab window may permit subslab material to flow through the gap. This may provide an explanation for the recent rift-related basalts found near Mexico City. The fore-arc, upper plate seismicity, which during the period of study (1995)(1996)(1997)(1998)(1999)(2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007) consisted of a moderate earthquake (M w 5.8) near the coast (H = 12 km), its numerous aftershocks, and two shallow events farther inland, demonstrates a trench-normal extension in the upper plate near this convergent margin, a state of stress that may be explained by tectonic erosion and/or seaward retreat of the trench. Seismicity, location of the ...

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“…The result presented in Figure 2c shows that while the velocity perturbation related to the SSE affected all of the station subsets and had a North–to–South extension of at least 250 km, it was most pronounced in the northern part of the profile, rather far from the coast. We also observed the velocity change signature of the Atoyac earthquake (Mw 5.9) that occurred on April 14, 2007, a few kilometers off the Pacific coast [ Singh et al , 2007], which was seen as a decrease in the seismic velocity solely in the southern part of the MASE array (Figures 2c and 2d). These data demonstrate that noise‐based measurements can discriminate localized speed variations and thus provide reliable information about the geographical extension of the velocity perturbation associated with the 2006 SSE.…”

mentioning

confidence: 99%

Seismic evidence of nonlinear crustal deformation during a large slow slip event in Mexico

Rivet

Campillo

Shapiro

et al. 2011

Geophys. Res. Lett.

120

106

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5p.International audienceRepeated cross-correlations of ambient seismic noise indicate a long-term seismic velocity change associated with the 2006 M7.5 slow-slip event (SSE) in the Guerrero region, Mexico. Because the SSE does not radiate seismic waves, the measured velocity change cannot be associated with the response of superficial soil layers to strong shaking as observed for regular earthquakes. The perturbation observed maximized at periods between 7 s and 17 s, which correspond to surface waves with sensitivity to the upper and middle crust. The amplitude of the relative velocity change (∼10−3) was much larger than the volumetric deformation (∼10−6) at the depths probed (∼5-20 km). Moreover, the time dependence of the velocity perturbation indicated that it was related to the strain rate rather than the strain itself. This suggests that during strong slow-slip events, the deformation of the overlying crust shows significant nonlinear elastic behavior

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A Report on the Atoyac, Mexico, Earthquake of 13 April 2007 (Mw 5.9)

Cited by 11 publications

References 24 publications

Intraslab versus Interplate Earthquakes as Recorded in Mexico City: Implications for Seismic Hazard

Intraslab versus Interplate Earthquakes as Recorded in Mexico City: Implications for Seismic Hazard

Seismicity and state of stress in Guerrero segment of the Mexican subduction zone

Seismic evidence of nonlinear crustal deformation during a large slow slip event in Mexico

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