Papers by DAVID ESCOBEDO ZENIL
Geofísica internacional, Jun 21, 2024
Geofísica Internacional (2024) 63-3: 949-958 A portion of the west of Mexico City is densely popu... more Geofísica Internacional (2024) 63-3: 949-958 A portion of the west of Mexico City is densely populated in an abrupt topography, whose volcanosedimentary materials increase the likelihood of landslides. We exploited the geometry of a quadrangular geophones array to apply Seismic Refraction Tomography (SRT) and Ambient Noise Tomography (ANT) methods and explore the extent of landslide-prone materials. The results show low-velocity areas (Vs < 100 m/s, being Vs group velocities) associated with materials that have lost their resistance due to the increase in pore pressure and the places where eventually, more landslides will occur (120 < Vs < 200 m/s) if mitigation work is not carried out. The most stable zones correspond to materials with velocity values greater than 250 m/s that overlap a bedrock at an average depth of 8 m. Thus, when it is not advisable to perform active source experiments, ANT can provide practical results to determine the extension of the sliding materials. Una porción del poniente de la Ciudad de México está densamente poblada en una topografía abrupta. Los materiales en esa zona son volcano-sedimentarios, los cuales, debido a procesos naturales y antropogénicos, aumentan la probabilidad de deslizamientos de tierra. En este estudio explotamos la geometría de un arreglo cuadrangular de geófonos mediante los métodos de Tomografía de Refracción Sísmica (TRS) y Tomografía de Ruido Ambiental (TRA) para explorar la extensión de los materiales propensos a deslizamientos de tierra. Los resultados muestran áreas de baja velocidad (Vs < 100 m/s) asociadas con materiales que han perdido su resistencia debido al aumento de la presión de poro, y áreas donde eventualmente ocurrirán más deslizamientos de tierra (120 < Vs < 200 m/s) si no se realizan trabajos de mitigación. Las zonas más estables corresponden a materiales con valores de velocidad superiores a 250 m/s que sobreyacen a un subestrato irregular con profundidad media de 8 m. Por lo tanto, cuando no es aconsejable realizar experimentos de fuente activa, TRA puede proporcionar resultados prácticos para determinar la extensión de los materiales propensos a deslizamiento.
Revista geofísica, Dec 22, 2022
Este es un artículo de acceso abierto bajo la licencia CC BY-NC-SA 4.0
September 19, 2017 earthquake considerably affected the southern area of Mexico City; specically,... more September 19, 2017 earthquake considerably affected the southern area of Mexico City; specically, in the transition zone, some local subsidence problems were accentuated. This site is associated wi...
Revista Geofísica
El municipio de Concepción Buenavista se localiza en la Mixteca alta del estado de Oaxaca, México... more El municipio de Concepción Buenavista se localiza en la Mixteca alta del estado de Oaxaca, México. Su población sufre escasez de agua debido al clima semiseco y a la limitada escorrentía superficial en la región. A fin de proponer alternativas de solución al problema de desabasto de agua, se realizó un estudio geológico-geofísico para determinar el sitio más adecuado para la perforación de un pozo que proporcione un caudal de 2 l/s, cantidad de agua necesaria para satisfacer las necesidades de la población. Los resultados permiten determinar un sitio que cumple las condiciones naturales favorables. El sitio se caracteriza por la infiltración del agua superficial que proviene de un arroyo y de la recarga asociada al agua de lluvia.
Natural Hazards
Structural failure due to local soil subsidence is a severe issue in the urban environment, parti... more Structural failure due to local soil subsidence is a severe issue in the urban environment, particularly in cities located on thick sediments. We present such a case from Mexico City, where the near-surface soil characteristics beneath a subsided building were examined using 3D ambient noise tomography. We acquired data using dense arrays of 4.5 Hz vertical geophones placed around the building in two geometries. We performed cross-correlation analyses for 12 central frequencies in the range of 4–12 Hz to built tomographic images of surface wave group velocity. The results indicated a low-velocity layer (~ 120 m/s) for the first 10 m depth which we interpret as the typical clay layer of the Lake Zone of the city. Below, a more complex stiff layer (~ 500 m/s) appeared with significant lateral variations. In another independent analysis of HVSR, we observed that the site period varied between 0.4 and 0.55 s, which further signify the complexity of the subsurface. Thus, the conspicuous structural failure was due to the lack of stiffness of the shallow foundation, which subjected to differential motions between consistent materials from the foot of Chapultepec hill, and the soft lacustrine clays of the Lake Zone. As shown in this case, the seismic response variations in short distances, and short periods, for near-source events could be of great importance as demonstrated in Mexico City during the recent Puebla-Morelos Earthquake (M7.1) of September 19th, 2017.
83rd EAGE Annual Conference & Exhibition
A portion of the west of Mexico City is a densely populated area located in an abrupt topography,... more A portion of the west of Mexico City is a densely populated area located in an abrupt topography, whose volcano-sedimentary materials increase the likelihood of landslides. This study uses Seismic Refraction Tomography (SRT) and Ambient Noise Tomography (ANT) methods to estimate the extent of landslide-prone materials at a test site. We exploited the geometry of a quadrangular array of surface sources and receivers to generate a Vp tomography image of the bedrock and surface-wave group-velocity tomographies of SRTand ANT in the frequency range of 6 to 26 Hz. We found that the best velocities correlation between the two methods is an average frequency of 24 Hz. The results show the areas of low velocity associated with materials that have lost their resistance due to the increase in pore pressure (Vs &lt; 100 m/s) and the areas where eventually more landslides will occur (120 &lt; Vs &lt; 200 m/s) if mitigation work is not carried out. The most stable zones correspond to materials with velocity values greater than 250 m/s that overlap a substratum at an average depth of 8 m. In the case of a high risk of landslide, when it is not advisable to perform active source experiments, ANT can provide good results to determine the extension of the sliding materials.
Near Surface Geophysics, 2020
ABSTRACTAn unexpected surface subsidence in Mexico City on 19 May 2015 prompted a detailed geophy... more ABSTRACTAn unexpected surface subsidence in Mexico City on 19 May 2015 prompted a detailed geophysical investigation of the three‐dimensional structure of a collapsed‐soil mine located in a section of the Chapultepec Park in the vicinity of an artificial lake. As revealed from past geological explorations, the subsoil at the site consists of volcano‐sedimentary materials that were quarried in the mid‐20th century; subsequently, during the construction of the park, most of those mines had been only partially rehabilitated, with a potential risk of land subsidence. Near‐surface imaging techniques based on ambient seismic noise as well as microgravimetry, electrical resistivity tomography, shallow seismic refraction methods were evaluated for their applicability to characterize the structure of the collapsed mine. Tomography images computed using ambient‐noise array data characterized the extent of the underground mine showing high‐velocity anomaly, while results from microgravimetry a...
September 19, 2017 earthquake considerably affected the southern area of Mexico City; specically,... more September 19, 2017 earthquake considerably affected the southern area of Mexico City; specically, in the transition zone, some local subsidence problems were accentuated. This site is associated wi...
Ingeniería Investigación y Tecnología, 2021
To explore the usefulness of the ambient seismic noise tomography method for characterizing the s... more To explore the usefulness of the ambient seismic noise tomography method for characterizing the subsoil surface structure, in this study, we apply this method to contribute to geotechnical decision-making in the construction of a school building. We used a rectangular array (36 x 56 m) of 48-4.5 Hz vertical geophones and produce surface wave tomographies from the travel times of Rayleigh waves extracted by cross-correlation of seismic noise. We determined a final 3D Vs model using 1D models derived from the inversion of dispersion curves obtained from the tomography maps for different frequencies. The 3D model shows an excellent resolution (vertical and lateral); we observe critical velocity contrasts in the range of 2 to 15 m deep. At depths higher than 15 m, the velocity has values close to 900 m/s; however, we observe a low-velocity anomaly associated with a lava tube or crack that seems to continue under an adjacent building.
In order to provide elements for geotechnical decisions in the construction of a school building,... more In order to provide elements for geotechnical decisions in the construction of a school building, we explored the subsoil structure through a 3D velocity model built by ambient seismic noise techniques. First, working with noise cross-correlations, we built a 3D-Vs structure using 1D-Vs models derived from the inversion of dispersion curves extracted from the tomography maps for several frequencies. Second, we validated this model with the results from the joint inversion of dispersion curves estimated from the SPAC and the HVSR functions. The 3D model shows an excellent resolution (vertical and lateral). The bedrock could be observed in depths higher than 12 m. The model gave us evidence of a low-velocity anomaly associated with a lava tube or crack that penetrates under an adjacent building.
Symposium on the Application of Geophysics to Engineering and Environmental Problems 2019, 2019
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Papers by DAVID ESCOBEDO ZENIL