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A seismic network for the valley of Mexico: present status and perspectives

VICTOR HUGO ESPINDOLA CASTRO (2018)

Valley of Mexico (VM) Seismic Network-Red Sísmica del Valle de México (RSVM) is a regional digital network deployed by Instituto de Geofísica, Universidad Nacional Autónoma de México (UNAM). It started at 1996 with some vertical shortperiod instruments scattered across the valley, which since 2006 were gradually replaced by three-component intermediate, broadband, and more recently accelerographic instruments. It presently counts 28 stations, representing a contribution to the new generation of regional seismic networks in Mexico with the goal of densifying the coverage throughout the known seismic zones in the country. Along 11 yrs of operation with threecomponent sensors, this network has recorded numerous local and regional earthquakes. Seismicity recorded by RSVM has illuminated major seismic areas inside the valley and the style of faulting of this activity, having for the first time a focal mechanism catalog of this zone of the country. The recent upgrading of 16 out of 31 stations with accelerometers has provided, in real time, the strong ground motion in Mexico City generated by great earthquakes (M > 7) that occurred outside of the valley, having important implications to civil protection purposes. The results obtained up to now highlight the need to complete the upgrade of the rest of the stations, as well as densifying the network to deepen our knowledge of the structure of VM. © Copyright 2018 Seismological Society of America.

Article

REDES DE COMUNICACIÓN SISMOLOGÍA RED SISMICA - VALLE DE MÉXICO SEISMOLOGY Seismic Network CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA CIENCIAS DE LA TIERRA Y DEL ESPACIO GEOFÍSICA SISMOLOGÍA Y PROSPECCIÓN SÍSMICA Seismology concept8601

The mexican national seismological service: an overview

XYOLI PEREZ CAMPOS (2018)

The Servicio Sismológico Nacional (SSN, Mexican National Seismological Service) has a history of 107 yrs. In the last 13 yrs, the SSN has gone through a significant modernization process, involving the installation of new broadband stations with colocalized accelerometers, seismometers, and Global Positioning System (GPS) receivers. New collaborations with other Mexican regional networks helped increase the number of stations from which the SSN receives data. In this article, we present the current backbone broadband network configuration; data flow from the stations to the automatic and manual publication of the earthquake location and magnitude; and the seismic catalog, which includes more than 105,000 events since 1900. A clear example of the successful performance of this network is the recording of the 8 September 2017 Mw 8.2 earthquake, located in the Gulf of Tehuantepec. We present the signals of 52 of the 63 SSN broadband stations that recorded the event in real time. This earthquake represents the largest recorded in Mexico by a comprehensive national network. © Copyright 2018 Seismological Society of America.

Article

REDE DE BANDA ANCHA GEOFÍSICA SISTEMA DE POSICIONAMIENTO GLOBAL ALCANTARILLADO SANITARIO SISMOLOGÍA Broadband networks Geophysics Global positioning system Sanitary sewer concept8601 Seismology CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA CIENCIAS DE LA TIERRA Y DEL ESPACIO GEOFÍSICA SISMOLOGÍA Y PROSPECCIÓN SÍSMICA

TRANSIENT ELECTROMAGNETIC RESPONSE OF A CONDUCTING INFINITE CYLINDER EMBEDDEN IN A CONDUCTING MEDIUM

Shri Krishna Singh (1972)

Transient electromagnetic response of a conducting permeable cylinder embedded in a conducting infinite space is obtained in the form of definite integrals. The source is an infinite insulated cable which ties outside the cylinder and carries a Heaviside current. The displacement currents have been neglected. Expression for transient response function under quasi-static approximation is also given.

Article

Transient Electromagnetic Response Conducting Cylinder Transient Electromagnetic Response Conducting Cylinder Seismology concept8601 Seismology CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA CIENCIAS DE LA TIERRA Y DEL ESPACIO GEOFÍSICA SISMOLOGÍA Y PROSPECCIÓN SÍSMICA

Interaction of Cocos and rivera plates with the upper-mantle transition zone underneath central Mexico.

XYOLI PEREZ CAMPOS (2014)

Receiver functions (RFs) from 224 permanent and temporary stations in central and southern Mexico were used to characterize the upper-mantle transition zone in that region. Discontinuities at 410 and 660 km depth are both deeper compared to iasp91, which reflects a slow velocity anomaly in the upper mantle. They show topography on the interfaces that is consistent with the interaction of the subducted slab or its broken off extension. A low-velocity layer on top of the 410 is identified mainly on the continental side of where the slab pierces it (i.e. in the lee of the slab roll-back). In general the RFs show a complex behaviour where the mantle has been disturbed by the lateral motion of the subducted slab, and are simple where it has not. Complexity on the 660 coincides with the place where the broken off portion of the Farallon Plate would have penetrated this interface or is possibly lying on top of it.

Article

MANTO DE PROCESOS TRANSICIONES DE FASE NORTEAMÉRICA Volcanic Belt Shallow earthquakes Waves Seismology concept8601 CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA CIENCIAS DE LA TIERRA Y DEL ESPACIO GEOFÍSICA SISMOLOGÍA Y PROSPECCIÓN SÍSMICA

Moment Tensor Catalog for Mexican Earthquakes: Almost Two Decades of Seismicity

Sara Franco (2020)

In this work we used waveforms and the catalog of National Seismological Service(SSN) to analyze more than 20,000 events with M>= 4.0 for the period2000-2018 with the goal of determining their moment tensor solutions. Because oflarge number of events, we automatize the process based on a set criteria. Usingepicentral location and magnitude of each earthquake reported by the SSN, a setof valid stations to be used for the moment solution, the length of time series,and the filter band for data and synthetics are automatically selected. Toexpedite calculations a pre-computed library of Green functions is used.

Through a linear inversion, for three-station combinations, the observed data andthe corresponding Green functions are used to determine the seismic momenttensor (with null isotropic component). To reduce a possible bias related to thestation distribution, each solution is weightened as a function of the azimuthalcoverage of the stations used. After the automatic process solutions of only8,000 earthquakes could be obtained; other events were rejected because ofincomplete length of the data segment and/or its integrity.

The solution quality is measured by the variance reduction value (VR). Astatistical analysis of quality allows us to establish a VR value of ≥ 50% asreasonable threshold for reliable solutions. With these criteria a catalog of ~1,500 events have been compiled, including some small events (Mw < 4.0).

There is evidence that show that the location of the well-solved events matchesthe areas of higher density of seismologic stations, and the limits of tectonicplates as well. A comparison between the catalog here obtained and the GlobalCentroid Moment Tensor (GCMT) catalog shows similarities. However, the magnitudereported in our catalog is systematically smaller than those reported byGCMT.

The moment tensor solution catalog is available online in a public database(132.248.6.13/~cmt). This work is the first in Mexico in which a database ofthis kind is presented.

Article

Moment Tensor Catalog Mexican Earthquakes Seismicity Moment Tensor Catalog Mexican Earthquakes Seismology concept8601 Seismology CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA CIENCIAS DE LA TIERRA Y DEL ESPACIO GEOFÍSICA SISMOLOGÍA Y PROSPECCIÓN SÍSMICA

PREMONITORY ELEVATION CHANGE BEFORE AN EARTHQUAKE BASED ON DILATANCY-DIFFUSION MODEL

Shri Krishna Singh (1973)

The dilatancy-diffusion model, recently proposed to explain premonitory changes in geo-physical and geochemical fields before several shallow earthquakes, implies uplift of the epicentral region. Based on a dilating sphere in an elastic half-space, simple formulas and a graph are presented which could be used to predict the magnitude and depth of the focus of a future earthquake if the magnitude of the dilatancy were known. Alternatively an estímate of the magnitude of the dilatancy can be made with the help of the graph by compiling information on maximum vertical displacement, depth of the center and the radius of the dilating sphere for earthquakes that are preceded by dilatancy.

Article

Premonitory Elevation Change Earthquake Dilatancy-Diffusion Model Premonitory Elevation Change Earthquake Dilatancy-Diffusion Model Seismology concept8601 Seismology CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA CIENCIAS DE LA TIERRA Y DEL ESPACIO GEOFÍSICA SISMOLOGÍA Y PROSPECCIÓN SÍSMICA

Modelado en tres dimensiones de datos gravimétricos y aeromagnéticos del campo volcánico Los Tuxtlas, Veracruz, México

Three-dimensional modelling of gravity and aeromagnetic data from Los Tuxtlas volcanic field, Veracruz, Mexico

Rodrigo Pérez Luján (2021)

El Campo Volcánico Los Tuxtlas (CVLT), enclavado sobre la planicie costera del Golfo de México al sur del estado de Veracruz, está constituido por cuatro edificios volcánicos de composición mayormente alcalina: San Martín Tuxtla (SMT), San Martín Pajapan (SMP), Santa Marta (SM) y el Cerro El Vigía (CEV), además de numerosos conos de escoria y mares. La datación de las rocas volcánicas del campo ha permitido inferir que la actividad volcánica en esta región inició hace aproximadamente 7 Ma. Y la última erupción reportada fue la del volcán SMT en 1793. El campo volcánico está limitado hacia el norte por el Golfo de México, al este por la Cuenca Salina del Istmo y al oeste y sur por la Cuenca de Veracruz. Esta última se ha clasificado como cuenca de antepaís, en la cual se depositaron secuencias sedimentarias del Jurásico al Cuaternario. Se infirió la estructura cortical en esta región mediante la modelación inversa lineal de datos gravimétricos y aeromagnéticos. El modelo de densidades obtenido sugiere que las cuencas sedimentarias que rodean al campo volcánico alcanzan una profundidad de al menos 8 km en su zona más profunda, muestran continuidad hacia la región marina y presentan una disminución de espesor hacia el suroeste y sureste. Asimismo, el modelo de densidades muestra cuerpos anómalos (~2.76 𝑔 𝑐𝑚3 ⁄ ) subyaciendo las zonas central y oriental del campo. El modelo magnético muestra la presencia de un cuerpo con alta susceptibilidad magnética (0.023 a 0.1 SI) y de gran volumen que se extiende hasta un profundidad de entre 10 y 15 km bajo los volcanes SM y SMP, así como una estructura estrecha y alargada en una dirección coincidente con el sistema de fracturas con rumbo NW-SE en la zona central del campo, lo cual sugiere la presencia de un vulcanismo fisural asociado a la distribución lineal de conos de escoria encontrados en el área. Al occidente, se encontraron regiones de menor volumen y susceptibilidad magnética (0.023 a 0.05 SI) bajo el CEV, así como una región magnetizada, aplanada y somera al noroeste del Vigía, donde la topografía muestra pocos rasgos prominentes. Resalta la ausencia de cuerpos intensamente magnetizados bajo el volcán SMT y los numerosos aparatos volcánicos situados sobre sus pendientes.

The Los Tuxtlas Volcanic Field (LTVF), located on the coastal plains of the Gulf of Mexico in southern Veracruz State, México, is made up of four volcanic edifices of mostly alkaline composition: San Martín Tuxtla (SMT), San Martín Pajapan (SMP), Santa Marta (SM) and the Cerro El Vigía (CEV), in addition to numerous cinder cones and maars. Dating of the volcanic rocks of this field has allowed to infer that the volcanic activity in this region began nearly 7 Ma. The last eruption being that of the SMT volcano in 1793. To the north, the LTVF is bounded by the Gulf of México, to the east by the Salina del Istmo Basin and to the west and south by the Veracruz Basin. The latter has been classified as a foreland basin in which sedimentary sequences from Jurassic to Quaternary were deposited. We inferred the crustal structure in this region from the inverse modelling of gravity and aeromagnetic data. The obtained density model suggests that the sedimentary basins that surround the volcanic field reach a depth of at least 8 km in their deepest zones, as well as anomalous bodies (~2.76 𝑔 𝑐𝑚3 ⁄ ) underlying the central and eastern zones of the LTVF. The obtained magnetic model shows the presence of a high magnetic susceptibility (0.023 to 0.1 SI) and voluminous structure that extends up to between 10 and 15 km in depth beneath SM and SMP volcanoes, in addition to an elongated one aligned with the NW-SE fracture zone in central LTVF, this suggests the presence of fissure volcanism associated with the linear cinder cone distribution in the area. In the western part of the field, we found structures with lower magnetic susceptibilities (0.023 to 0.05 SI) and less voluminous in comparison to the eastern bodies; a sphere-like body underlying the CEV volcano, as well as a shallow, flattened region to the northwest of the CEV, where topography shows very few prominent features. Highlights the absence of intensely magnetized bodies beneath SMT volcano and the numerous volcanic formations situated on its slopes.

Master thesis

gravimetría, magnetometría, modelado inverso 3D, Campo Volcánico Los Tuxtlas, Cuenca Sedimentaria Veracruz gravity, magnetics, 3D inverse modelling, Los Tuxtlas Volcanic Field, Veracruz Sedimentary Basin CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA CIENCIAS DE LA TIERRA Y DEL ESPACIO GEOFÍSICA GRAVEDAD (TERRESTRE) Y PROSPECCIÓN GRAVIMÉTRICA GRAVEDAD (TERRESTRE) Y PROSPECCIÓN GRAVIMÉTRICA

Métodos de análisis de vulnerabilidad a la licuación en suelos

GIOVANNI ALEJANDRO QUINTOS LIMA (2020)

"Se ha propuesto como objetivo general de esta investigación realizar un análisis detallado de las metodologías aplicadas en la práctica profesional y las recomendaciones más recientemente publicadas. Para cada metodología, se ha hecho un análisis paramétrico de los factores que intervienen en los procesos, estableciendo aquellos de mayor importancia. También se han incluido los procedimientos para la evaluación de deformaciones asociadas con el fenómeno. Adicionalmente, a partir de pruebas geotécnicas y geofísicas ejecutadas en sitios dentro del territorio mexicano, se ha hecho un análisis de la vulnerabilidad a la licuación y de las deformaciones verticales y laterales generadas, aplicando las diferentes metodologías, mostrando las ventajas y desventajas entre los resultados obtenidos".

Master thesis

Mecánica de suelos Ingeniería estructural Sedimentos (Geología) Estratigrafía Ingeniería sísmica Geofísica Geotécnica INGENIERÍA Y TECNOLOGÍA

Sismograma de la estación Santa Fe

Servicio Sismológico Nacional (IGEF-UNAM) (2012)

Entrada mayo 11, 2012 at 11:21 a.m. (GMT) / Salida mayo 12, 2012 at 11:21 a.m. (GMT)

Presenta registro de movimiento sísmico.

Estación telemática que envía su señal a la estación central localizada en el Instituto de Geofísica de la UNAM y pertenece a la red sismológica convencional.

Componente Z.

Event

Sismología Sismología Sismología CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA CIENCIAS DE LA TIERRA Y DEL ESPACIO GEOFÍSICA SISMOLOGÍA Y PROSPECCIÓN SÍSMICA

Sismograma de la estación Santa Fe

Servicio Sismológico Nacional (IGEF-UNAM) (2013)

Entrada febrero 10, 2013 at 14:12 p.m. (GMT) / Salida febrero 11, 2013 at 13:06 p.m. (GMT)

Presenta registro sísmico.

Estación telemática que envia su señal en tiempo real directamente a la estación central localizada en el Instituto de Geofísica de la UNAM y pertenece a la red sismológica convencional.

Componente Z.

Event

Sismología Sismología Sismología CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA CIENCIAS DE LA TIERRA Y DEL ESPACIO GEOFÍSICA SISMOLOGÍA Y PROSPECCIÓN SÍSMICA