Geofisica Internacional 

About: Geofisica Internacional is an academic journal published by National Autonomous University of Mexico. The journal publishes majorly in the area(s): Volcano & Subduction. It has an ISSN identifier of 0016-7169. It is also open access. Over the lifetime, 1283 publications have been published receiving 12551 citations.

Impact of El Niño on precipitation in Mexico

Abstract: ENSO is capable of affecting normal climatic patterns around the world. El Nino, and its counterpart, La Nina, modify the normal precipitation patterns in Mexico. In general, during El Nino (La Nina) winters, precipitation increases (decreases) over northwestern Mexico, while it decreases (increases) in the region around the Isthmus of Tehuantepec. A southward shift in the position of the subtropical jet stream increases the number of Northerners over the southern part of the Gulf of Mexico. A summer El Nino causes a deficit in precipitation. Various mechanisms, associated with El Nino, result in negative precipitation anomalies over most of Mexico. Enhanced subsidence associated with a southward shift of the Inter Tropical Convergence Zone (ITZC), more intense trade winds, a decreased number of tropical cyclones over the Intra Americas Seas (IAS) and reduced relative humidity, may result in severe droughts. These elements produced major socioeconomic loses during the summer of 1997 that could be directly related to El Nino. During La Nina years, climate conditions return to normal or result in enhanced precipitation. Current seasonal prediction schemes appear to be skillful enough to provide useful information in the planning of certain socioeconomic activities.

Metamorphic belts of southern Mexico and their tectonic significance

Abstract: Los terrenos cristianos del sur de Mexico son subdivididos en los siguientes complejos: Oaxaqueno (Proterozoico medio), Acatlan (Paleozoico), Xopla y “Tierra caliente” (?Paleozoico? Mesozoico) El primero consiste en gneises bandeados de la faceis de granulita, con una parte basal de ortogneis anortositico gabroide y una parte superior de paragneises calcareos, peliticos y cuarzo-feldespaticos, que incluyen varios intervalos de charnockita. La edad, deformacion, estratigrafia y metamorfismo del complejo Oaxaqueno son interpretados en terminos de un clico tectonico grenvillano. El complejo Acatlan polimetam´rfico cosnste en dos partes: (1) una placa parautoctona formada por migmatita en la base, esquistos peliticos y psamiticos con gabos diferenciados en la parte media, y metasedimentos cuarzosos sin carbonatos en la parte superior (2) Una placa al´ctona formada por rocas ofioliticas eclogitizadas, junto con abundantes granitoides milonitizados, todo ellos cubierto pot metasedimentos flyschoides e inmaduros. El complejo Acatlan se interpreta en terminos de un cliclo Wilson del Paleozoico, relacionado con la apertura y cierre de un oceano pre- Atlantico, mejor conocido comolapetus en el sistema orogenico Apalachiano-Caledoniano. Los complejos metamorficos Xopala y "Tieera caliente", de edad probablemente mesozoica, parecen representar respectivamente las partes infracortical (rais) y supracortical de arcos magmaticos y cuencas sedimentarias asociadas, que se desarrollaron en respuesta a una subduccion pacific principalmente durante la fase mesozioca del regimen tectonico Cordillerano. LA construccion geoligica gradual del sur de Mexico se atribuye asi a los regimenes tectonicos Grenvilliano, Apalachiano y Cordillerano, cada uno de los cuales dejo su rubrica en las rocas descritas prevemente en este trabajo

Geological and geochemical investigations on the eastern trans mexican volcanic belt.

Abstract: This paper reports upon geological and geochemical investigations of the easternmost extension of the Trans Mexican Volcanic Belt (TMVB). As a result of our work we prefer to consider that the TMVB terminates at the Gulf coast and not in the Altiplano area (e.g. Robin, 1981), with respect to a Pliocene-Quaternary volcanic activity. During that time the volcanism is of calcalkaline and alkaline character. The older volcanic activity, e.g. of Miocene times, produced alkaline-calcalkaline igneous rocks in the Massif de Palma Sola and calcalkaline igneous rocks in the western part of Mexico due to the eastwest migration of the subduction of the Palaeopacific plate (Robin, 1976). Our geochemical results neither deny nor favour one single geological model and do not even exclude the microplate version of Shurbet and Cebull (1984). However, the geochemical data cannot be explained by direct derivation of the volcanics from the oceanic lithosphere (e.g. Robin, 1981, 1982). Irrespective of this fact, the volcanism of the TMVB suggests to be caused or induced by the subduction of the Rivera and Cocos plate association.

A compilation of location, size, and geomorphological parameters of volcanoes of the Michoacan-Guanajuato volcanic field, central Mexico.

Abstract: Se han catalogado mas de mil centros volcanicos en el campo volcanico Michoacan-Guanajuato, el cual esta situado en la parte media del Cinturon Volcanico Mexicano. Los volcanes catalogados incluyen: 901 conos cineriticos o cupulas de lava, 43 domos, 22 maars o cercos anulares de tobas, 13 volcanes de tipo escudo con conos en las cimas y 61 flujos de lava no asociados a conos. Estos volcanes se distribuyen entre los 200 km y 430 km medidos desde la Fosa Americana Mediana. No se observa alineamiento preferencial, sin embargo, la concentracion maxima estimada se encuentra a los 250 km. Entre los indicadores morfologicos catalogicos catalogados para determinar la edad de los conos cineriticos, la densidad de las zanjas y la clasificacion geomorfologica de los flujos de lava resultaron sensibles dentro del limite de determinacion de edad mediante 14 C. Finalmente, se clasificaron 78 volcanes como morfologicamente jovenes, de edad de 40,000 anos o menos y un volumen de 31 km 3 , cifras que indican una tasa estimada en el volumen de erupcion de 0.8 km 3 /1 000 anos pare todo el campo volcanico en su conjunto.

Airborne and Ground-Based lidar measurements of the El Chichón stratospheric aerosol from 90°N to 56°S

Abstract: This paper presents the results of number of airborne lidar campaigns, covering latitudes from 90°N to 56°S over the period July 1982 to January 1984. These flights were designed to determine key characteristics of the stratospheric aerosol produced from March-April 1982 eruptions of El Chichon. Also discussed is the 1o years ground based lidar data set at NASA Langley (37°). Backscatter ratios, integrated aerosol backscatter functions, column mass densities, and mass of the stratospheric aerosol versus latitude and, where appropriate, altitude are described. Two general stratospheric-layer regions are shown to exist initially after the eruption, one above 20 km and one below 20 km. the material below about 20 km moved to higher latitudes, followed by the material above 20 km which for the most part, was constrained to an equatorial to an equatorial belt between about 10°S and 30°N for approximately 6 months. In the early fall of 1982, the total global stratospheric increase due to El Chichon was estimated to be 12 megatonnes. The maximum global impact is thought to have occurred between the July and October 1982 missions. Maximum stratospheric effects at 37°N were experienced in January 1983. The maximum column density was seen to move north in time. The altitude of the peak of stratospheric material moved downward and the layer broadened in width as material aged.