Person:
Muñoz Martín, Alfonso

First Name

Alfonso

Last Name

Muñoz Martín

URI

https://hdl.handle.net/20.500.14352/75220

Affiliation

Universidad Complutense de Madrid

Faculty / Institute

Ciencias Geológicas

Department

Geodinámica, Estratigrafía y Paleontología

Area

Geodinámica Interna

Identifiers

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Now showing 1 - 10 of 45

Análisis de nuevos datos gravimétricos marinos en el entorno de la Isla Decepción (Islas Shetland del Sur, Antártida)
(Revista de la Sociedad Geológica de España, 2001) Carbó Gorosabel, Andrés; Muñoz Martín, Alfonso; Martín Dávila, José; Catalán, Manuel; García, Alicia
La Isla Decepción es la parte emergida de un volcán muy joven y activo. Se encuentra situada en el SO del Estrecho de Bransfield, que separa la Península Antártica de las islas Shetland del Sur. En este trabajo se muestran los resultados del levantamiento gravimétrico realizado en la campaña de investigación geofísica marina DECVOL99 (Diciembre de 1999). El procesado de los 4906 datos seleccionados, obtenidos a lo largo de 48 líneas de navegación, ha permitido la realización de dos mapas de anomalías de Bouguer en el interior y en el exterior de la Isla Decepción. El tratamiento de los datos gravimétricos ha incluido, además de las correcciones habituales, la corrección topográfica terrestre y del fondo marino utilizando una malla de 1 km de lado. Los mapas de anomalías de Bouguer resultantes muestran una serie de anomalías y gradientes gravimétricos bien definidos que, al integrarlos con el resto de información existente, permiten su interpretación desde el punto de vista estructural y tectónico. De este modo las anomalías gravimétricas en el entorno de la Isla Decepción se encuentran definidas por una serie de mínimos y máximos con dos orientaciones principales NE-SO y NO-SE, que se corresponden bien con rasgos morfoestructurales y geofísicos en otros sectores del Estrecho de Bransfield. La mayor parte de los gradientes gravimétricos alargados y con carácter neto pueden ser interpretados como zonas de fractura NO-SE y NE-SO que limitan áreas de máximos y mínimos gravimétricos. Las anomalías positivas de gran longitud de onda constituyen la continuación hacia el SO de la corteza continental de la Isla Livingston, mientras que los máximos gravimétricos de alta frecuencia están asociados a bloques elevados y de alta densidad. Las zonas de mínimos valores de anomalía de Bouguer coinciden con los principales ejes de extensión y máximo relleno de materiales sedimentarios recientes. Las orientaciones y localizaciones de las bandas de alto gradiente gravimétrico permiten su correlación con zonas de fracturas definidas mediante otros datos geofísicos marinos, así como con la batimetría y los datos estructurales medidos en superficie.
Estructura alpina del antepaís ibérico
(Geología de España, 2004) Vicente Muñoz, Gerardo de; Muñoz Martín, Alfonso; Guimerà Rosso, Joan; Vegas, Ramón; Cloetingh, Sierd; Vicente Muñoz, Gerardo de
Controles tectónicos y estructurales de la incisión fluvial en el centro-oeste de la Cuenca del Duero, NO de Iberia
(Geogaceta, 2007) Antón López, Loreto; Muñoz Martín, Alfonso
The present work approaches incision rates quantification of Duero River in the central- west par t of Iberia and implications of tectonics in the evolution and change of drainage patterns. For this aim we calculate incision rates from the two main geomorphological surfaces defined in the area. Comparing fluvial incision rates and fracture pattern a strong structural control is shown; either in the orientation of drainage network, either in the incision rates distribution. Drainage pattern shows two main orientations, NW-SE following the hercinian structure of the area and NE-SW to N-S matching with the main fracture sets (Duero, Almendra, Almeida-Valderaduey faults, as example). Fluvial incision is mostly controlled by the great faults and faults systems NE-SW to N-S oriented.
Survey explores active tectonics in Northeastern Caribbean
(Eos, Transactions American Geophysical Union, 2005) Carbó Gorosabel, Andrés; Córdoba Barba, Diego; Martín Dávila, José; Ten Brink, Uri S.; Herranz Araújo, Pedro; Von Hilldebrant, Christa; Payero, Juan; Muñoz Martín, Alfonso; Pazos, Antonio; Catalán, Manuel; Granja Bruña, José Luis; Gómez Ballesteros, María
There is renewed interest in studying the active and complex northeastern Caribbean plate boundary to better understand subduction zone processes and for earthquake and tsunami hazard assessments [e.g., ten Brink and Lin, 2004; ten Brink et al., 2004; Grindlay et al, 2005]. To study the active tectonics of this plate boundary, the GEOPRICO-DO (Geological, Puerto Rico-Dominican) marine geophysical cruise, carried out between 28 March and 17 April 2005 (Figure 1), studied the active tectonics of this plate boundary. Initial findings from the cruise have revealed a large underwater landslide, and active faults on the seafloor (Figures 2a and 2c). These findings indicate that the islands within this region face a high risk from tsunami hazards, and that local governments should be alerted in order to develop and coordinate possible mitigation strategies. The cruise collected multibeam bathymetry, gravity, magnetic, high-resolution seismic, deep seismic sounding, and multichannel seismic reflection data, which are currently being processed and interpreted (Table 1). In early November 2005, 10 ocean-bottom seismometers (OBS) that had been deployed northeast of Puerto Rico and the Virgin Islands (Figure 1) during the cruise were recovered. These OBS recorded data during the cruise and the local seismicity between April and October 2005.
Alboran basin, Southern Spain. Part II: Neogene tectonic implications for the orogenic float model
(Marine and Petroleum Geology, 2008) Gómez Ballesteros, María; Rivera, Jesus; Muñoz, Araceli; Muñoz Martín, Alfonso; Acosta, Juan; Carbó Gorosabel, Andrés; Uchupi, E.
We infer that the Alboran Basin, the first western Mediterranean Basin found after crossing Gibraltar, is an orogenic float underlained by a de´ collement system, a multi-layered ductile shear extending from 10km to between 30 and 40km below sea level. This float was formed as consequence of the collision of the African–Eurasian plates in the Oligocene–late Miocene. Synchronous with this compression the float experienced basin wide crustal thinning and subsidence about 25 m/year ago by subcrustal processes. Since latest Miocene the float has undergone compression due to the continuous convergence of Eurasia and Africa. The faults created as a result of this compression are dominated by a conjugate system of northeast trending left-lateral and northwest right-lateral strike–slip faults. This deformation is taking place under a simple shear mechanism. Associated with the northwest and northeast lateral faults are zones of compression trending west and east of north extending from the base of the basin’s north upper slope to the Alboran Ridge. The initial morphology of the Alboran Ridge on the southern side of the Alboran Basin was due to the construction of a volcanic edifice at the northeast end of the ridge and igneous activity along northeast trending fractures southwest of the edifice. At the northeast end of the Alboran Ridge motion along a right-lateral fault cutting across the ridge led to sediment collapse and the creation of a prominent embayment on the ridge’s northwest flank. Deformation is more subdued in the western than in the eastern part of the Alboran Basin, a tectonic style due either to differences in sediment rheology or that the accommodation of the convergence of Africa and Iberia is more diffused and attenuated in the west than in the east.
Relación entre la complejidad estructural frágil y la distribución espacial de la sismicidad en tres regímenes tectónicos diferentes (Sur de Centro América)
(Geotemas, 2000) Muñoz Martín, Alfonso; Arcila, M.; Pérez López, Raúl; Rodríguez Pascua, Miguel Angel; Vicente Muñoz, Gerardo de
Fracturation process is the main geological mechanism for earthquakes generation as well as their magnitude and spatial distribution. In this work we analyze the correlation among a geometric, cinematic and dynamic fault-slip analysis with the magnitude frequency distribution (Ms) and the epicentral setting into three different tectonic areas. In order to compare all these parameters these areas have the same surface (2°x2°) and a similar number of epicentres. The brittle structural complexity has been defined by means an index which depends on the number of active structures as well as the different type of active faults under the present-day stress tensor. The obtained results seem indicate that a bigger index of brittle structural complexity has a good relationship with an increasing of the "b" value and with a bigger complexity in the spatial distribution of earthquakes defined by the fractal dimension (capacity dimension, Dcap).
Análisis de la geometría en profundidad de fracturas conductoras en zonas de baja permeabilidad mediante tomografía eléctrica (El Berrocal, Sistema Central Español)
(Geogaceta, 2007) Muñoz Martín, Alfonso; Olaiz Campos, Antonio José; Vicente Muñoz, Gerardo de; Antón López, Loreto; Elorza, Francisco José; Vicente, Raquel de
The groundwater flow in zones of low permeability, as granites, is mainly associated with zones of fracture. For this reason the characterization of the fractures is fundamental, both in surface as in depth, and must integrate geological information (geological mapping, structural analysis), geophysics (mainly electrical and electromagnetic methods) and geochemistry (radon and others gases) with hydrogeology. In this work we analyze the geophysical response of a strike-slip fault zone by means of three 2D resistivity models. The objective is to investigate the presence of several conductive zones and their geometry in depth. The obtained results allow to control the geometry in depth of the fractures, the gaps between the different mapped traces along the fault zone as well as the thickness of landfill. All this information will be useful for the hidromechanical simulation of the massif, and to check the geometry and gas permeability calculated from emanometry.
Evolución geodinámica del borde oriental de la cuenca del Tajo desde el Oligoceno hasta la actualidad
(2003) Muñoz Martín, Alfonso; Vicente Muñoz, Gerardo de
La integración y aplicación combinada de técnicas y metodologías clásicas e innovadoras de análisis estructural y tectónico en el borde oriental de la cuenca del tajo, ha permitido establecer su evolución geodinámica en tres etapas principales desde el oligoceno hasta la actualidad, cada una de las cuales esta caracterizada por un campo de paleoesfuerzos de tipo compresivo. Esta evolución ha sido establecida mediante una comparación cuantitativa de los datos de acortamiento calculados en las estructuras, el análisis cinemático y dinámico de las mismas, y la elaboración de los modelos numéricos para comprobar la viabilidad de las hipótesis/propuestas finalmente, se ha realizado una integración de todos estos datos en un modelo evolutivo, incluyendo la revisión de los modelos previos y la evolución cinemática del mediterráneo occidental desde el oligoceno hasta la actualidad.
Inversion of moment tensor focal mechanisms for active stresses around the Microcontinent Iberia: Tectonic implications
(Tectonics, 2008) Vicente Muñoz, Gerardo de; Cloetingh, Sierd; Muñoz Martín, Alfonso; Olaiz Campos, Antonio José; Stich, Daniel; Vegas, Ramón; Galindo-Zaldívar, Jesus; Fernández Lozano, Javier
The Iberian microcontinent and its connected oceanic crust are affected by deformations related to the Eurasian-African plate boundary. Active stress inversions from populations of moment tensor focal mechanisms have been performed around and inside the Iberian peninsula, using a total of 213 moment tensor estimates. Main results are: 1) The tensorial solutions show better consistency and lower misfits compared to those obtained previously from first P arrival focal mechanisms. 2) Along the Eurasia- Africa western boundary, the type of active stresses progressively changes easternwards from triaxial extension to uniaxial compression along the Terceira Ridge, the Gloria Fault zone and the Gulf of Cadiz. 3) In the Betics-Alboran-Rif zone, uniaxial extension predominates with Shmax N155ºE trending. 4) In N Algeria, uniaxial compression reappears. 5) The Iberian foreland is currently under strike-slip to uniaxial extension tensorial conditions.
Upper crustal structure of Deception Island area (Bransfield Strait, Antarctica) from gravity and magnetic modelling
(Antarctic Science, 2005) Muñoz Martín, Alfonso; Catalán Morollón, Manuel; Martín Dávila, José; Carbó Gorosabel, Andrés
Deception Island is a young, active volcano located in the south-western part of Bransfield Strait, between the Antarctic Peninsula and the South Shetland archipelago. New gravity and magnetic data, from a marine geophysical cruise (DECVOL-99), were analysed. Forty-eight survey lines were processed and mapped around Deception Island to obtain Bouguer and magnetic anomaly maps. These maps show welldefined groups of gravity and magnetic anomalies, as well as their gradients. To constrain the upper crustal structure, we have performed 2+1/2D forward modelling on three profiles perpendicular to the main anomalies of the area, and taking into account previously published seismic information. From the gravity and magnetic models, two types of crust were identified. These were interpreted as continental crust (located north of Deception Island) and more basic crust (south of Deception Island). The transition between these crustal types is evident in the Bouguer anomaly map as a high gradient area trending NE–SW. Both magnetic and gravity data show a wide minimum at the eastern part of Deception Island, which suggests a very low bulk susceptibility and low density intrusive body. With historical recorded eruptions and thermal and fumarolic fields, we interpret this anomaly as a partially melted intrusive body. Its top has been estimated to be at 1.7 km depth using Euler deconvolution techniques.