Person: Muñoz Martín, Alfonso
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First Name
Alfonso
Last Name
Muñoz Martín
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Geológicas
Department
Geodinámica, Estratigrafía y Paleontología
Area
Geodinámica Interna
Identifiers
6 results
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Now showing 1 - 6 of 6
Item 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, AliciaLa 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.Item 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, MaríaThere 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.Item Una década de investigación sobre el geopotencial(Investigación y ciencia, 2011) Catalán, Manuel; Muñoz Martín, AlfonsoItem Gravity modeling of the Muertos Trough and tectonic implications (north-eastern Caribbean)(Marine Geophysical researches, 2010) Granja Bruña, José Luis; Muñoz Martín, Alfonso; Ten Brink, Uri S.; Carbó Gorosabel, Andrés; Llanes Estrada, Pilar; Martín Dávila, José; Córdoba Barba, Diego; Catalán, ManuelThe Muertos Trough in the northeast Caribbean has been interpreted as a subduction zone from seismicity, leading to infer a possible reversal subduction polarity. However, the distribution of the seismicity is very diffuse and makes definition of the plate geometry difficult. In addition, the compressive deformational features observed in the upper crust and sandbox kinematic modeling do not necessarily suggest a subduction process. We tested the hypothesized subduction of the Caribbean plate’s interior beneath the eastern Greater Antilles island arc using gravity modeling. Gravity models simulating a subduction process yield a regional mass deficit beneath the island arc independently of the geometry and depth of the subducted slab used in the models. This mass deficit results from sinking of the less dense Caribbean slab beneath the lithospheric mantle replacing denser mantle materials and suggests that there is not a subducted Caribbean plateau beneath the island arc. The geologically more realistic gravity model which would explain the N–S shortening observed in the upper crust requires an overthrusted Caribbean slab extending at least 60 km northward from the deformation front, a progressive increase in the thrusting angle from 8 to 30 reaching a maximum depth of 22 km beneath the insular slope. This new tectonic model for the Muertos Margin, defined as a retroarc thrusting, will help to assess the seismic and tsunami hazard in the region. The use of gravity modeling has provided targets for future wide-angle seismic surveys in the Muertos Margin.Item Margen Continental Gallego; Zona Económica Exclusiva Española (ZEEE): mapas temáticos de anomalías gravimétricas de aire libre y Bouguer (2012)(2012) Martín Dávila, José; Catalán, Manuel; Larran, M.; Somoza, Luis; León, R.; Gonzalez, F.J.; Carbó Gorosabel, Andrés; Muñoz Martín, Alfonso; Granja, J.L.; Llanes Estrada, P.; Gómez Ballesteros, María; Druet, M.; Acosta, JuanItem Geomagnetic secular variation of Bransfield Strait (Western Antarctica) from analysis of marine crossover data(Geophysical journal international, 2005) Catalán, Manuel; Agudo, Luis Miguel; Muñoz Martín, AlfonsoTracking the secular variation of the geomagnetic field in the past is severely limited in some cases by factors relating to the remoteness of the sites. This is maximal in the Antarctic where the remote location and severe climate lead to logistic limitations that make it difficult to keep a continuous record of magnetic field variations. From the magnetic information available from historical marine expeditions, it is possible to infer this time-varying component from the comparison of readings at crossovers. This study focuses on this technique, discusses the impact of the different error sources and proposes a simple mathematical procedure to infer average secular variation rates. The result is validated by comparing it with local data from the Arctowski and Livingston magnetic observatories, sited in the area. Additionally, using a high-quality data set from a local area in the neighbourhood of Deception Island, we have detected a systematic distribution in its secular variation. This dichotomy has been interpreted in terms of a volcano-magnetic signal. This fact and the nature of its principal mechanisms are analysed and discussed.