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
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Item 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 deFracturation 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).Item Características de los tensores de esfuerzos activos entre la Dorsal Centroatlántica y la Península Ibérica.(Geotemas, 2000) Vicente Muñoz, Gerardo de; Martín Velázquez, Silvia; Rodríguez Pascua, Miguel Angel; Muñoz Martín, Alfonso; Arcila, M.; Andeweg, BerndThe orientation of the principal stresses and the principal stress difference ratio has been determined along the southwestern boundary of the Euroasiatic plate with Northamerican and African plates by inversion method of focal mechanisms of earthquakes. The ridge push (30~ to 65Q N) ranges from E-W to ESE-WSW, with R values that show a triaxial extensional stress. The state of stress changes to strike-slip regime in the transform fault zones, and the Shmax strike turns clockwise to NW in the dextral strike-slip faults and counterclockwise to the NE in the sinistral ones. Along the margin between the Euroasiatic-African plates, from the Azores triple junction to Algeria, Shmax keeps a constant NW-SE strike but the stress ratio values range from triaxial extensional stress state, to the West, to uniaxial compresive stress state, to the East, passing through a strike-slip regime in the middle zone. In this context and with a widely NWSE Shmax, strike-slip and extensional stresses prevail in most Iberian peninsula, whereas southwards it is dominated by uniaxial compresive stresses.Item Marco geotectónico para el noroeste de Sur América y Sur de Centro América(Geotemas, 2000) Arcila, M.; Muñoz Martín, Alfonso; Vicente Muñoz, Gerardo deDue to the convergence of four major plates (Nazca, South America, Cocos and Caribbean) with a group of minor blocks between Central and South America region, it is a tectonic complex area. These small plates have different relative movements respect to the main Plates. Since 1969 a group of tectonic models including different plate borders and kinematic relationships have been proposed. Nowadays there are several databases with homogeneous quality including seismicity, topography, CPS and magnetic anomalies. These databases allow building a new geotectonic model by means of the integration of all o f them. We have analyzed the topography, seismicity, actual stress regimes and plate kinematics in order to propose a new geotectonic model at the south of Central America and the northwester of South America.Item Características de los tensores de esfuerzos activos entre la Dorsal Centroatlántica y la Península Ibérica(Geotemas, 2000) Vicente Muñoz, Gerardo de; Martín Velázquez, Silvia; Rodríguez Pascua, Miguel Angel; Muñoz Martín, Alfonso; Arcila, M.; Andeweg, BerndThe orientation of the principal stresses and the principal stress difference ratio has been determined along the southwestern boundary of the Euroasiatic plate with Northamerican and African plates by inversion method of focal mechanisms of earthquakes. The ridge push (30~ to 65Q N) ranges from E-W to ESE-WSW, with R values that show a triaxial extensional stress. The state of stress changes to strike-slip regime in the transform fault zones, and the Shmax strike turns clockwise to NW in the dextral strike-slip faults and counterclockwise to the NE in the sinistral ones. Along the margin between the Euroasiatic-African plates, from the Azores triple junction to Algeria, Shmax keeps a constant NW-SE strike but the stress ratio values range from triaxial extensional stress state, to the West, to uniaxial compresive stress state, to the East, passing through a strike-slip regime in the middle zone. In this context and with a widely NWSE Shmax, strike-slip and extensional stresses prevail in most Iberian peninsula, whereas southwards it is dominated by uniaxial compresive stresses.