Damages observed in locations of Oaxaca due to the Tehuantepec Mw8.2 earthquake,Mexico     

Pozos-Estrada  Adrián  Chávez  Marcos M.  Jaimes  Miguel Á.  Arnau  Oriol  Guerrero  Héctor 《Natural Hazards》2019,97(2):623-641

On September 7, 2017, at 23:49 h (local time), a Mw8.2 intermediate-depth normal-fault earthquake occurred in the Gulf of Tehuantepec, 133 km away from Pijijiapan, Chiapas, and about 700 km away from Mexico City. This event caused 95 fatalities and severe damage to different types of structures located close to the epicenter. The main objective of this work is to present observed damages caused in the state of Oaxaca by this earthquake, which were mainly concentrated in self-built houses and historical and ancient buildings. The locations visited by the reconnaissance team of the Institute of Engineering from UNAM in Oaxaca included Salina Cruz, Tehuantepec, Ixtaltepec, Juchitán, Huatulco and La Ventosa.

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A depth average SPH model including μ(I) rheology and crushing for rock avalanches     

Alberto Longo  Manuel Pastor  Lorenzo Sanavia  Diego Manzanal  Miguel Martin Stickle  Chuan Lin  Angel Yague  Saeid Moussavi Tayyebi 《国际地质力学数值与分析法杂志》2019,43(5):833-857

Classical depth-integrated smoothed particle hydrodynamics (SPH) models for avalanches are extended in the present work to include a μ(I)− rheological model enriched with a fragmentation law. With this improvement, the basal friction becomes grain distribution dependent. Rock avalanches, where grain distribution tends to change with time while propagating, are the appropriate type of landslide to apply the new numerical proposal. The μ(I)− rheological models considered in the present work are those of Hatano and Gray, combined with two different fragmentation laws, a hyperbolic and a fractal-based law. As an application, Frank avalanche, which took place in Canada in 1903, is analyzed under the scope of the present approach, focusing in the influence of the rheological and fragmentation laws in the evolution of the avalanche.  相似文献   

GPS differential code biases determination: methodology and analysis   总被引：1，自引：1，他引：0  

Jaume Sanz  J. Miguel Juan  Adrià Rovira-Garcia  Guillermo González-Casado 《GPS Solutions》2017,21(4):1549-1561

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Volcanes y erupciones volcánicas de España estudiados y descritos en estos ultimos años     

Maximino San Miguel De La Camara 《Bulletin of Volcanology》1950,10(1):89-116

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Estimation of Surface-Layer Scaling Parameters in the Unstable Boundary Layer: Implications for Orographic Flow Speed-Up     

José Luís Argaín  Miguel A. C. Teixeira  Pedro M. A. Miranda 《Boundary-Layer Meteorology》2017,165(1):145-160

A method is proposed for estimating the surface-layer depth \((z_s)\) and the friction velocity \((u_*)\) as a function of stability (here quantified by the Obukhov length, L) over the complete range of unstable flow regimes. This method extends that developed previously for stable conditions by Argaín et al. (Boundary-Layer Meteorol 130:15–28, 2009), but uses a qualitatively different approach. The method is specifically used to calculate the fractional speed-up \((\varDelta S)\) in flow over a ridge, although it is suitable for more general boundary-layer applications. The behaviour of \(z_s \left( L\right) \) and \(u_*\left( L\right) \) as a function of L is indirectly assessed via calculation of \(\varDelta S\left( L\right) \) using the linear model of Hunt et al. (Q J R Meteorol Soc 29:16–26, 1988) and its comparison with the field measurements reported in Coppin et al. (Boundary-Layer Meteorol 69:173–199, 1994) and with numerical simulations carried out using a non-linear numerical model, FLEX. The behaviour of \(\varDelta S\) estimated from the linear model is clearly improved when \(u_*\) is calculated using the method proposed here, confirming the importance of accounting for the dependences of \(z_s\left( L \right) \) and \(u_*\left( L \right) \) on L to better represent processes in the unstable boundary layer.  相似文献   

Joint Management of Surface and Ground Water Supplies   总被引：10，自引：0，他引：10  

Hakan Ba&#;a&#;ao&#;lu  Miguel A. Mari&#;o 《Ground water》1999,37(2):214-222

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Tectonic significance of an earthquake sequence in the Zacoalco half-graben, Jalisco, Mexico     

Javier F. Pacheco  Carlos A. Mortera-Gutirrez  Hugo Delgado  Shri K. Singh  Raúl W. Valenzuela  Nicolai M. Shapiro  Miguel A. Santoyo  Alejandro Hurtado  Ricardo Barrn  Esteban Gutirrez-Moguel 《Journal of South American Earth Sciences》1999,12(6):55

We studied a sequence of small earthquakes that occurred during the months of April and May of 1997, in Jalisco, southwestern Mexico. The earthquakes were located along a set of active faults that form the Zacoalco half-graben (La Lima fault system), west of Lake Chapala, within the rift–rift–rift triple junction. A total of 33 events were located, with magnitudes ranging from 1.5 to 3.5, recorded by a portable array of broadband seismographs. We identified two groups of events: one corresponding to a shallow normal fault, synthetic to La Lima fault system, and another group associated with a deeper fault. The events that occurred on the synthetic fault show normal faulting oriented on a NW–SE plane, dipping shallowly towards the SW. The other group of mechanisms showed either a normal fault oriented NW–SE and dipping steeply to the NE, or a very shallow-dipping normal fault, dipping to the SW. Earthquake distribution and fault plane solutions suggest that the Zacoalco half-graben developed from blocks that rotate as slip occurs on listric faults. These mechanisms could represent the type of motion expected for larger earthquakes in the area, like the one that occurred in 1568.  相似文献   

Tectonic implications of the earthquake swarm of 1997 in the Michoacan Triangle, Mexico     

Javier F. Pacheco  Carlos Valds-Gonzlez  Hugo Delgado  Shri K. Singh  F. Ramn Zuiga  Carlos A. Mortera-Gutirrez  Miguel A. Santoyo  Jaime Domínguez  Ricardo Barrn 《Journal of South American Earth Sciences》1999,12(6):73

An earthquake swarm occurred during February and March 1997 in the vicinity of the Tancitaro Volcano, in the southern part of the tectonically complex Michoacan Triangle. A study of these events provides an opportunity to map the active faults in the area and to learn if the orientation and the sense of motion on these faults are consistent with the mapped faults and the alignment of cinder cones in the region. The foci of 230 earthquakes, which could be located, are distributed between 10 and 18 km depth, and show an alignment in, roughly, a NE direction. The focal mechanisms and seismic moments of the 27 best-recorded events were determined by waveform modeling of P and S waves. These mechanisms show two distinct patterns. More than 50% of the solutions are left-lateral strike–slip mechanisms with a normal component. The preferred fault plane strikes NE. Another group of events, probably caused by triggered seismicity on the Chapala–Oaxaca fault zone, shows left-lateral strike–slip mechanisms with a large-thrust component on NW-trending faults. S wave splitting shows 1–2.5% crustal-anisotropy. The direction of the anisotropy coincides with the NE alignment of events, and the preferred nodal plane. This is also the alignment of cinder cones, suggesting that preexisting fractures and cracks are responsible for the seismicity and anisotropic behavior of the crust. The resulting stress orientation, NE compression, is the one expected for the fore-arc region. We conclude that although Michoacan Triangle lies in the Trans-Mexican Volcanic Belt, it does not form part of this stress province where the stress orientation is NS extension.  相似文献   

Palaeokarst and rauhwacke development,mountain uplift and subaerial sliding of tectonic sheets (northern Sierra de los Filabres,Betic Cordilleras,Spain)     

Orozco  Miguel  Molina  José Miguel  Crespo-Blanc  Ana  Alonso-Chaves  Francisco Manuel 《Geologie en Mijnbouw》1999,78(1):103-117

The rauhwackes near Serón in the northern Sierra de los Filabres (S Spain), previously considered as true tectonic breccias, are reinterpreted on the basis of sedimentological, geomorphological and geometrical evidence as subaerial or nearly subaerial sedimentary deposits. Channel fills, parallel lamination, cross-lamination, graded bedding, sedimentary clastic dykes and other sedimentary structures and features occur in the rauhwacke body. These sedimentary rocks correspond to continental deposits of alluvial and karstic origin deposited over a karstified erosional surface of Nevado–Filabride marbles. Although no fossils have been found in the rauhwackes, a Tortonian age for these rocks is suggested on the basis of structural arguments and lithostratigraphic data from the nearby Almanzora basin. The rauhwackes were buried by slabs of Alpujarride rocks that gravitationally slid over them during the uplifting of the Sierra de los Filabres.  相似文献   

Taxonomic revision of Cylindroporella ? lusitanica Ramalho, 1970: In search for the origins of the Family Dasycladaceae          下载免费PDF全文

Bruno R. C. Granier  Ana C. Azerêdo  Miguel M. Ramalho 《Island Arc》2017,26(3)

A study of new material of Cylindroporella ? lusitanica Ramalho, 1970, from the Upper Jurassic (Oxfordian) strata of Portugal identified features not observed previously. This includes the pattern of its laterals, including the gametophores. The algal body plan is unique and justifies the taxonomic reassessment of this species and the introduction of Barattoloporellopsis n. gen. Furthermore this species is most likely a primitive Dasycladaceae, a “missing link” between the modern ones (starting from the Cretaceous times) and their Jurassic ancestors.  相似文献