132 research outputs found

    Paleoseismic results from multiple trenching analysis along a silent fault: The El Camp fault (Tarragona, northeastern Iberian Peninsula)

    Get PDF
    We present the paleoseismological analysis of the El Camp fault scarp. Paleoseismology constitutes the key methodology for any real estimate of seismic hazard in low-slip-rate areas with no reported historical earthquakes. The recent tectonic activity of this fault is evidenced by a young mountain front and a fault scarp which cuts Quatern a ry alluvial fans. A regional geological analysis indicates that three generations of alluvial fans are cut by the fault. Absolute (TL and U/Th) and relative datings show that the oldest fan is 300 ka old and the intermediate one is 125 ka old. The study of 7 trenches and the absolute datings performed (TL, U/Th, radiocarbon as well as pollen analysis) revealed the following: 1) the El Camp fault consists of two segments (the nort h e rn end of the southern segment is located close to Po rquerola creek); 2) only the southern segment has been active since 125 ka; 3) the fault is seismogenic because it is associated with liquefaction features and colluvial wedges; 4) the El Camp fault has produced at least three well constrained surface-rupturing earthquakes since 125 ka (events Z, Y, and X). Based on the different tectonic features observed in the trenches, the recurrence period of large earthquakes during this period was estimated to be around 30 ka and the elapsed time to be around 3000 yr. Using the fault length and the ve rtical displacement per event, the largest estimated earthquake had a magnitude of Mw 6.7.Se presenta el análisis paleosismológico de la falla de El Camp. La paleosismología es una herramienta imprescindible para la caracterización sísmica de fallas activas, lentas y sin sismicidad histórica y, por lo tanto, para cálculos de peligrosidad sísmica. La falla de El Camp muestra evidencias de actividad tectónica: un frente montañoso joven y un escarpe de falla que afecta a abanicos aluviales cuaternarios. Un análisis geológico regional, previo al paleosismológico, muestra tres generaciones de abanicos aluviales afectados por la falla. El techo de éstos ha sido datado (U/Th y TL en caliches) en 300 y 125 ka para las dos generaciones más antiguas. Del estudio de 7 trincheras y de las dataciones por U/Th, TL, radiocarbono y polen se han obtenido los siguientes resultados: 1) La falla tiene dos segmentos con límite en el barranco de la Po rquerola. Solamente el segmento al sur de este punto ha sido activo posteriormente a 125 ka. 2) La falla de El Camp es sismogénica. 3) Se han caracterizado un mínimo de tres eventos posteriores a 125 ka (eventos Z, Y, y X). 4) El período intersísmico reciente se ha estimado en 30 ka. 5) El tiempo transcurrido desde el último terremoto es de 3000 años. 6) La magnitud del terremoto máximo es MW 6. 7

    The effect of onboard passengers’ seating arrangement on the vertical ride comfort of a high-speed railway vehicle

    Get PDF
    This research is concerned with the impact of onboard passengers’ seating arrangement on the carbody flexural vibrations of a high-speed railway vehicle. In this regard, the previously developed passenger body-seat models are used to consider the dynamic influence of the passengers. The carbody is modeled using the Euler–Bernoulli beam model to evaluate its flexural deformation. The frequency-domain analysis demonstrates that the carbody behaves almost like a rigid body when the vehicle is full of passengers. It is established that the passengers' presence causes a 31% enhancement of the ride quality determined based on EN 12299 standard for a fully occupied vehicle compared with an empty car. A scaled model of a ratio of 1:24.5 of the Shinkansen vehicle is constructed for validation purposes. The experimental results exhibit a similar trend as found by the simulations in terms of the impact of the passengers’ distribution on the carbody flexural vibrationsPostprint (author's final draft

    Damage on a Main Gas Pipeline Due to Landslide of Soils Derived From Volcanic Ashes in Colombia

    Get PDF
    In December 2011 a great proportion slope failed affecting the main gas pipeline (20” diameter) that supplies Colombia’s southwest area. The landslide involved materials formed by soils derived from volcanic ashes and residual soils, typical in Colombia’s central zone, which acquired great energy flowing in an avalanche through the natural watercourse. The avalanche generated soil erosion over the torrent banks, generating the watercourse deepening and the deterioration of adjacent slopes over which the pipeline runs. There were identified as landslides triggering aspects the atypical raining period due to “La Niña” climatic phenomenon and the soils removal at the slope base due to a minor stream. The article contains an analysis based on the characterization of this particular soil and the main landslide and avalanche incidence on the adjacent slopes stability. Additionally, it presents the results of the numerical soil-pipe interaction analysis with finite elements models that was completed to define and design the stabilization works

    Distribution, Abundance and Molecular Analysis of Genus Barbadocladius Cranston & Krosch (Diptera, Chironomidae) in Tropical, High Altitude Andean Streams and Rivers

    Get PDF
    The distribution of the genus Barbadocladius Cranston & Krosch (Diptera: Chironomidae), previously reported from Chile to Bolivia, has extended northwards. Larvae, pupae and pupal exuviae of this genus have been found in the high mountain tropical streams of Peru to 9°22′56″, but are restricted to very high altitude streams (altitudes over 3,278 m asl) compared to the lower altitude streams (below 1,100 m asl) in which the genus is reported in Chile and Argentina. Based on morphological studies, both described species in the genus, Barbadocladius andinus Cranston & Krosch and Barbadocladius limay Cranston & Krosch, have been found in Peru as pupae or pupal exuviae. Morphological analysis of the larvae and pupae revealed no differences between the two described species from Patagonia and Peru, which are of similar size and with a similar armament of hooklets and spines in pupal tergites and sternites. However, molecular analysis of larvae and pupae revealed that in Peru, there are at least two different evolutionary lines, one distributed widely and another restricted to one site. Phylogenetic analysis (using cox1 mitochondrial sequences) of all available sequences of Barbadocladius shows that the Chilean and Argentinean material differs from that of Peru. Therefore, a total of four molecular segregates are identified, although morphologically, neither larvae nor the pupae may be differentiated

    Revista de Vertebrados de la Estación Biológica de Doñana

    Get PDF
    The Osteology of Barbus bocagei (Steindachner, 1866) (Pisces: Cyprinidae).El crecimiento del Cacho (Leuciscus cephalus pyraenaicus Günther, 1862) en el rio Jarama (cuenca del Tajo)Contribución al estudio de la bermejuela, Rutilus arcasi, Steindachner 1866 de la cuenca del Júcar (Osteichthyes: Cyprinidae) 1. MorfometríaDimensiones, estructura, forma y disposición en la cavidad de los nidos de Corvus monedula.Variaciones altitudinales en la composición de las comunidades nidificantes de aves de Sierra Nevada (Sur de España)Ecomorfología de una comunidadde Passeriformes en la Sierra de Cazorla, SE de EspañaLa Distribución del pez-sol (Lepolllis gibbostlS L.) en la Península IbéricaSobre la distribución de Barbus haasi (OSTARIOPHYSI: CYPRINIDAE)La Distribución de Barbus bocagei STEINDACHNER, 1865 (OSTARIOPHYSI: CYPRINIDAE) en la Península IbéricaLighy effects on circadian locomotor activity of Lacerta lepida under constant temperatureEvaluación de diferentes métodos para estimar el área de campeo de dos especies de iguánidos.Un Casal de Cartaxo-Nottenho (Saxicola rubetra) a criar em Portugal.Nidificación de Passer hispaniolensis en antiguos nidos de Dendrocopos major thanneri.Observación de un lince ibérico (Lynx pardina) en la provincia de Lugo. Norte de España.El Visón americano, Mustela vison SCHREBER, 1777 (MAMMALIA, MUSTELIDAE) en Cataluña, N.E. de la Península Ibérica.Peer reviewe

    The Cricotopus (Oliveiriella) (Diptera: Chironomidae) of the High Altitude Andean Streams, with Description of a New Species, C. (O.) rieradevallae

    Get PDF
    The genus Oliveiriella (Chironomidae, Orthocladiinae) was erected by Wiedenbrug & Fittkau (1997). The adults have characteristic black spots on their wings and other characteristics similar to the genus Cricotopus. Pupal skins are very characteristic with strong short spines in the anal lobe instead of setae, while larvae are distinguishable by the long anal papillae and the intense blue color of their body. However, Andersen et al (2013) consider Oliveiriella as a subgenera of Cricotopus. In this paper, using the sequences of the cox1 gene, we conclude that Oliveiriella should be considered a subgenus within Cricotopus, confirming its status in Andersen et al (2013). Furthermore, we describe Cricotopus (Oliveiriella) rieradevallae Prat & Paggi sp. n. from the Saltana river (Ecuador). The adult males, females, and preimaginal stages of the two species of subgenus Oliveiriella known from South America Cricotopus (O.) almeidai n. comb. from Peru, Brazil, and Argentina and Cricotopus (O.) sanjavieri n. comb. from Argentina are compared with those of Cricotopus (O.) rieradevallae sp. n. from Ecuador. The differences allow the distinction of the three species. The cox1 gene reveals that at least three different undescribed species of the same subgenus are present in the high-altitude tropical Andes. The morphology of the available pupae and pupal exuviae reveals the presence of several morphotypes that are candidates to be described as new species. A key used to distinguish these pupal morphotypes is provided, including the three described species. Additionally, the distribution of the subgenus is discussed

    Temporal variation in black-caiman-nest predation in varzea of central Brazilian amazonia

    Get PDF
    On the Amazon floodplain, the main predators of black caiman (Melanosuchus niger) eggs are jaguars (Panthera onca), tegu lizards (Tupinambis teguixim), capuchin monkeys (Sapajus macrocephalus) and humans (Homo sapiens). In this study, we investigated the relationship between predator attacks on nests and incubation period, and evaluated the influence of initial predation on subsequent predation in the Mamirauá Sustainable Development Reserve. We also evaluated the influence of presence of females near the nests and manipulation of nests on the occurrence of attacks. We compared results from data obtained with camera traps and vestiges left by predators on estimates of rates of predation by different predators. Egg predation was recorded in 32% of the 658 black caiman nests monitored during two years. Our results suggest that the probability of predation on black caiman eggs is relatively constant throughout the incubation period and that predation on eggs was lower when adults, presumably females, were present. Careful opening of nests and handling of eggs did not increase the number of attacks on black caiman nests. Nest opening by a predator appeared to increase the chances of a subsequent attack because most of the attacks on nests occurred soon after a predator first opened the nest. However, attacks by another species of predator do not appear to be necessary to initiate attacks by any other species of predator. Results based on camera traps and vestiges differed, but use of vestiges was adequate for identifying the principal predators on eggs in black caiman nests and, in many circumstances, the vestiges may be better for estimating predation by humans. In this study, opening nests and handling eggs did not increase the number of attacks on black caiman nests. © 2017 Torralvo et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited
    corecore