Site Effects and Damage Patterns

A set of observations on site effects and damage patterns from the M_w 8.8 Maule, Chile, earthquake is presented, focusing on identification of structural damage variability associated with nonuniform soil conditions and subsurface geology. Observations are reported from: (1) the City of Santiago de Chile (Américo Vespucio Norte Ring Highway, Ciudad Empresarial business park), (2) the Municipality of Viña del Mar, and (3) the City of Concepción, extending over 600 km along the Chilean coast. Reconnaissance information and ground motion recordings from the megathrust event are combined with site investigation data in the regions of interest. Comparisons against macroseismic observations related to uneven damage distribution from the M_w 8.0 1985 Valparaíso earthquake are discussed. Complexities associated with identifying the mechanics and underlying physical processes responsible for the manifestation of these effects are elucidated

Notas sobre el conocimiento limnológico de los gasterópodos paranenses y sus relaciones tróficas. I Ampullariidae

The limnological knowledge about the gasteropods of the Paraná River are rather poor, disperse and very diffícult to find and to be applied to the studies related to their múltiple relationships in the aquatic environment, including their participation in the water trophic cycles. Thus, a first approach to a syntesis of the several advances is intended here, in order to center the main problems and estimúlate possible developmentways as well. Aspects with applied interests are also included (fisheries, sanitary problems, weed control). The treatment of each group will be faced separately because of its extention, begining with the present notes on the Ampullaríidae. The limnological knowledge about the gasteropods of the Paraná River are rather poor, disperse and very diffícult to find and to be applied to the studies related to their múltiple relationships in the aquatic environment, including their participation in the water trophic cycles. Thus, a first approach to a syntesis of the several advances is intended here, in order to center the main problems and estimúlate possible developmentways as well. Aspects with applied interests are also included (fisheries, sanitary problems, weed control). The treatment of each group will be faced separately because of its extention, begining with the present notes on the Ampullaríidae.&nbsp

Anatomy of a high-silica eruption as observed by a local seismic network: the June 2011 Puyehue–Cordón Caulle event (southern Andes, Chile)

High-silica explosive eruptions are one of the most dangerous natural phenomena, yet it is unclear which processes are involved in this infrequent kind of event. We present the first systematic characterization of near-field seismicity associated with a large high-silica eruption analyzing data recorded before, during and after the 4 June 2011 rhyolitic eruption of Puyehue–Cordón Caulle Volcanic Complex (PCCVC). Results of a first-level data processing, developed by the Southern Andean Volcano Observatory (OVDAS) to monitor unrest and the evolution of the eruption, are complemented here with the relocation of hypocenters into a local 1D velocity model, the time series of the b value and the computation of the focal mechanism. This information allows us to define several phases before and after the onset of the eruption, describing details of the space–time evolution of seismicity, defining and characterizing the seismic sources, and identifying the structural control of the magmatic intrusion and stress variations during the eruption. Our results illuminate several underlying processes, with emphasis on the possible role that basement structures had on the storage, transport and evacuation of magma. Integrating our results with previous findings based on satellite geodesy and petrology of erupted materials, we discuss general conceptual models regarding destabilization of structurally controlled acidic magmatic systems, the pass from unrest to eruption, and changes in eruptive style and waning phases of eruptions, with broader implications for monitoring and forecast of violent silicic eruptions.</p

Contribución al conocimiento limnológico de moluscos pelecipodos en la Cuenca del Plata, con particular referencia a sus relaciones tróficas

Despite the undeniable limnological importance o f the malacological fauna in the waters o f Rio de la Plata Basin, the current knowledge on this topic is very poor, fragmentary and geographically limited. Moreover existing limnological literature generally focuses on their very complex taxonomic problems. Thus, this paper conceived on the basis o f available literature, unpublished data and our own research, represents a first attemt to bring together the most significant limnological Information related to the mollusks o f the above mencioned basin and to begin with, the pelecipod s. Also it intends to provide as far as posible a complete and integrative panorame of the role o f different species in its participation in trophic nets, specially those dealing with the fish and físheries. The effect and possible future consequences of the invasión on this waters by species o f the genus Corbicula, are also considered.Despite the undeniable limnological importance o f the malacological fauna in the waters o f Rio de la Plata Basin, the current knowledge on this topic is very poor, fragmentary and geographically limited. Moreover existing limnological literature generally focuses on their very complex taxonomic problems. Thus, this paper conceived on the basis o f available literature, unpublished data and our own research, represents a first attemt to bring together the most significant limnological Information related to the mollusks o f the above mencioned basin and to begin with, the pelecipod s. Also it intends to provide as far as posible a complete and integrative panorame of the role o f different species in its participation in trophic nets, specially those dealing with the fish and físheries. The effect and possible future consequences of the invasión on this waters by species o f the genus Corbicula, are also considered

The 2010<i>M</i>_w8.8 Maule, Chile earthquake: Nucleation and rupture propagation controlled by a subducted topographic high

Knowledge of seismic properties in an earthquake rupture zone is essential for understanding the factors controlling rupture dynamics. We use data from aftershocks following the Maule earthquake to derive a three-dimensional seismic velocity model of the central Chile forearc. At 36°S, we find a highvp (&gt;7.0 km/s) and high vp/vs(?1.89) anomaly lying along the megathrust at 25 km depth, which coincides with a strong forearc Bouguer gravity signal. We interpret this as a subducted topographic high, possibly a former seamount on the Nazca slab. The Maule earthquake nucleated at the anomaly's updip boundary; yet high co-seismic slip occurred where the megathrust is overlain by lower seismic velocities. Sparse aftershock seismicity occurs within this structure, suggesting that it disrupts normal interface seismogenesis. These findings imply that subducted structures can be conducive to the nucleation of large megathrust earthquakes, even if they subsequently hinder co-seismic slip and aftershock activity

Notas sobre el conocimiento limnológico de los gasterópodos paranenses y sus relaciones tróficas. II Planorbidae, con aspectos distribucionales y sanitarios

The present remarks on the family Planorbidae constitute a further work o f a series of contributions tending to fumish an integrated overview of the Paraná river’s malacologic fauna, the knowledge of which is most limited, particularly conceming thetaxonomic, biological and limnological aspects. To this effect, the aim of this work is, as well, to give an idea of its energy transfer to fishes and of its importance. This is best observed in the planorbids of the genus Biomphalaria, not particularly because of the importance of such energy contribution, but due to the preying capacity, consumption pressure, and consequent population control performed by certain fishes on these gastropods, some of which species are vectors of schistosomiasis. The fact becomes especially relevant when a sustained advance of this parasitosis towards Argentinianwaters is being noticed; for this reason, thorough investigations of this problem are suggested so as to prevent (or at least reduce) this serious threat which has to be realistically assumed..The present remarks on the family Planorbidae constitute a further work o f a series of contributions tending to fumish an integrated overview of the Paraná river’s malacologic fauna, the knowledge of which is most limited, particularly conceming thetaxonomic, biological and limnological aspects. To this effect, the aim of this work is, as well, to give an idea of its energy transfer to fishes and of its importance. This is best observed in the planorbids of the genus Biomphalaria, not particularly because of the importance of such energy contribution, but due to the preying capacity, consumption pressure, and consequent population control performed by certain fishes on these gastropods, some of which species are vectors of schistosomiasis. The fact becomes especially relevant when a sustained advance of this parasitosis towards Argentinianwaters is being noticed; for this reason, thorough investigations of this problem are suggested so as to prevent (or at least reduce) this serious threat which has to be realistically assumed

The Influence of Masculinity on Male Latino Adolescents’ Perceptions Regarding Dating Relationships and Dating Violence

In the United States, teen dating violence (TDV) is a concern across ethnic groups. Attitudes and correlates of violence differ by gender, culture, and acculturation. This study used a qualitative interpretive approach. Data were obtained in focus groups with 23 Latino male adolescents. Themes reflected contexts of participants’ lives, and definitions and nature of dating relationships and TDV. Participants described the importance of respecting dating partners, the destructive effects of TDV, and the pressure to display masculinity that can lead some young men to perpetrate TDV. These results may advance culturally relevant interventions to promote healthy relationships and prevent dating violence

Rapid South Atlantic spreading changes and coeval vertical motion in surrounding continents: Evidence for temporal changes of pressure-driven upper mantle flow

International audienceThe South Atlantic region displays (1) a topographic gradient across the basin, with Africa elevated relative to South America, (2) a bimodal spreading history with fast spreading rates in Late Cretaceous and Eo-Oligocene, and (3) episodic regional uplift events in the adjacent continents concentrated in Late Cretaceous and Oligocene. Here we show that these observations can be linked by dynamic processes within Earth's mantle, through temporal changes in asthenosphere flow beneath the region. The topographic gradient implies westward, pressure-driven mantle flow beneath the basin, while the rapid spreading rate changes, on order 10 million years, require significant decoupling of regional plate motion from the large-scale mantle buoyancy distribution through a mechanically weak asthenosphere. Andean topographic growth in late Miocene can explain the most recent South Atlantic spreading velocity reduction, arising from increased plate boundary forcing associated with the newly elevated topography. But this mechanism is unlikely to explain the Late Cretaceous/Tertiary spreading variations, as changes in Andean paleoelevation at the time are small. We propose an unsteady pressure-driven flow component in the asthenosphere beneath the South Atlantic region to explain the Late Cretaceous/Tertiary spreading rate variations. Temporal changes in mantle flow due to temporal changes in regional mantle pressure gradients imply a correlation of horizontal and vertical motions: we find that this prediction from our models agrees with geologic and geophysical observations of the South Atlantic region, including episodes of passive margin uplift, regional basin reactivation, and magmatic activity