Seismic risk analysis of urban non-engineered buildings: application to an informal settlement in Mérida,Venezuela

Seismic risk scenarios are obtained for an informal settlement in Mérida (Venezuela), which is representative of an important number of urban areas in earthquake-prone regions of the developing world. The vulnerability indices of the buildings range between 0.64 and 0.80 on a scale of 0 to 1. In an intensity IX earthquake scenario, more than 32% of the buildings would suffer damage of grade 4 (extensive) or greater. A structural analysis of the buildings in the study area shows that they are unsafe for gravity loads, and that the seismic demands exceed the strength of the constructions. Simple and comparatively inexpensive measures can improve the seismic performance of these buildings; the vulnerability can be reduced by about 51%. In an intensity IX earthquake scenario, the expected economic loss before retrofitting the buildings is US5.36 million, with 275 fatalities; once retrofit has been carried out, the resulting figures are US5.36 million, with 275 fatalities; once retrofit has been carried out, the resulting figures are US0.39 million and 10 fatalities. Retrofit would cost US1.04 million, whereas reconstruction would cost US1.04 million, whereas reconstruction would cost US19 million.     

Triangulation-to-GPS and GPS-to-GPS geodesy in Trinidad, West Indies: Neotectonics, seismic risk, and geologic implications

We estimated horizontal velocities at 25 sites first surveyed in a 1901-1903 British Ordnance Survey triangulation and then resurveyed with GPS in 1994-1995 to identify Trinidad's principal active on-land faults, quantify fault-slip-rates, and test for elastic locking. Our best-fit single-fault elastic dislocation model put 12 ± 3 mm/yr of dextral strike-slip on the Central Range Fault (1-2 km locking depth), an apparently aseismic active fault. The estimated motions also showed statistically insignificant horizontal motion (2.2 ± 1.8 mm/yr of right-slip; 2.7 ± 2.0 mm/yr of N-S shortening) on the eastward on-strike extension of the El Pilar Fault, known to be the active transform fault in Venezuela. Repeat GPS measurements made between 1994 and 2005 at two sites spanning the island north to south showed a 14 ± 3 mm/yr eastward (plate-motion-parallel) dextral velocity differential, consistent with our best-fit historic (1901-1995) fault-slip-rate. Paleoseismology trenching demonstrates that the Central Range Fault cuts <5000-year-old sediment and is capped by ∼550-year-old sediment, suggesting that it may be locked and may have ruptured at least once during this time interval. About ∼5 mm/yr of slip could be taken up on the Los Bajos Fault and additional faults in the offshore south of Trinidad. The existing 1901-1995 and 1994-2005 geodetic data alone cannot resolve whether the Central Range Fault is essentially creeping (≤1-2 km locking depth) or locked to a more standard depth of 10 km.     

Do Spartina maritima Plantations Enhance the Macroinvertebrate Community in European Salt Marshes?

Ecological restoration of salt marshes using plantations may enhance the macroinvertebrate community, but little is known about the development of benthic macroinvertebrates after ecological engineering projects in European salt marshes. This study analyzed the environment and the macroinvertebrate community in European salt marshes 3 years after restoration using Spartina maritima plantations in comparison with non-restored and preserved marshes in Odiel Marshes (Southwest Iberian Peninsula). We hypothesized that planting Spartina maritima on intertidal mudflats would increase species richness and diversity (Shannon–Weaver index) of the benthic macroinvertebrate community by increasing environmental heterogeneity, providing feeding resources and improving sediments characteristics. Benthic macrofauna samples (composed mainly of annelids, crustaceans, and mollusks) were sampled in plots of 20 cm?×?25 cm to 5 cm depth between +1.8 and +3.0 m above Spanish Hydrographic Zero. Sediment organic matter content, bulk density, pH, and redox potential were the variables that best explained macroinvertebrate distribution. Restored marshes achieved similar diversity and even higher specific richness than preserved marshes, although with differences in species composition. Non-restored marshes showed the lowest diversity. Restored and preserved marshes did not differ in total abundance or biomass of macroinvertebrates, both being higher than in non-restored marshes. The macroinvertebrate communities in preserved and non-restored marshes showed the largest difference in taxa composition, with restored marshes occupying an intermediate position. Salt marsh restoration using S. maritima increased the complexity (ecological diversity and species richness) and abundance of the benthic macroinvertebrate community. Our study offers new information about the role of salt marsh plants in mediating faunal communities via ecological engineering projects.     

A Search for Pulsating, Mass-Accreting Components in Algol-Type Eclipsing Binaries

We present a status report on the search for pulsations in primary componants of Algols systems (oEA stars). Analysis of 21 systems with A0-F2 spectral type primaries revealed pulsations in two systems suggesting that of the order of ten persent of Algols primaries in this range are actually pulsators.     

Perspectives for Distributed Observations of Near-Earth Space Using a Russian–Cuban Observatory

The creation of a specialized network of large, wide-angle telescopes for distributed observations of near-Earth space using a Russian–Cuban Observatory is considered. An extremely important goal of routine monitoring of near-Earth and near-Sun space is warding off threats with both natural and technogenic origins. Natural threats are associated with asteroids or comets, and technogenic threats with man-made debris in near-Earth space. A modern network of ground-based optical instruments designed to ward off such threats must: (a) have a global and, if possible, uniform geographic distribution, (b) be suitable for wide-angle, high-accuracy precision survey observations, and (c) be created and operated within a single network-oriented framework. Experience at the Institute of Astronomy on the development of one-meter-class wide-angle telescopes and elements of a super-wide-angle telescope cluster is applied to determine preferences for the composition of each node of such a network. The efficiency of distributed observations in attaining maximally accurate predictions of the motions of potentially dangerous celestial bodies as they approach the Earth and in observations of space debris and man-made satellites is estimated. The first estimates of astroclimatic conditions at the proposed site of the future Russian–Cuban Observatory in the mountains of the Sierra del Rosario Biosphere Reserve are obtained. Special attention is given to the possible use of the network to carry out a wide range of astrophysical studies, including optical support for the localization of gravitational waves and other transient events.     

Possible ancient giant basin and related water enrichment in the Arabia Terra province, Mars

A circular albedo feature in the Arabia Terra province was first hypothesized as an ancient impact basin using Viking-era information. To test this unpublished hypothesis, we have analyzed the Viking era-information together with layers of new data derived from the Mars Global Surveyor (MGS) and Mars Odyssey (MO) missions. Our analysis indicates that Arabia Terra is an ancient geologic province of Mars with many distinct characteristics, including predominantly Noachian materials, a unique part of the highland-lowland boundary, a prominent paleotectonic history, the largest region of fretted terrain on the planet, outflow channels with no obvious origins, extensive exposures of eroded layered sedimentary deposits, and notable structural, albedo, thermal inertia, gravity, magnetic, and elemental signatures. The province also is marked by special impact crater morphologies, which suggest a persistent volatile-rich substrate. No one characteristic provides definitive answers to the dominant event(s) that shaped this unique province. Collectively the characteristics reported here support the following hypothesized sequence of events in Arabia Terra: (1) an enormous basin, possibly of impact origin, formed early in martian history when the magnetic dynamo was active and the lithosphere was relatively thin, (2) sediments and other materials were deposited in the basin during high erosion rates while maintaining isostatic equilibrium, (3) sediments became water enriched during the Noachian Period, and (4) basin materials were uplifted in response to the growth of the Tharsis Bulge, resulting in differential erosion exposing ancient stratigraphic sequences. Parts of the ancient basin remain water-enriched to the present day.     

The Rondonian-San Ignacio Province in the SW Amazonian Craton: An overview

The Rondonian-San Ignacio Province (1.56–1.30 Ga) is a composite orogen created through successive accretion of arcs, ocean basin closure and final oblique microcontinent–continent collision. The effects of the collision are well preserved mostly in the Paraguá Terrane (Bolivia and Mato Grosso regions) and in the Alto Guaporé Belt and the Rio Negro-Juruena Province (Rondônia region), considering that the province was affected by later collision-related deformation and metamorphism during the Sunsás Orogeny (1.25–1.00 Ga). The Rondonian-San Ignacio Province comprises: (1) the Jauru Terrane (1.78–1.42 Ga) that hosts Paleoproterozoic basement (1.78–1.72 Ga), and the Cachoeirinha (1.56–1.52 Ga) and the Santa Helena (1.48–1.42 Ga) accretionary orogens, both developed in an Andean-type magmatic arc; (2) the Paraguá Terrane (1.74–1.32 Ga) that hosts pre-San Ignacio units (>1640 Ma: Chiquitania Gneiss Complex, San Ignacio Schist Group and Lomas Manechis Granulitic Complex) and the Pensamiento Granitoid Complex (1.37–1.34 Ga) developed in an Andean-type magmatic arc; (3) the Rio Alegre Terrane (1.51–1.38 Ga) that includes units generated in a mid-ocean ridge and an intra-oceanic magmatic arc environments; and (4) the Alto Guaporé Belt (<1.42–1.34 Ga) that hosts units developed in passive marginal basin and intra-oceanic arc settings. The collisional stage (1.34–1.32 Ga) is characterized by deformation, high-grade metamorphism, and partial melting during the metamorphic peak, which affected primarily the Chiquitania Gneiss Complex and Lomas Manechis Granulitic Complex in the Paraguá Terrane, and the Colorado Complex and the Nova Mamoré Metamorphic Suite in the Alto Guaporé Belt. The Paraguá Block is here considered as a crustal fragment probably displaced from its Rio Negro-Juruena crustal counterpart between 1.50 and 1.40 Ga. This period is characterized by extensive A-type and intra-plate granite magmatism represented by the Rio Crespo Intrusive Suite (ca. 1.50 Ga), Santo Antonio Intrusive Suite (1.40–1.36 Ga), and the Teotônio Intrusive Suite (1.38 Ga). Magmatism of these types also occur at the end of the Rondonian-San Ignacio Orogeny, and are represented by the Alto Candeias Intrusive Suite (1.34–1.36 Ga), and the São Lourenço-Caripunas Intrusive Suite (1.31–1.30 Ga). The cratonization of the province occurred between 1.30 and 1.25 Ga.     

Sensitivity analysis applied to slope stabilization at failure

This article discusses how sensitivity analysis is a sound assessment tool for selecting the most efficient stabilization method of slopes at failure. A discretized form of the variational approach is used not only for performing sensitivity analysis but to locate the critical slip surface, i.e., the sensitivity analysis is carried out in the same way as it is done in optimization problems. This method supplies a robust formulation and methodology for obtaining the sensitivities of the safety factor with respect to both the soil parameters and the slope profile, stating the slope stabilization design as a relatively simple minimization problem. Two well known examples, as the Selset landslide and the Sudbury Hill slip are used to illustrate the application of the method and to highlight both its capabilities and limitations.     

Wave constraints for Titan’s Jingpo Lacus and Kraken Mare from VIMS specular reflection lightcurves

Stephan et al. (Stephan, K. et al. [2010]. Geophys. Res. Lett. 37, 7104-+.) first saw the glint of sunlight specularly reflected off of Titan’s lakes. We develop a quantitative model for analyzing the photometric lightcurve generated during a flyby in which the specularly reflected light flux depends on the fraction of the solar specular footprint that is covered by liquid. We allow for surface waves that spread out the geographic specular intensity distribution. Applying the model to the VIMS T58 observations shows that the waves on Jingpo Lacus must have slopes of no greater than 0.15°, two orders of magnitude flatter than waves on Earth’s oceans. Combining the model with theoretical estimates of the intensity of the specular reflection allows a tighter constraint on the waves: ?0.05°. Residual specular signal while the specular point lies on land implies that either the land is wetted, the wave slope distribution is non-Gaussian, or that 5% of the land off the southwest edge of Jingpo Lacus is covered in puddles. Another specular sequence off of Kraken Mare acquired during Cassini’s T59 flyby shows rapid flux changes that the static model cannot reproduce. Points just 1 min apart vary in flux by more than a factor of two. The present dataset does not uniquely determine the mechanism causing these rapid changes. We suggest that changing wind conditions, kilometer-wavelength waves, or moving clouds could account for the variability. Future specular observations should be designed with a fast cadence, at least 6 points per minute, in order to differentiate between these hypotheses. Such new data will further constrain the nature of Titan’s lakes and their interactions with Titan’s atmosphere.     

Virtual Coast Guard: An Open and Crowdsourced GIS Portal for Stewardship of India's Coast

India's coastline is under tremendous pressure. The current processes of development are becoming a threat to the ecology and livelihoods housed on the coast. If left unchecked, there will not be much of a coast left for our future generations. GIS provides tremendous opportunities to map spatial information for better decision‐making. Government agencies generate maps, but they are localized and inaccessible, preventing an actual assessment of the damage that is already happening to our coast. The Coastal Area Mapping Project (CAMP) envisions creating a collaborative GIS platform using open source technologies. CAMP's vision is to use Free and Open Source Software (FOSS) for collaboration and cocreation and collective problem solving. CAMP foresees a vision for India's coastline where power is equalized among all constituencies (Government, corporations, media, communities, civil societies, etc.), by capturing the big picture and patterns, thus enabling the creation of strategies for stewardship of India's coastline for human wellbeing, coastal protection and sustainable coastal development.