Late Palaeozoic NE–SW ductile–brittle extension in the La Serre horst,eastern France

In the La Serre horst of the Alpine foreland, the pre-Triassic La Serre median fault zone separates a Late Devonian–Early Carboniferous granite from an ignimbrite of unknown age and from Permian deposits. Motion along this fault zone took place first in ductile conditions and then evolved in brittle conditions. Both ductile and brittle shear criteria indicate a top-NE normal-dextral displacement. Similar motions are reported along faults bounding Late Palaeozoic intramontane coal basins located in the Massif Central and correspond to a widespread NE–SW Late to Post-Orogenic extension that affected the Variscan basement during Late Carboniferous to Early Permian times. To cite this article: G. Coromina, O. Fabbri, C. R. Geoscience 336 (2004).     

Coastal Precipitation Regimes in Kenya

Kenya is under the influence of the seasonal reversal of the Indian ocean monsoons. However, its coastal belt, up to about 50 km inland, exhibits original climatic features. Hierarchical clustering of mean monthly rainfall for a large number of stations, particularly in the south-eastern region, strongly differentiate a maritime climate characterised by enhanced and delayed "long rains" and no dry season in the northern summer. Most of these rains fall at night or in the morning. Using daily rainfall data and twice-daily surface and upper-air wind observations, monsoon-breeze interactions and their role on April–August coastal precipitation are assessed. Rain spells common to the whole Kenya coast are associated to a slight weakening of the sea breeze, a strong easterly or south-easterly wind anomaly over most of Kenya at around 850–700 hPa, and sea surface temperatures greater than air temperatures.     

Oscarella balibaloi,a new sponge species (Homoscleromorpha: Plakinidae) from the Western Mediterranean Sea: cytological description,reproductive cycle and ecology

A new homoscleromorph sponge species was observed for the first time in 2002 along the coast of Provence (France) and since then, several investigations have been implemented. The new homoscleromorph species is devoid of skeleton and it is thus related to the Oscarella genus. Oscarella balibaloi sp. nov. has been found in several littoral submarine caves of the Western Mediterranean Sea (France and Spain). After several years of monitoring, we show that this sponge is becoming abundant in several locations. The species has a peculiar habit, often overgrowing massive sponges, gorgonians or some erected bryozoans. Oscarella balibaloi sp. nov. is thinly encrusting, with an irregular morphology, lobate surface, and soft and very slimy consistency. Its color is white to orange. At the cytological level, this new species is characterized by three distinct types of cells with inclusions in its mesohyl: one with vacuoles and the others with paracrystalline inclusions. The reproduction pattern is very similar to other Oscarella species. We also present a specific metabolic fingerprint and compare it to that of other Mediterranean Oscarella species.     

Display-sites selection by houbara bustard (Chlamydotis [undulata] macqueenii) in Mori, Xinjiang, People''s Republic of China

Display-site selection by houbara bustards was studied in Mori, Xinjiang, China during the breeding seasons from April to June 2000. Most of the habitats chosen for displaying were short sub-shrubby and open areas close to high shrub patches. The displaying males clearly prefer low covered areas and avoid densely covered and high vegetation sites. The vegetation density and number of plant species at display sites were significantly lower from that at randomly selected sites. The average distance to the closest shrub patch was significantly shorter at display sites than at random sites. Plant species richness, vegetative density, vegetative cover and distance to the shrub patches are possibly the most important factors that determined the display-sites selection of houbara bustard.     

Impact of the LMDZ atmospheric grid configuration on the climate and sensitivity of the IPSL-CM5A coupled model

The IPSL-CM5A climate model was used to perform a large number of control, historical and climate change simulations in the frame of CMIP5. The refined horizontal and vertical grid of the atmospheric component, LMDZ, constitutes a major difference compared to the previous IPSL-CM4 version used for CMIP3. From imposed-SST (Sea Surface Temperature) and coupled numerical experiments, we systematically analyze the impact of the horizontal and vertical grid resolution on the simulated climate. The refinement of the horizontal grid results in a systematic reduction of major biases in the mean tropospheric structures and SST. The mid-latitude jets, located too close to the equator with the coarsest grids, move poleward. This robust feature, is accompanied by a drying at mid-latitudes and a reduction of cold biases in mid-latitudes relative to the equator. The model was also extended to the stratosphere by increasing the number of layers on the vertical from 19 to 39 (15 in the stratosphere) and adding relevant parameterizations. The 39-layer version captures the dominant modes of the stratospheric variability and exhibits stratospheric sudden warmings. Changing either the vertical or horizontal resolution modifies the global energy balance in imposed-SST simulations by typically several W/m² which translates in the coupled atmosphere-ocean simulations into a different global-mean SST. The sensitivity is of about 1.2 K per 1 W/m² when varying the horizontal grid. A re-tuning of model parameters was thus required to restore this energy balance in the imposed-SST simulations and reduce the biases in the simulated mean surface temperature and, to some extent, latitudinal SST variations in the coupled experiments for the modern climate. The tuning hardly compensates, however, for robust biases of the coupled model. Despite the wide range of grid configurations explored and their significant impact on the present-day climate, the climate sensitivity remains essentially unchanged.     

Is the instrumental drift of superconducting gravimeters a linear or exponential function of time?

The instrumental drift of the superconducting gravimeter in Membach, Belgium, is estimated using 9 years of co-located and episodic absolute gravity measurements. We show that the best model of the long-term drift of the SG-C021 is an exponential. The thermal levelers used to compensate tilts are unlikely to induce the observed drift. Rather, the capacitance bridge, magnetic variations, gas adsorption on the levitating sphere, or helium gas pressure variations around it are most likely the possible combined causes of the observed instrumental drift. In practice, either linear or exponential drift models are equivalent as long as the record duration does not exceed 10 years. For longer records, this study demonstrates that an exponential models the drift better than a simple linear trend.     

Assessing physical vulnerability in large cities exposed to flash floods and debris flows: the case of Arequipa (Peru)

Understanding the physical vulnerability of buildings and infrastructure to natural hazards is an essential step in risk assessment for large cities. We have interpreted high spatial resolution images, conducted field surveys, and utilized numerical simulations, in order to assess vulnerability across Arequipa, south Peru, close to the active El Misti volcano. The emphasis of this study was on flash floods and volcanic or non-volcanic hyperconcentrated flows, which recur on average every 3.5 years across the city. We utilized a geographic information system to embed vulnerability and hazard maps as a step to calculate risk for buildings and bridges along the Río Chili valley and two tributaries. A survey of ~1,000 buildings from 46 city blocks, different in age, construction materials, and land usage, provided architectural and structural characteristics. A similar survey of twenty bridges across the three valleys was based on structural, hydraulic, and strategic parameters. Interpretation of high spatial resolution (HSR) satellite images, which allows for quick identification of approximately 69 % of the structural building types, effectively supplemented field data collection. Mapping vulnerability has led us to pinpoint strategic areas in case of future destructive floods or flows. Calculated vulnerability is high if we examine structural criteria alone. We further consider physical setting with the most vulnerable city blocks located on the lowermost terraces, perpendicular or oblique to the flow path. Statistical analysis conducted on 3,015 city blocks, considering nine criteria identified from HSR images, indicated that building-type heterogeneity and the shape of the city blocks, along with building and street network density, are the most discriminant parameters for assessing vulnerability.     

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