Patagonia, including the island of Tierra del Fuego, lies in southernmost South America at the junction of the South American,
Antarctic, and Scotia tectonic plates. Historical and instrumental records have documented several local earthquakes of damaging
magnitude, posing a threat to the rapidly growing population of 300,000 and the expanding industrial and service infrastructure.
Short and inaccurate instrumental records of local seismic events and a diffuse epicenter distribution not clearly related
to the recognized seismogenic structures have hindered an adequate evaluation of the seismic hazard for this region. To improve
this situation, a paleoseismological study was carried out on two gravelly strandplains on the Atlantic coast of Patagonia.
Surveying combined ground-probing radar, vertical electric sounding, and seismic refraction. Coseismic normal faults buried
beneath the strandplain bodies were revealed and related to the morphology of the strandplains. The faults have probable ages
between 0.9 and 6.4 kyr BP and a recurrence rate of about 1 kyr. The more likely source for these structures is the Magallanes-Fagnano
fault, a continental transform fault that crosses Tierra del Fuego. The distance of more than 300 km from the buried coseismic
structures to the trace of the Magallanes-Fagnano fault argues for high-magnitude earthquake activity on this fault throughout
the Holocene. Urban development on soft glacial and alluvial substrates increases the hazard. 相似文献
Measurement of solar radiation was initiated in Girona, northeast of the Iberian Peninsula, in the late 1980s. Initially, two pyranometers were installed, one of them equipped with a shadowband for measuring the diffuse component. Two other pyranometers currently exist, both ventilated and one of them shadowed, with a sphere, and a pyrheliometer for measuring direct radiation. Additional instruments for other shortwave and longwave components, clouds, and atmospheric aerosols have been installed in recent years. The station is subject to daily inspection, data are saved at high temporal resolution, and instruments are periodically calibrated, all in accordance with the directions of the Baseline Surface Radiation Network. The present paper describes how the entire series of global solar radiation (1987–2014) and diffuse radiation (1994–2014) were built, including the quality control process. Appropriate corrections to the diffuse component were made when a shadowband was employed to make measurements. Analysis of the series reveals that annual mean global irradiance presents a statistically significant increase of 2.5 W m−2 (1.4 %) decade−1 (1988–2014 period), mainly due to what occurs in summer (5.6 W m−2 decade−1). These results constitute the first assessment of solar radiation trends for the northeastern region of the Iberian Peninsula and are consistent with trends observed in the regional surroundings and also by satellite platforms, in agreement with the global brightening phenomenon. Diffuse radiation has decreased at −1.3 W m−2 (−2 %) decade−1 (1994–2014 period), which is a further indication of the reduced cloudiness and/or aerosol load causing the changes.
Earth observation satellites produce large amounts of images/data that not only must be processed and preserved in reliable geospatial platforms but also efficiently disseminated among partners/researchers for creating derivative products through collaborative workflows. Organizations can face up this challenge in a cost-effective manner by using cloud services. However, outages and violations of integrity/confidentiality associated to this technology could arise. This article presents FedIDS, a suite of cloud-based components for building dependable geospatial platforms. The Fed component enables organizations to build shared geospatial data infrastructure through federation of independent cloud resources to withstand outages, whereas IDS avoids violations of integrity/confidentiality of images/data in sharing information and collaboration workflows. A FedIDS prototype, deployed in Spain and Mexico, was evaluated through a study case based on a satellite imagery captured by a Mexican antenna and another based on a satellite imagery of a European observation mission. The acquisition, storage and sharing of images among users of the federation, the exchange of images between Mexican and Spanish sites and outage scenarios were evaluated. The evaluation revealed the feasibility, reliability and efficiency of FedIDS, in comparison with available solutions, in terms of performance, storage consume and integrity/confidentiality when sharing images/data in collaborative scenarios. 相似文献
The potential of Mexico for placer minerals in beach sediments has been analyzed, taking into consideration the geomorphic, tectonic, and lithologic conditions of nine different coastal regions. Besides, the textural characteristics of average size and degree of classification, carbonate content was also considered as a measure of terrigenous influence. It is concluded that mineral bearing rocks in the source area, and well-classified fine sands, poor in carbonates, in the beach area represent the major potential for placer minerals. Favorable conditions for placer minerals may be present in Regions 2 and 3 in the Central and Southern portion of the Gulf of Mexico coast, and have their highest potential in Regions 6, 7, 8, and 9 in the Gulf of California and along the Western mainland coast from the Colorado River in the North to the Guatamalan border in the South. 相似文献
Recent studies have shown the value of place names as environmental indicators. Until now they have not been applied to the effects of climate change, because verifying such relationship by this approach requires a multidisciplinary analysis and a study area where the anthropic impact has been recent. This study aims to test the possibility in a study area little altered by man until the second half of the twentieth century (Doñana Natural Park, SW Spain), and with a heritage very rich in wetlands. The results show that the desiccation of these wetlands is reflected in the local toponymy, and that in turn this regression is related with the end of the Little Ice Age and with the beginning of warming in southern Europe during the twentieth century. The coincidence of these results with data published for Arctic latitudes reveals—in our opinion—the possibility that certain place names can be used as indicators of recent climate changes, at least in some ecosystems. 相似文献
Contamination from the use of chlorinated solvents, often classified as dense nonaqueous phase liquids (DNAPLs) when in an undissolved state, represents an environmental challenge with global implications. Mass-transfer limitations due to rate-limited dissolution can lead to long-term aquifer persistence for even small volumetric fractions. The identification of DNAPL source zones located beneath the water table is critical to ultimately achieve site remediation and aquifer restoration. This paper provides a comparison of the advantages and disadvantages of many of the methods being used for detecting and delineating DNAPL contaminant source zones. The objective is to determine which options are best to pursue based on site characteristics, method performance, and method costs. DNAPL characterization methods are grouped into approaches, which include site preparation, characterization, and data-processing activities necessary to design an effective remediation system. We compare the different approaches based on the level of chemical and hydrogeologic resolution, and the need for additional data requirements. Our findings can be used to assist with selection of appropriate site remediation management options. 相似文献
Mexico City is the largest city in population and area in the world. In the last 30 years it has expanded its area westwards to include the mountains of the Sierra de las Cruces. These mountains contain the nearest forest reserve for the citizens of Mexico City. Deforestation and severe ecological degradation resulting from the destruction of the natural environment; air, water and soil pollution; and hydrological and geomorphological imbalances, limit the capacity of these areas to support forest regeneration. This study focuses on the geo-ecology of the climax oak woodlands found in the Sierra de las Cruces. Based on morpho-structural evidence, bioclimatic type, degree of human intervention and general geo-ecological considerations, three territorial systems have been differentiated in which the oak woodlands exist in different climax facies: a) oak woodlands developed in very humid and cool environments located on low mountain slopes; b) disturbed oak woodlands developed in humid and cool environments located on high piedmonts; and c) highly disturbed oak woodlands developed in subhumid and temperate environments, located on low piedmonts. A comparative study of the content, structure and functional relationships of the secondary facies associated with these climax communities, allowed conclusions to be drawn on the way oak woodlands respond to human intervention, and the risky situations to which these communities are subjected, particularly the most sensitive facies that deserve immediate protection. 相似文献
Zusammenfassung Im Rahmen einer weiträumigen geologischen Kartierung für das Instituto de Investigaciones Geológicas wurde 1956 direkt östlich der Oase Quillagua in Nordchile eine sehr auffallende Kratergruppe entdeckt und photogeologisch ausg 相似文献
The Upper Miocene and Pliocene evaporite deposits of the Atacama Desert of northern Chile (Hilaricos and Soledad Formations) are among the few non‐marine evaporites in which aridity not only formed the deposits, but has also preserved them almost unaltered under near‐surface conditions. These deposits are largely composed of displacive Ca sulphate and halite together with minor amounts of glauberite, thenardite and polyhalite. However, at the base and top of these deposits, there are also beds of gypsum crystal pseudomorphs that originally formed as free‐growth forms within shallow brine bodies, rather than as displacive sediments. The halite is present as interstitial cement, displacive cubes and shallow‐water, bottom‐growth chevron crusts. Most of the calcium sulphate is presently anhydrite, pseudomorphous after gypsum, that was the primary depositional sulphate mineral. The secondary anhydrite formed under early diagenetic conditions after slight burial (some metres) resulting from the effect of strongly evolved pore brines. The anhydrite has been preserved without rehydration during late diagenetic and exhumation stages on account of the arid environment of the Atacama Desert. Both the Hilaricos and the Soledad Formations contain geochemical markers indicating that these Neogene evaporites had a largely non‐marine origin. Bromine content in the halite is very low (few p.p.m.), indicating neither a sedimentological relation with sea water nor the likelihood of direct recycling of prior marine halites. Moreover, the δ34S of sulphates (+4·5‰ to +9‰) also reflects a non‐marine origin, with a strong volcanic influence, although some recycling of Mesozoic marine sulphates cannot be ruled out. δ34S of dissolved sulphate from hot springs and streams in the area commonly displays positive values (+2‰ to +10‰). Leaching of oxidized sulphur and chlorine compounds from volcanoes and epithermal ore bodies, very common in the associated drainage areas, have been the main contribution to the accumulation of evaporites. The sedimentary and diagenetic evolution of the Hilaricos and Soledad evaporites (based on lithofacies analysis) provides information about the palaeohydrological conditions in the Central Depression of northern Chile during the Neogene. In addition, the diagenesis and exhumation history of these evaporites confirms the persistence of strongly arid conditions from Late Miocene until the present. A final phase of tectonism took place permitting the internal drainage to change and open to the sea, resulting in dissolution and removal of a significant portion of these deposits. Despite the extensive dissolution, the remaining evaporites have undergone little late exhumational hydration. 相似文献