Spatial and temporal variations of atmospheric aerosol optical thickness in northwestern Mexico

The purpose of this paper was to study aerosol particles in the Northwestern region of Mexico (NWM) through Aerosol Optical Thickness (AOT) parameter in the atmosphere. This parameter represents one of the extinction coefficients of solar radiation and the rate of suspended particles in the atmosphere. For determination of AOT, we considered the use of remote sensors outside of the atmosphere. In particular, Moderate Resolution Imaging Spectroradiometer (MODIS) which can measure the atmospheric AOT thickness. Data from the MODIS sensor must be validated before they are considered reliable. For this task, we required surface measurements to obtain a correlation with the data acquired with the remote radiometer. The paper describes the validation process performed for data obtained with MODIS through measurements provided by an AErosol RObotic NETwork (AERONET) photometer located in the city of Hermosillo, Sonora, NWM. Additionally, we carried out a temporal analysis based on the behavior of the AOT graphics and spatial analysis supported in maps with sufficient information.     

A local spatial decision support system for developing countries based on MCA,fuzzy sets and OWA – case study of a municipality in Cuba

This paper presents a Spatial Decision Support System for local governments of developing countries. It allows municipality government, enterprises, scientific community and civil society to address decision problems using GIS. The framework is supported by four modules of information technologies: Environmental Decision Support Database, Data Manipulation, Decision Support, and Mapping. A case study is presented covering the implementation of this framework in one municipality of Cuba. An example of land suitability planning for coconut crops is used to evaluate the system performance and usability. Results show local municipalities are able to use this framework to solve local decision problems using state of the art decision making even with low infrastructure development.     

On the landslide event in 2010 in the Monarch Butterfly Biosphere Reserve, Angangueo, Michoacán, Mexico

In February 2010, 19 fatalities and economic damage were caused by a regional landslide episode in the state of Michoacán, México. The municipalities of Angangueo, Ocampo, Tiquicheo de Nicolás Romero, Tuxpan, and Tuzantla were severely damaged, with Angangueo being the most affected. The event involved a series of debris flows, of which four were the most significant; these four caused 16 deaths in addition to considerable damage to roads, electricity, and the water supply system, with indirect consequences in crop production, cattle farming, and tourism. The area affected by these four flows was calculated as 282?km², with an estimated 697,346?m³ of mobilized material. General observations indicated that the initiation sources of the debris flows were on deforested zones. The present research is concentrated on the Angangueo basin, an area situated within the Monarch Butterfly Biosphere Reserve. Given the lack of rain gauges in the area of interest, records from neighboring points were used to build a comprehensive overview of the extreme precipitation event that triggered the devastating debris flows. The nearest rain gauge, Laguna del Fresno, situated 21?km to the south, recorded 204?mm of rainfall from 1 to 5 February, equivalent to 30% of the mean annual rainfall. Moreover, during a 24-h period the El Bosque rain gauge recorded 144.5?mm of precipitation, the equivalent of 2,270% of the mean rainfall for the same month (6.36?mm). The occurrence of a hailstorm preceding the rainfall event is notable; conditions in the superficial soil layer would have included an increased pore water pressure. Presumably, before the 2,000-year return period extreme rainfall event, thawing of hail and consequent moisture and/or pore-pressure increase result in decreased frictional strength. This paper presents a spatial analysis of the distribution of these landslides, mainly debris flows, as well as general observations on the triggering mechanism, the strength properties of the materials involved, and the societal impact.     

The solubility of aragonite in seawater at 25.0°C and 32.62‰ salinity

The apparent solubility product of aragonite in 32‰ seawater at 25.0°C is reported as K′_sp = (0.869±0.049) × 10^?6(mol²kgseawater^?2) thus confirming the value of R.A. Berner, 1976 (Am. J. Sci., 276: 713–730). The apparent solubility product ratio for aragonite and calcite is reported as $\text{K′}{}_{\mathrm{aragonite}}\text{K′}{}_{\mathrm{calcite}}\text{= 2.05}$ The deviation of this value from the thermodynamic ratio is atttributed to the formation of a stable low Mg-calcite coating on pure calcite in seawater measurements of solubility.     

Decision support for conceptual performance‐based design

Performance assessment implies that the structural, non‐structural, and content systems are given and that decision variables, DVs, (e.g. expected annual loss, mean annual frequency of collapse) are computed and compared to specified performance targets. Performance‐based design (PBD) is different by virtue of the fact that the building and its components and systems first have to be created. Good designs are based on concepts that incorporate performance targets up front in the conceptual design process, so that subsequent performance assessment becomes more of a verification process of an efficient design rather than a design improvement process that may require radical changes of the initial design concept. In short, the design approach could consist of (a) specifying performance targets (e.g. tolerable probability of collapse, acceptable dollar losses) and associated seismic hazards, and (b) deriving engineering parameters for system selection, or perhaps better, using the relatively simple design decision support tools discussed in this paper. Copyright © 2005 John Wiley & Sons, Ltd.     

Ordovician K-bentonites in the upper-plate active margin of Western Gondwana, (Famatina Ranges): Stratigraphic and palaeogeographic significance

Numerous, thin-bedded, tabular pale-yellowish clay bands are interlayered with black shales in a biostratigraphically constrained Early Ordovician volcano-sedimentary succession at Famatina, western Argentina. This region was part of a fairly continuous upper-plate, convergent volcanic chain that fringed western Gondwana. Mineralogy on both clay and non-clay fractions, whole rock chemistry and field observations on these distinctive event-beds indicate that they originated as relatively coarse fallout tephras, altered first into bentonites and later, through burial metamorphism, into K-bentonites (metabentonites). These tephras were deposited as single crystals and glassy dust or pumiceous fragments in a restricted subtidal environment. The region of Famatina has previously been inferred as the source of abundant distal K-bentonites recorded in the adjacent lower-plate allochthonous Precordillera terrane. However, these K-bentonites within the proximal arc site were unknown and rather unexpected since they are generally better preserved like distal deposits, associated either with central vent plinian–ultraplinian eruptions or with accompanying co-ignimbrite ash clouds. Their chemistry and comparison with those K-bentonites in the Precordillera allow tracing an evolution from volcanic arcs into continental crust. K-bentonites described in this paper are much older than those recorded in the adjacent Precordillera terrane and seem to be associated with a first eruptive period along western Gondwana that has no counterpart in the Argentine Precordillera, suggesting a significant longitudinal separation between these two regions by the Early Ordovician.     

Geologic and tectonic setting of Deseado Massif epithermal deposits, Argentina, based on El Dorado-Monserrat

Middle–Late Jurassic bimodal volcanism, typical of a retroarc setting, developed during widespread extensional tectonism within the Deseado Massif, southern Argentina. This geologic environment led to the formation of numerous low-sulfidation epithermal deposits that are spatially and temporally related to the volcanic activity. The lack of significant high-sulfidation epithermal deposits may be because the tectonic and volcanic settings do not favor the formation of these types of deposits. El Dorado-Monserrat is a low-sulfidation epithermal prospect located near the southern boundary of the Deseado Massif. Mineralization is genetically linked to the Late Jurassic Chon Aike Formation and hosted by volcanic rocks of the middle Late Jurassic Bajo Pobre Formation. Two different mineralization areas have been identified. The Monserrat area is the most important, with veins hosted in a north-striking, left-lateral shear zone. The average thickness is 0.85 m, and the average metal content is 6.2 ppm gold and 153 ppm silver. The El Dorado area has discontinuous echelon veins within a right-lateral shear zone with low gold and silver grades. Hydrothermal alteration of the host rocks includes an inner zone of quartz-adularia and illite alteration and an outer zone of propylitic alteration. The main gangue mineral is quartz, which formed in successive pulses, plus adularia, pyrite, hematite, magnetite, and barite. Precious metals occur as zoned electrum. Ore mineral precipitation took place between 200 and 280 °C from low salinity fluids due to boiling.