Quality of GPS point positioning by TI 4100 receiver

The quality of absolute positioning by the Global Positioning System, using the TI 4100 receiver is investigated. Using 30 min of pseudo-range measurements, the derived coordinates of four tracking stations are estimated with standard errors of the order of 1–9 m. The paper points out that point-positioning users should be aware of the quality of positions and to some extent of the various sources of error.     

Static deformation of two welded half-spaces due to very long strike-slip dislocations

Closed form analytic expressions for displacement and stresses at any point of either of the two homogeneous, isotropic, perfectly elastic half-spaces in welded contact due to very long strike-slip dislocations are obtained. Both cases of vertical and horizontal strike-slip dislocations are discussed in detail. Variation of the displacement with horizontal distance from the fault and with vertical distance from the interface for a vertical strike-slip fault is studied numerically.     

A structural synthesis of the Proterozoic Arabian-Nubian Shield in Egypt

Detailed structural geological and related studies were carried out in a number of critical areas in the Proterozoic basement of eastern Egypt to resolve the structural pattern at a regional scale and to assess the general characteristics of tectonic evolution, orogeny and terrane boundaries. Following a brief account of the tectonostratigraphy and timing of the orogenic evolution, the major structural characteristics of the critical areas are presented. Collisional deformation of the terranes ended about 615-600 Ma ago. Subsequent extensional collapse probably occurred within a relatively narrow time span of about 20 Ma (575 – 595 Ma ago) over the Eastern Desert and was followed by a further period of about 50 Ma of late to post-tectonic activity. The regional structures originated mainly during post-collisional events, starting with those related to extensional collapse (molasse basin formation, normal faulting, generation of metamorphic core complexes). Subsequent NNW-SSE shortening is documented by large-scale thrusting (towards the NNW) and folding, distributed over the Eastern Desert, although with variable intensity. Thrusts are overprinted by transpression, which was localized to particular shear zones. Early transpression produced, for example, the Allaqi shear zone and final transpression is documented in the Najd and Wadi Kharit-Wadi Hodein zones. Two terrane boundaries can be defined, the Allaqi and South Hafafit Sutures, which are apparently linked by the high angle sinistral strike-slip Wadi Kharit-Wadi Hodein shear zone with a tectonic transport of about 300 km towards the W/NW. In general, the tectonic evolution shows that extensional collapse is not necessarily the final stage of orogeny, but may be followed by further compressional and transpressional tectonism. The late Pan-African high angle faults were reactivated during Red Sea tectonics both as Riedel shears and normal faults, where they were oriented favourably with respect to the actual stress regime.     

Strike slip faulting inferred from offsetting of drainages: Lower Narmada basin, western India

The detailed analysis of landforms, drainages and geology of the area between the rivers Amaravati and Karjan was carried out in order to understand the tectonic history of the lower Narmada basin. Movement along the various faults in the area was studied on the basis of the drainage offsetting. Horizontal offsetting of stream channels was found quite demonstrable along NNW-SSE trending transverse faults. Tectonic landforms including systematic deflection of stream channels and ridges, alignment of fault scarp and saddles and displacement in the basement rocks and alluvial deposits show that the area is undergoing active deformation driven by the NSF system.     

An Experiment Using the High Resolution Eta and WRF Models to Forecast Heavy Precipitation over India

In the present study using the Weather Research and Forecasting (WRF) and Eta models, recent heavy rainfall events that occurred (i) over parts of Maharastra during 26 to 27 July, 2005, (ii) over coastal Tamilnadu and south coastal Andhra Pradesh during 24 to 28 October, 2005, and (iii) the tropical cyclone of 30 September to 3 October, 2004/Monsoon Depression of 2 to 5 October 2004, that developed during the withdrawal phase of the southwest monsoon season of 2004 have been investigated. Also sensitivity experiments have been conducted with the WRF model to test the impact of microphysical and cumulus parameterization schemes in capturing the extreme weather events. The results show that the WRF model with the microphysical process and cumulus parameterization schemes of Ferrier et al. and Betts-Miller-Janjic was able to capture the heavy rainfall events better than the other schemes. It is also observed that the WRF model was able to predict mesoscale rainfall more realistically in comparison to the Eta model of the same resolution.     

Cryptosporidium Oocysts in Drinking Water Supply of Chennai City,Southern India

Cryptosporidium is an enteric parasitic protozoan capable of causing chronic diarrhea. One of the most common modes of transmission is through faeces‐contaminated water. This study determines the distribution of Cryptosporidium oocysts for the first time in Chennai City's drinking water supply. 199 drinking water samples were collected from ten zones of the city. In the water samples Cryptosporidium, a common pathogenic protozoan of the gastrointestinal tract, has been analyzed physico chemically as well as microbiologically for heterotrophic organisms and total coliforms (TC). The studies revealed that three zones of the city were highly contaminated with coliforms and parasitic protozoa. A statistical analysis was done to find any correlation between heterotrophic organisms, total coliforms, and oocysts. Even though a positive correlation exists between oocysts and bacteriological parameters, a regression equation shows that heterotrophic plate count (HPC) and total coliforms were only 20% responsible for the presence of oocysts. The level of Cryptosporidium oocysts isolated from the water samples may present a public health hazard although no major outbreaks have so far been reported in Chennai City. Routine surveillance of water quality throughout the city is needed to curb the pollutants.     

Lineaments and seismicity of Kerala — a remote sensing based analysis

Seismically active lineaments of Kerala State were identified by correlating the lineaments mapped using IRS LISS-I data with the earthquake occurrences. There are 31 earthquake incidences in Kerala since 1821, out of which 22 are falling on/close to 9 major lineaments/faults (length more than 20 km) indicating the possible correlation between lineaments/faults and earthquakes. It was observed that the earthquake occurrences are mostly associated with the NNW-SSE to NW-SE trending lineaments (6 out of 9 lineaments), which are considered to be formed sympathetic to the West Coast Fault. Hence, there is a need to monitor these seismically active lineaments using advanced techniques such as GPS, SAR Interferometry etc. for better understanding of the influence of these lineaments on the seismic activities of Kerala.     

Hydrogeologic Units Of Lebanon

Based on geomorphologic and hydrogeologic characteristics of its territory, Lebanon is divided into three provinces: the West Lebanon province, the Bekaa province, and the East Anti-Lebanon province. These provinces are subdivided into smaller hydrogeologic units, the basins and subbasins. Significant features used in the subdivision are faults, relief, anticlinal axes, river channels, and water divides. Recharge to groundwater is a percentage of the intake area, the percipitation rate over this area, and the infiltration rate of outcropping rocks. The amounts of recharged water over the three provinces are 1609, 914, and 19 Mm³, respectively. Discharge is surface water from springs and water wells along the Lebanese coast. The discharge from the Lebanese rivers exceeds 3700 Mm³/year, an appreciable amount of which comes from natural springs. The quantity of groundwater pumped by wells or flowing into neighboring countries and to the sea as submarine springs, may exceed 800 Mm³/year.     

Geochemical Aspects of Hypogene Hydrothermal Alteration Zones in the Chol-qeshlaghi Area, NW Iran: Constrains on REEs

Chol-qeshlaghi altered area lies in the northwestern part of the post-collisional Urumieh-Dokhtar magmatic arc, NW Iran. Pervasive silicic, argillic, phyllic and propylitic altered zones appears to be intimately affiliated to the fluids derivative of upper Oligocene Khankandi granodiorite. This paper is dedicated to the identification of geochemical characteristics of hydrothermal alterations, focusing on the determination of the mass gains and losses of REEs, to gain significant insights regarding the chemical exchanges prevailed between the host rocks and hydrothermal fluids. The low pH and high activity of SO_4~(-2) ligands in silicic alteration fluids, resulting in depletion of entire REEs. Decreasing of LREEs appeared in argillic zone may attributed to reduce in adsorption ability of clay minerals in low pH; whereas HREEs enrichment in phyllic zone was inclined to put it down to the abundance of sericite(± Fe oxides). A significant reduction of Eu/Eu* ratio in silicic zone can be attributed to negligible sulfides and clay minerals as some effective agents in adsorption of released Eu~(+2). Factors such as changes in pH, the abundance of absorptive neomorph mineral phases, activity of ligands play an important role in controlling the distribution and concentration of REEs in Chol-qeshlaghi alteration system.     

An analytical source function for a coupled hybrid wave model

An analytical form for the source function is formulated by comparing the fetch-limited approximation of the Ocean Wave Transport equation and the empirical equation for the fetch-dependent wave forecast nomograms. The source function thus generated has been utilised in the numerical model based on Toba’s formulation of wave transport equation and tested for the seas around the Indian subcontinent (5°S to 25°N latitude; 45°E to 100°E longitude). The grid averaged hindcast wave heights are found to be moderately matching with the GEOSAT altimeter measured significant wave heights of the 1987–1989 period, particularly for waves higher than 1 meter.