Chlorophyll concentration and surface temperature changes associated with earthquakes

The preparation process of an impending earthquake may leave fingerprints on the earth??s surface. Elastic strain in rocks, formation of micro-cracks, gas releases and other chemical or physical activities in the earth??s crust before and during earthquakes has been reported to cause rises in temperature, surface latent heat flux (SLHF), upwelling index and chlorophyll-a (Chl-a) concentration on the ground or sea surface. Changes in surface temperature can be monitored with thermal infrared sensors such as NOAA-AVHRR and microwave radiometers like AMSR-E/Aqua. SLHF data and upwelling indices are provided by National Centers for Environmental Prediction (NCEP) Reanalysis Project and Pacific Fisheries Environmental Laboratory, respectively. This study examines behaviors of the above four factors prior to the past three oceanic and coastal earthquakes occurred at the Pacific Ocean (Northern California of June 15, 2005, Central California of September 28, 2004, and December 22, 2003). We were successful in detecting pre-earthquake anomalies prior to all three earthquakes. Our detailed analysis revealed 1?C5?°C rises in surface temperature in epicentral areas. Considerable anomalies in Chl-a concentration, 1?C2?weeks before the day of the main earthquakes, were spotted, which are attributed to the rise in upwelling index. Time series of SLHF showed meaningful rises from 1?month to a fortnight before the earthquake events. One problem in our research was the low resolution of the data which makes the graphs that are generated from NCEP database affected by all sources of anomalies, other than seismic activities, within an about 1.8°?C2.5° (200?km) area.     

Flow units delineation of multiple hydrocarbon reservoirs using hydraulic zonation technique via cluster analysis algorithm,Zeit Bay Field,Gulf of Suez,Egypt

Investigation of hydraulic units in drilled wells through multiple reservoirs in Zeit Bay Field is the main target of this paper. Karim Limestone and Nubian Sandstone are target reservoirs in this study. Hydraulic zones provide a fundamental unit for subsequent reservoir characterization and simulation and also prove to be helpful in defining future well completion and work over practices. Hydraulic zonation by means of cluster analysis has been utilized to achieve this target. Hierarchical cluster analysis, elbow method, and k-means clustering are the main steps of this analysis. Petrophysical properties obtained from cores are utilized to perform this zonation. These properties are permeability and porosity data. Results have been validated by comparing the geological behavior of each zone against the measured permeability curve. Finally through this zonation, flow units which have the potential to extract fluids are determined more accurately. Petroleum geologists and engineers are more interested in these results. The cluster analysis flow suggesting in this paper is cost-effective due to lack of need for any commercial software.     

The vein-type barite mineralization of the Draïssa ore field,Ougarta; SW- Algeria: mineralogy,trace elements and halogens

The Draïssa barite vein system in the Ougarta district is located in southwestern Algeria. It is the principal mineral deposit of economic interest of the area. The mineralization is hosted by Cambrian sedimentary rocks that unconformably overlie Precambrian formations. The mineralized structures consist mostly of barite and quartz with minor sulfide minerals and trend dominantly NE-SW, NW-SE, and E-W. Siliceous alteration zones are associated with the vein system. Samples of barite ore are characterized by low total REE contents ranging from 9 to 50 ppm and positive Eu (2–2.15 ppm) and Y (1.2–11.1 ppm) anomalies, indicating hydrothermal activity during mineralization. Halogen data of the barite show that the Cl/Br molar ratio is 189:571 and the Na/Br ratio is 34:376, indicating that the sulfur was derived from seawater. The Ba-enrichment trend in the volcanic rocks of Draïssa is interpreted as possible probable source of the Ba (424–3039 ppm Ba). It appears that the barite-quartz deposits were formed in two stages. Endogenous fluids deposited the primary vein materials, consisting of quartz associated with copper sulfides. Exogenous fluids (cold seawater) became heated during ascendant fluid movement. Mineralization was governed by convective motions and the barite and galena fillings were deposited in openings created by normal faulting.