JOURNAL OF THE EARTH
Year:2010 | Volume:5 | Issue:2|Papers Count:14

Estimation of site response from an earthquake is fundamental step to anticipate the possible damages and so the objective of a site response analysis is to estimate the ground shaking during an earthquake. In this paper the effect of nonlinearity on site response analyses summarized and evaluating ground surface response taking into account the local soil and subsurface soils properties for the proposed bridge at Sirdjan Balvavard road subjected to earthquake provokes with Standard Hyperbolic Model for nonlinear condition was executed. This area is prone to high seismic risk due to the presence of several active faults and therefore quantifying the site effect on the surface over a number of geotechnical areas has been notified. For site characterization, deep site investigations have been undertaken, and a seismic geotechnical procedure has proposed. The effect of nonlinearity on site response analysis for the selected site with assumption of elastic and rigid half space bedrock by use of Standard Hyperbolic Model was evaluated and the results of them over a number of geotechnical areas were compared to each other. Critical point of this work was to design, develop and use a seismic geotechnical based computer code by authors which named as "Abbas Converter". It has several advantages, which can make facilitate this study more than previous have done and take over the encountered problem. This study clearly showed the applicability of "Abbas Converter" on evaluation of site response with bedrock type assumption on soil behavior under the earthquake excitations.

Choqa Zanbil is a historical district which located at 48o 30' northern latitude and 32o 00' eastern longitude at southwest of Iran, Khozestan Province and southeast of ancient city of Shoush.Choqa Zanbil temple which is the largest remained architecture record of Eilami Civilization was built on Sardar Abad Anticline at 3th century b.c. which located inside Folded Zagross Zone. Rock outcrops at the area are parts of Gachsaran, Mishan and Aghajari formations and Quaternary Bakhtiari Conglomerates and alluviums.Low calculated Sl values (10) in Valley of Dez River point to faulting process. During this activity, usually transversal faults caused to fragmentation of rocks, so rivers flow in subdued valleys.High calculated Sl values (50) on floppy rocks at southeastern part of the anticline show recent tectonic activities which are more stronger related to northwestern part of temple building.Performed studies show second class "Relative Tectonic Activities" for the forehead of main mountains of the area, which demonstrated the temple didn’t demolish by tectonic processes through time.However, relocation in second and third enclosures of the temple points to the act of Quaternary dip-slip sinistral and dextral faults at the area.

Reservoir Characterization is a process which leads to increasing the final reserve of an oil field recovery. Petrophysical Evaluation and reservoir characterization is one of studies which being applied for this reason. In this study, Sarvak and Ilam Formations from Bangestan Group have been investigated by petrophysical studies. all the petrophysical calculations has been made by Geolog 6.6. In this project the deterministic method was used for interpretation of logs. For this purpose after editing and applying proper corrections on petrophysical logs, finally, petrophysical parameters such as porosity, volume shale, water saturation and lithology being generated to evaluate, investigate and interpret of two reservoir horizon of Sarvak and Ilam in wells No.1 and 2.

The Ruteh Formation in northeast of Baladeh village, Central Alborz has 259 m thickness and can be subdivided into five lithological units. This formation overlies unconformably the Dorud Formation and is covered non-conformably by the Nessen Formation. The Ruteh Formnation in studied section consists of gray, medium to thick-bedded cliff-forming limestones with intercalations of thin-bedded shales and marls, and massive basalts (60 m) at the top. In the present study, according to stratigraphical distribution of microfauna' s investigationLangella-Globivalvulina Assemblage Zone (Early Murgabian) for lithological unit 1 andNeoendothyra-Pachyphloia Assemblage Zone (Late Murgabian) for lithological units 2-4 of the Ruteh Formation are established.

In this research which is done for the purpose of exploration, we try to specify the effective criteria in knowing the mineralogy by using study tools and new methods in order to use them for identifying the mineral potentials.Present studies are geology studies and preparing geology and alteration map in north and north–west of Ahar in Kighal area with an area of 12 km2 and a scale of 1: 5000.The lithologic units of area are igneous volcanic and sub-volcanic rocks which have been formed in eocene to quaternary periods that included andesit, tuff, agglomerate, tracy-basalt and intrusive rocks of porphyritic granodiorite and porphylitic monzodiorite with nature of sub-volcanic, and lavas and basic volcano domes of plio- quaternary with compositions of basalt and andesite.Alteration in this area are related to activity of hydrothermal fluids resulting from intrusion of oligocene sub-volcanic rocks with composition of granodiorite in north-east and monzonite, dacite and riolite in west of area and numerous dikes have been occurred that north-eastern part of Kighal is considered as the most important restricted area from the view point of mineralization. This alteration is included propylitic, argilic, advance argilic, serisitic and potasic that have same zoning with porphyritic systems in the area's alterations and the presence of mineral creation of ore copper as stockwork in potasic zone in these alterations are helpful evidence which are vigorated the probability of the presence of porphyritic system in this area.

Now a days, the evaluation of reservoir rocks has special importance in oil industry. The ability of petrophysics and petrography methods as complement of each others have specific importance to find reservoir zones and studies of them in petroleum geology. In this paper we attempted to evaluating Asmari Formations in Ahwaz sandstone member (Ghar) and the carbonate Asmari aspect of development of reservoir properties. For this purpose we used reservoir properties such as porosity, water saturation, volume of shale and lithology has been evaluated using log data and combining of this information with petrography studies. Based on petrophysical properties variations, and petrography studies, 5 petrophysical zones in the Ghar reservoir and 6 petrophysical zones in the Asmari reservoir have described. The result of this studies show based on petrophysical properties distribution, the central area of field is the best area for drilling the developmental wells.

In this study based on the geology of targeted horizons, some horizon attributes like dip and azimuth were generated and evaluated. These attributes were used to detect faults and fractures over the 3D survey area. A complex trace analysis was also conducted on Inline 621, which passes through well No.6. Several instantaneous attributes were generated in an attempt to relate to reservoir or hydrocarbon characteristics and also to aid in time horizon correlations in poor data areas. Based on achieved results on dip, amplitude, width attributes 3 major fault were recognized. In deeper parts like Sarvak and Fahliyan, these attributes are indicating some stratigraphic features.

Study area is located in 130 km Southeaster of Damghan city and North of the Jandagh desert between Torud- Moalleman villages. This area situated in Central Iran zone and located between two major faults, Torud fault in South and Anjilu fault in North. This region belongs to Torud-Chahshirin volcano-plutonic band with metamorphic substructure. Volcanic rocks of this area consist of dacite, andesit, trachyandesit, tuff, rhyodacite, rhyolite and andesibasalt also the plutonic rocks consist of Granite and Granodiorite to Diorite. The Paleozoic and Mesozoic sedimentary rocks separated in west of this area. These rocks consist of so many fractures in this fault shear zone that with penetration of hydrothermal solution in fractures and fault system, without mineral veins and mineralized (Au, Ag, Cu, Pb, Zn and Para genes) veins are formed. Near of them different dykes penetrated in some fractures that altered the host rocks. General and detailed geological research (in 12 regions of this area) showed that this area contains of so much fracture and faults that formed relation of left lateral shear zone.Determinated of these small and huge fractures were classified them to D, P, X, T, R and R' fracture groups that each one have tectonic specifics. Another way research of dykes and fracture of them, showed tension regions that located in west and central of study area and agreement with T, R and D types of fracture. Notice to these fractures controlled mineralized veins, we studied all of fractures and the veins of them in 12 Mining areas that resulted mineralized veins located in R, R' and D types of fracture.

In soft soil surface layer the intensity of seismic waves are more and it causes more destruction. On the other hand in geophysical aspect, for estimation of softness or hardness of layers there is a suitable scale that named shear wave velocity.In this research, shear wave velocity in the first layer is calculated by 80 refraction seismic profiles in Bam. This area is zoned by shear wave velocity. Destroyed map of the 26th of Dec 2003 earthquake that has been immediately prepared. is compared with the shear wave velocity in the first layer and significant results achieved. as we know in low velocity zones destruction must be more and vice versa, but somewhere that is not happen, as we guess it is for kind of construction, distance to fault, depth of bed rock and etc.

According to importance of Tehran and its suburbs and by gathering information and researches done before, the fact is that in most of subjects there are a lot of questions without answers and there are some areas, specially in south of Tehran without any work done.This article shows up investigation on Parchin fault (Eivanaki) base on geomagnetic exploration method. The purpose of this research is to understand geophysical and tectonic conditions or in other fact, by using geomagnetic method, we found out if there could be any fault and by analyzing magnetic data done in the field, we will see that magnetic chart follow the field structure and there could be parchin fault.

Gravity anomalies always include the total effects (combination of the structures which have different densities and depths) of the study area and beyond.The regional-residual resolution of the potential field continues to be a topic of considerable interest among geophycists even to a present time. In spite of a large number of sophisticated analytical techniques both in the space and frequency domain, there are instances where interpreters are not satisfied with the regional and residual components obtained by this method.The finite element method (FEM), which has been used in potential field interpretation for decades, makes complex problems to be solved easily and accurately.A regional gravity anomaly, based on element shape functions used in finite element analysis, is developed. The first step of FEM is to identify the elements and then to decide onthe boundary of the solution space, the solution space is divided into elements. After determination of the geometrical structure of the solution space, the most suitable elements should be chosen for this geometrical structure. The agreement between the geometry and the elements is quite important for the convergence to the best possible solution.In this work FEM was applied to a theoretical model and to gravity data from salt dome structure in Qom to produce the regional and residual anomalies.