Journal of the Earth and Space Physics
Year:2001 | Volume:27 | Issue:1|Papers Count:9

To interpret the gravity anomaly of a Koromite mine in south - west of Iran, we have used the three dimensional inversion problems. The method introduced by Last and Kubik (1983) and improved by Lewi (1997) for high precision gravity data has been tested to determine the 3-dimensional form of the anomaly. The results of the inversion process have been approved by exploration drill holes in the area recently.

This paper describes a methodology for the integrated interpretation of airborne magnetic and airborne γ-ray spectrometer data. The Darrehzar porphyry copper deposit is situated in the Urumieh-Dokhtar magmatic assemblage of Central Iran. Phyllic and propylitic alteration are pervasive in the area but potassic and argillic alterations are not readily recognized on the surface. The spatial distributions of geophysical data resemble the lithological and alteration patterns in the area. The Darrehzar porphyry copper deposit is considered as a control site for determination of the degree that the geophysical data is correlated with the mineralization zone. Airborne magnetic/radiometric, geochemical lalteration and ground geophysical data sets have been integrated and analyzed using canonical correlation method. This technique is found to be useful for the delineation of hydrothermally altered areas and data compression.

In the last two decades, stochastic modeling and simulation of earthquake ground motions have been used for dynamic design of the structures. The most currently applicable method is ARMA processes. The advantage of this method is in nonlinear response of the structure and the relation of the physical parameters to the modeling parameters. Ten stations with three components were considered for this research to simulate strong motion accelerograms from the Manjil earthquake in 1999. The accelerograms which were generated from a given set of physical parameters were compared with the original set of the recorded one. The similarities between these two-time and frequency domain shows the effectiveness of the model. The accelerograms which are needed for dynamic design of the structure can be generated by knowing the probable fault distance and soil type.

In this study, turbulent flow around a Guassian hill in a water tunnel is studied. Using a hot film anemometer, velocity and turbulent qualities (such as turbulence flux and intensity) is measured at different parts of the model. To understand these measurements, mean velocity deviation and perturbation velocity fluctuation contours, also turbulence flux and intensity profiles are presented and the results are consistent with those obtained by other investigators. Also the cavities in the downwind of the hill cause intense turbulence its scale being in order of cavities. The increase of velocity around the hill especially above the crest is significant. These studies in the use of optimum wind energy in hilly regions are useful.

Cimmerian plate comprising of Anatolides, Taurides, Alborz, Central Iran, East Iran Belt (EIB), Central Afghanistan, South Pamir, Pontides and Lesser Caucasus blocks, are tectogenetically associated with wrenching, detachment faults and Riedel shears. Among the blocks those affected by wrench tectonics, detachment faults and Riedel shears are seismically very active. In addition, the Central Iran Block and East Iran Belt are attributed to ductile shear zones those behave as counter - flow boundaries of pseudoplastic power law fluids responsible for all seismic activities. East Iran Belt played the most important role of counter-flow boundaries for pseudoplastic power law fluids during intra - plate convergence and cal alkaline granitoid plutonic phases in the Central Afghanistan back arc basin block. Two major detachment fault zones viz., Makran Detachment Fault Zone (MDFZ) and South Iran Detachment Fault Zone (SIDFZ) have been inferred. MDFZ seems to be less active while SIDFZ is more active. The on-going activity of SIDFZ is envisaged by the deformation of Neogene sediments and by the occurrence of extensive salt beds those act as the lubricating agent for decollement. The detachment fault activities all along the intra-arc basin, arc proper and fore-arc basin zones of Zagros Orogen are also responsible for wrenching and Riedel shears (conjugate fracture). The northeast - southwest trending shears are inferred to be seismic prone. The wrenching is dominantly right-lateral strike slip with thrust.

A computer program was developed to predict the dispersion of gaseous pollutant in the atmosphere. This program relies on puff method, and in order to consider the wind shear effects, the program has the ability to consider the complete dynamic and unsteady atmospheric conditions. Plume rise of hot pollutants due to buoyancy effects was also considered. The program has the ability to perform the real-time calculations and uses on-line data of atmospheric conditions that are measured directly. In order to consider the effects of the presence of buildings and other obstacles or sudden changes in surface roughness by the dispersion of released materials, a model was added to evaluate the dispersion coefficients in the wake of obstacles. Using this relatively complete simulation, we analyzed the effects of the above parameters on the dispersion of gaseous pollutants in the atmosphere.

We analyzed the International Seismological Center (ISC) catalogue of seismological publications from 1980 to 1995 to investigate to what extent the information provided by an earthquake has been utilized to obtain a better understanding of earthquakes and seismic disaster. We select the ISC bulletin which has a wider coverage of seismological journals and languages than the Scientific Citation Index (SCI), so that there is less regional or language bias in the analysis. The earthquakes in the catalogue spans the period from 1975 to 1990. Papers which have direct relations with an earthquake as defined by the ISC catalogue ranges from 1 to 102 in order of magnitudes. The logarithm of the maximum number of papers on an earthquake is shown to be proportional to the magnitude of the) earthquake, which provides a possibility to define a 'normalized impact factor' of an earthquake, so that earthquakes with different magnitudes can be compared with each other. The magnitude span of earthquakes with a certain 'impact factor' and the 'impact factor' itself can be used in the regional comparisons. The analysis shows a regional difference that the academic impact strength" of the earthquakes occurring in Asian developing countries are not comparable to the societal effects of these earthquakes, implying that one of the future directions of the development of Asian seismology is to have more observations and more researches on the earthquakes occurred "at home.

One of the most important steps in the processing of VSP data is the separation of upcoming and down going waves. It can be performed by applying a velocity filter either in the f-k or t-p domain. In the f-k domain, upcoming and down going waves will be separated into two groups having negative and positive wave numbers, respectively. A simple way of extracting them is to remove energies with the positive or negative velocities in the f-k plane. Similarly, by transforming VSP data from t-x domain to t-p domain, upcoming and down going wave fields become separable and they are mapped to different quadrants of a t-p plane. This allows either upcoming or down going waves to be reconstructed by the application of inverse Radon transform to the related quadrant of the t-p plane. Results obtained by the t-p method are similar to those obtained by the f-k velocity filtering. However, by implementing an amplitude ratio-resting filter in the forward slant stack, the quality of the reconstructed wave field would be improved. The filter was based on the amplitude of a slant-stacked event. The event with different amplitudes can be identified and suppressed when amplitudes are incoherent. In this regared, the efficiency of the f-k filter and the Radon transform over synthetic and real VSP data are considered. For the real data, we compared the results of our written softwares with those of the ProMAX software.