We have obtained a solution for the velocity of westward drift from the induction equation in which an approach for main geomagnetic field was built. Distribution functions B(r, t) entered into the induction equation have been built by the observatories' data in North America and the Europe from 1991 to 2006. The longitudinal &#x2212;0.123 degree/year and latitudinal 0.068 degree/year drifts were defined in North America. And the longitudinal &#x2212;0.257 degree/year drift was defined in Europe from 1991 to 2006. These drifts are similar to results of other studies.

G. Bayanjargal

The Study of Westward Drift in the Main Geomagnetic Field

This paper presents use of semiempirical method for seismic hazard zonation. The seismotectonically important region of Uttarakhand Himalaya has been considered in this work. Ruptures along the lineaments in the area identified from tectonic map are modeled deterministically using semi empirical approach given by Midorikawa (1993). This approach makes use of attenuation relation of peak ground acceleration for simulating strong ground motion at any site. Strong motion data collected over a span of three years in this region have been used to develop attenuation relation of peak ground acceleration of limited magnitude and distance applicability. The developed attenuation relation is used in the semi empirical method to predict peak ground acceleration from the modeled rupture planes in the area. A set of values of peak ground acceleration from possible ruptures in the area at the point of investigation is further used to compute probability of exceedance of peak ground acceleration of values 100 and 200 gals. The prepared map shows that regions like Tehri, Chamoli, Almora, Srinagar, Devprayag, Bageshwar, and Pauri fall in a zone of 10&#x25; probability of exceedence of peak ground acceleration of value 200 gals.

Anand Joshi

Ashvini Kumar

Heriberta Castanos

Cinna Lomnitz

Seismic Hazard of the Uttarakhand Himalaya, India, from Deterministic Modeling of Possible Rupture Planes in the Area

3D realistic sea surface imaging from 3D dual-sensor towed streamer data is presented. The technique is based on separating data acquired by collocated dual-sensors into up-going and down-going wavefields. Subsequently, these wavefields are extrapolated upwards in order to image the sea surface. This approach has previously been demonstrated using 2D data examples. Here, the focus is on 3D data. Controlled 3D data based on the Kirchhoff-Helmholtz algorithm is generated, and the 3D sea surface imaging technique is applied. For coarsely spaced streamers from 3D field data, the technique is applied streamerwise (i.e., 2D wavefield separation, extrapolation, and imaging). In the latter case, the resulting sea surface profiles corresponding to each time frame are interpolated to demonstrate that the main sea surface characteristics are preserved, and artefacts due to 2D processing of 3D data are mainly limited to areas corresponding to large angles of incidence. Time-varying sea surfaces from two different 3D field data are imaged. The data examples were acquired under different weather conditions. The imaged sea surfaces show realistic wave heights, and their spectra suggest plausible speeds and directions.

Okwudili C. Orji

Walter S&#xf6;llner

Leiv-J. Gelius

Imaging 3D Sea Surfaces from 3D Dual-Sensor Towed Streamer Data

This study aims at evaluating the feasibility of an installation for space heating and cooling the building of the university in the center of the city Aachen, Germany, with a 2500&#x2009;m deep coaxial borehole heat exchanger (BHE). Direct heating the building in winter requires temperatures of 40&#xb0;C. In summer, cooling the university building uses a climatic control adsorption unit, which requires a temperature of minimum 55&#xb0;C. The drilled rocks of the 2500&#x2009;m deep borehole have extremely low permeabilities and porosities less than 1&#x25;. Their thermal conductivity varies between 2.2&#x2009;W/(m&#x000B7;K) and 8.9&#x2009;W/(m&#x000B7;K). The high values are related to the quartzite sandstones. The maximum temperature in the borehole is 85&#xb0;C at 2500&#x2009;m depth, which corresponds to a mean specific heat flow of 85&#x2009;mW/m2&#x2013;90&#x2009;mW/m2. Results indicate that for a short period, the borehole may deliver the required temperature. But after a 20-year period of operation, temperatures are too low to drive the adsorption unit for cooling. In winter, however, the borehole heat exchanger may still supply the building with sufficient heat, with temperatures varying between 25 and 55&#xb0;C and a circulation flow rate of 10&#x2009;m3/h at maximum.

Lydia Dijkshoorn

Simon Speer

Renate Pechnig

Measurements and Design Calculations for a Deep Coaxial Borehole Heat Exchanger in Aachen, Germany

Microgravity investigations are now recognized as a powerful tool for subsurface imaging and especially for the localization of underground karsts. However numerous natural (geological), technical, and environmental factors interfere with microgravity survey processing and interpretation. One of natural factors that causes the most disturbance in complex geological environments is the influence of regional trends. In the Dead Sea coastal areas the influence of regional trends can exceed residual gravity effects by some tenfold. Many widely applied methods are unable to remove regional trends with sufficient accuracy. We tested number of transformation methods (including computing gravity field derivatives, self-adjusting and adaptive filtering, Fourier series, wavelet, and other procedures) on a 3D model (complicated by randomly distributed noise), and field investigations were carried out in Ghor Al-Haditha (the eastern side of the Dead Sea in Jordan). We show that the most effective methods for regional trend removal (at least for the theoretical and field cases here) are the bilinear saddle and local polynomial regressions. Application of these methods made it possible to detect the anomalous gravity effect from buried targets in the theoretical model and to extract the local gravity anomaly at the Ghor Al-Haditha site. The local anomaly was utilized for 3D gravity modeling to construct a physical-geological model (PGM).

A. Al-Zoubi

L. Eppelbaum

A. Abueladas

M. Ezersky

E. Akkawi

Removing Regional Trends in Microgravity in Complex Environments: Testing on 3D Model and Field Investigations in the Eastern Dead Sea Coast (Jordan)

The formation of sinkholes along the Dead Sea is caused by the rapid decline of the Dead Sea level, as a possible result of human extensive activity. According to one of the geological models, the sinkholes in several sites are clustered along a narrow coastal strip developing along lineaments representing faults in NNW direction. In order to understand the relationship between a developing sinkhole and its tectonic environment, a high-resolution (HR) three-dimensional (3D) seismic reflection survey was carried out at the western shoreline of the Dead Sea. A recently developed 3D imaging approach was applied to this 3D dataset. Imaging of subsurface is performed by a spatial summation of seismic waves along time surfaces using recently proposed multipath summation with proper weights. The multipath summation is performed by stacking the target waves along all possible time surfaces having a common apex at the given point. This approach does not require any explicit information on parameters since the involved multipath summation is performed for all possible parameters values within a wide specified range. The results from processed 3D time volume show subhorizontal coherent reflectors at approximate depth of 50&#x2013;80&#x2009;m which incline on closer location to the exposed sinkhole and suggest a possible linkage between revealed fault and the sinkholes.

Shemer Keydar

Benjamin Medvedev

Abdallah Al-Zoubi

Michael Ezersky

Emad Akkawi

3D Imaging of Dead Sea Area Using Weighted Multipath Summation: A Case Study

In order to predict the fluid in thin layer precisely, this paper proposed a high-resolution method for fluid prediction. The method used geostatistical inversion with lithology masks to calculate water saturation. We applied this method to theoretical model and real data. The result was compared with that of prestack AVA simultaneous inversion for fluid prediction. It showed that this method had high resolution both in vertical and lateral directions for fluid prediction and could also predict the fluid in thin layer efficiently.

Zhen Yu

Jing He

A High Resolution Method for Fluid Prediction Based on Geostatistical Inversion

We present an experiment conducted in Kola Bay off the Barents Sea in which new, six-component electromagnetic seafloor receivers were tested. Signals from a powerful, remote super-long wave (SLW) transmitter at several frequencies on the order of tens Hz were recorded at the six sites along a profile across Kola Bay. In spite of the fact that, for technical reasons, not all the components were successfully recorded at every site, the quality of the experimental data was quite satisfactory. The experiment resulted in the successful simulation of an electromagnetic field by the integral equation method. An initial geoelectric model reflecting the main features of the regional geology produced field values that differed greatly from the experimental ones. However, step-by-step modification of the original model considerably improved the fit of the fields. Thereby specific features of the regional geology, in particular the fault tectonics, were able to be corrected. These preliminary results open the possibility of inverse problem solving with more reliable geological conclusions.

Valery Grigoryev

Sergey Korotaev

Mikhail Kruglyakov

Darya Orekhova

Yury Scshors

Evgeniy Tereshchenko

Pavel Tereshchenko

Igor Trofimov

Preliminary Results of Marine Electromagnetic Sounding with a Powerful, Remote Source in Kola Bay off the Barents Sea

Laurence Jouniaux

Tsuneo Ishido

Electrokinetics in Earth Sciences

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International Journal of Geophysics - Table of contents 2013

International Journal of Geophysics | Hindawi

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International Journal of Geophysics publishes research focused on all areas of theoretical, observational, applied and computational geophysics.

International Journal of Geophysics