Geo- Electric & Electromagnetic
Investigations

by I. ÇAGLAR

Department of Geophysical Engineering,
Istanbul Technical University

Research Projects:

Study Area and Lines

Geothermal Exploration in Biga Peninsula, Northwestern Turkey, Using Geoelectrical methods Turkey is loacted within an important geothermal area, and has an estimated 31,500 MW geothermal heat potential (Mertoglu et al., 1995). Many hot spings with high temperature (up to 150 degrees) are located in Turkey (MORE DETAILS-1 and MORE DETAILS-2). Temperature in the geothermal systems strongly influences the geo-electrical resistivity of the geological materials. The main purpose of the research was to identify a potentially valuable new region in the Kestanbol Area using geo-resistivity and Self-Potential methods. Both methods are carried out along ten profiles with north-south direction. A main fractured zone that allows fluid circulation was found from the 3-dimensional inversion of the Self-Potential anomaly map. Two-dimensional geoelectric model indicates a good conductive region (<10 ohm-m)in the southwest part of Kestanbol.

Topographic Image

A re-interpretation of geological structure associated with Büyük Menderes Graben using geo-resistivity data Büyük Menderes Graben is the one of the major tectonic features of Aegean Region. Topographic picture images two major fault zones at the northern and the southern margines of the graben. The primary objective of this research is to understand the geoelectrical structure of the B. Menderes Graben that is shaped by several minor buried and major tectonic faults. The Schlumberger geo-resistivity data previously taken at about 300 sounding sites by Turkish Water Reseach Company (DSI) are re-interpreted to determine geoelectric structure of the Graben. The resistivity maps constructed for various depth (e.g. r=AB/2=10 m. and r=AB/2=60 m. suggest more resistive zones in the eastern part of the B. Menderes basin. Based on the two-dimensional geoelectric models Quaternary units are thinner around the onshore basin but thickened (up to 150-200 m) eastward, towards Aydin-Ortaklar.

Western Turkey

Research on Geoelectric Structure of the Gökova Graben, Aegean Region The Menderes massif with its northeasterly oriented elliptical shape has a significant imprint on the geological evolution of western Anatolia. In this region, we attempted to care to the Gökova graben in southwestern Anatolia, since it is not clearly known that whether this region has a graben construction. Our main goal in this study is to obtain the geoelectrical structure of the inland area of the Gökova rift and to illustrate the possible faults that control the construction of Gökova Graben, using the geoelectrical resistivity method. The 3-dimensional resistivity picture and the two-dimensional geoelectric models indicate that the tectonic structure is comparatively complex, and that the structural pattern is distrupted by numerous fault zones. Interpretation of geoelectrical structure pointed to that the inland area of the Gökova rift has an asymmetric graben structure as observed in both the Gediz and Büyük Menderes grabens.

Sun-Earth-Magnetosphere

Monitoring of telluric currents originated by atmospheric events The solar activity and magnetic storms caused by anormal variations of the micropulsations generally affect telephone satellite and radio communications(Table). Telluric currents have a number of origins caused by naturel events such as electrochemistry activities, atmospheric electricity, ionospheric conditions, solar activity and geomagnetism. Between 21 and 27 August 1991 ground based observations of the telluric currents were made at Boyali (NW Turkey). The telluric (originated by Pc geomagnetic pulsations) and other currents (probable noises) are simultaneously recorded on a paper (example). The high frequency signals caused by possible atmospheric events are recorded as noises on magnetotelluric data during field studies at Tarakli site. In the future, similar observations can be planned.

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Constructed by I. Çaglar

Feb 2001