SPARKER IN LAKES; REFLECTION DATA FROM LAKE IZNIK

Sparker in lakes; reflection data from Lake Iznik

Bedri Alpar, Kurultay Öztürk, Fatih Adatepe, Sinan Demirel, Nuray Balkis

Istanbul University, Institute of Marine Sciences and Management, Vefa, 34116 Istanbul, TURKEY

Abstract

The success of a sparker, a marine seismic energy source, would mainly depend on the physical characteristics of the water. In fresh or quasi­ fresh lakes, some extra technologies are needed. For the basic and fresh waters of Lake Iznik, we have designed and tried a special sparker container and also some new electrode array configurations. The results and some technical problems encountered will be discussed. Single electrode transducer case, which means that the energy discharging through i t will be many times higher if compared to the multi-electrode case, was found to be most practical for this particular expedition. It was in fact rather successful even the vertical resolution decreased about 2.5-3 times. Obtained shallow seismic profiles are used to image the stratigraphic and tectonic setting in the lake. Two unconformable main seismic units, which are separated by a major eroded surface 30-35 m below water surface, could be detected in the sub-surface fluviolacustrine sediments.

Keywords: Lake Iznik, sparker, seismic, lakes, geology