Geophysical Studies at El'gygytgyn Crater Lake
Lake El'gygytgyn, located in central Chukotka, NE Siberia, fills a basin 12 km in diameter and 170 m deep. The basin today is asymetrically located in the central and southeastern part of an impact crater of about 18 km in diameter. The lake is expected to have never been glaciated after its formation by an impact 3.6 Ma ago. This makes it a unique archive for paleoclimatic studies in arctic regions. Below is an aerial view on Lake El'gygytgyn. Ongoing multidisciplinary studies are carried out in order to study the generation, geometry, and thickness of the sediment fill and to provide a pre-site survey for a future deep drilling site. In particular, seismic, magnetic, hydrological, meteorological, geomorphological, sedimentological, and permafrost related studies provide information on (palaeo-)sedimentation processes.
Geophysical Survey at El'gygytgyn Crater Lake
Geophysical profiling of remote arctic lakes like the El´gygytgyn site in Northeast Siberia demands equipment, which is portable for men and operable to helicopter transport. The institute has developed a multi-modular aluminium platform for this, named "HELGA", that includes several profiling techniques. At Lake El´gygytgyn HELGA was used for seismic, geomagnetic, and bathymetric surveys.
For high resolution data acquisition a 3.5 kHz sediment-echosounder was used. The trigger interval was set to 1 second. An airgun system was applied for deeper penetration. The GI gun that was used as acoustic energy source had a 26 inch³ volume. Air pressure (110 - 130 bar) was supplied by two diving compressors (280 l/min) and 6 x 33 l air bottles. Shooting intervals were 10 and 14 seconds. A flexible multi-channel streamer collected the seismic returns and signals were stored along with navigation and trigger data on a 16-channel DAT recorder.
Multi-modular aluminium platform HELGA
Magnetic profile of Lake El'gygytgyn
Bathymetric profile of Lake El'gygytgyn
