Geoscience Reference
In-Depth Information
Shallow water areas of nearshore zone were studied by side-scan sonar profiling
(CM2, C-MAX Ltd, UK) with search swath 100 m using a working acoustic fre-
quency of 324 kHz. Altogether, 1,500 km of side-scan profiling perpendicular to
the shoreline was done in 2005-2009 in the eastern Gulf of Finland. The distance
between profiles (186 m) permitted to receive continuous acoustic images of the
investigated sea bottom area as a whole, which were the basis to study the details of
surface sediment-type distribution. Side-scan profiling was accompanied by echo-
sounding. Repeated surveys of some nearshore zone areas and key profiles allowed
exploring the development of the bottom relief and sediment dynamics through time.
In the Kaliningrad area, side-scan sonar profiling was carried out along the seaward
side of the Curonian and Vistula (Baltiyskaya) spits, in some areas of the Curonian
and Vistula Lagoons, around the Sambian Peninsula, and along the underwater
pipeline from the D6 offshore oil field (“Kravtsovskoe”). Approximately 300 km
of side-scan lines were measured.
The interpretation of sonar data within both areas (the eastern Gulf of Finland
and Kaliningrad area) was confirmed by sediment sampling and underwater video
observations using the video-ROV Fish106M (Intershelf, St. Petersburg, Russia).
Sediment sampling (230 samples in the eastern Gulf of Finland and 300 samples in
the Kaliningrad area) along the side-scan sonar profiles used grab sampler and small
drag sampler. The sediment sampling within the coastal slope between the coastline
and the water depth of about 2.5 m was fulfilled by divers.
16.3 Results
The mapping of potential hazardous areas is one of the first steps toward hazard
and risk prediction. Therefore, the geological mapping of the sea bottom and the
coastal areas is the basis for the prognosis of hazards in coastal areas. There are
two different approaches for mapping of geological hazards: one suggests the map-
ping of the actual distribution of areas affected by hazardous processes, whereas the
other includes the mapping of potentially dangerous areas (the so-called method
of geodynamic potential which considers the probability of the process occur-
study, maps of geological hazard potentials for the eastern Gulf of Finland and the
16.4 Kaliningrad Area
16.4.1 Endogenic Processes
The Baltic Sea region is traditionally characterized as an area of very low seis-
mic activity. According to the General Seismic Zone Map of Russia, the maximal
