What is seismic survey

Seismic survey 2011


The four-week seismic survey of the deeper subsurface in the Erfurt area began on April 28, 2011. One of the aims of these investigations, funded by the Federal Ministry of Education and Research (BMBF), was the preparation of a research drilling planned on the site of the combined cycle plant of Stadtwerke Erfurt. With the help of reflection seismics, the various geological units and storage conditions were mapped down to a depth of over 2000 m.

The Institute for Geosciences (IGW) of the FSU Jena, in cooperation with the Thuringian State Office for Environment and Geology (TLUG), has commissioned Geophysik GGD mbH from Leipzig, in the area of ​​the cities of Erfurt and Sömmerda as well as the communities of Alperstedt, Elxleben, Gamstädt, Grabsleben, Großrudestedt, Günthersleben-Wechmar, Mönchenholzhausen, Nöda, Ohrdruf, Rietnordhausen, Seebergen, Udestedt, Walschleben and Wandersleben to carry out extensive and high-quality seismic measurements. The work took place along three profiles with a total length of approx. 76 km to the west and north of the city of Erfurt. A profile with a length of approx. 16 km crosses the northern area of ​​the city of Erfurt from southwest to northeast. The other two profiles with lengths of 40 km and 20 km are to the west and north of the city of Erfurt.

The work was carried out at a close measuring point distance, at which geophones were set up every 10 m to serve as receivers. At a distance of 30 m, hydraulic vibrator vehicles were used to set excitation points from which seismic signals were sent underground.

By using special vibrator vehicles in particularly environmentally friendly and controllable vibroseis technology, pressure waves were generated on the earth's surface. These lie in the audible frequency range of 10-80 Hz and were reflected at the interfaces of the various rock formations located in the deeper subsurface and recorded by the geophones on the earth's surface. The registration, amplification and evaluation of the reflected waves took place in the central registration vehicle. With the help of special computer-aided analysis and filter programs, the incoming weak signals from the geophones were amplified many times over and overlying interference waves were eliminated. At the end of the elaborate evaluation on the computer, images were generated on which the storage conditions and the structure of the rock formations in the deeper subsurface can be recognized. The results of the seismic reflection measurements are published in scientific journals as part of the INFLUINS project.

Fig. 1: With the help of a vibrator vehicle, seismic waves are artificially generated in a frequency range from 10 to 80 Hz.

Fig. 2: In the central registration vehicle, all reflected seismic waves recorded by the geophones are registered, amplified and evaluated.

Fig. 3: The rock formations located in the deeper subsurface reflect the seismic waves in different ways and thus enable conclusions to be drawn about the storage conditions and structure of the rocks in the depths.