INTERNATIONAL SEISMOLOGICAL PROJECTS
The Lithuanian Geological Survey under the Ministry of Environment takes part in the international seismological projects. These projects provide opportunity to perform deep Earth studies at large scale. The information obtained during the studies might be used for seismological, engineering and other kind of applications.
Fig. 1. Locations of seismic stations during the international passive seismic experiment PASSEQ 2006 – 2008. 1 and 2 mark sites of permanent broad-band and short-period seismic stations, 3 and 4 mark sites of temporary broad-band and short-period seismic stations (Wilde-Piórko et al., 2008).
The Lithuanian Geological Survey during 2006-2008 took part in the international passive seismic experiment PASSEQ 2006 – 2008. The main aim of the project was to study the lithosphere-asthenosphere system around the Trans-European Suture Zone (TESZ). The Tornquist-Teisseyre Zone (TTZ) in the central part of the TESZ is well expressed tectonic boundary between the young Palaeozoic West Europe and the Precambrian East European Craton. The study of the deep structure of the zone is important for understanding the tectonic processes of the past in Europe.
There participated 17 institutions from 10 countries in the PASSEQ 2006-2008 project:
1. Institute of Geophysics, University of Warsaw, Warsaw, Poland;
2. Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, Germany;
3. Institute of Geophysics, Czech Academy of Sciences, Prague, Czech;
4. Institute of Geodesy and Geophysics, Vienna University of Technology, Vienna, Austria;
5. Lithuanian Geological Survey, Vilnius, Lithuania;
6. Institute of Geophysics, Polish Academy of Sciences, Warsaw, Poland;
7. University of Leicester, Leicester, UK;
8. Geological Survey of Denmark and Greenland, Copenhagen, Denmark;
9. GeoForschungsZentrum Potsdam, Potsdam, Germany;
10. Eötvös Loránd Geophysical Institute, Budapest, Hungary;
11. University of Oklahoma, Norman, USA;
12. Central Seismological Observatory, Erlangen, Germany;
13. Institute of Rock Structure and Mechanics, Czech Academy of Sciences, Prague, Czech;
14. University of Helsinki, Helsinki, Finland;
15. Sodankylä Geophysical Observatory, University of Oulu, Oulu, Finland;
16. University of Potsdam, Potsdam, Germany;
17. Vilnius University, Vilnius, Lithuania.
There were installed about 200 temporary seismic stations along the 1200 km long and 400 wide area from Germany throughout Check Republic and Poland to Lithuania (Fig. 1). The spacing between seismic stations in the central profile was 20 km, and in other places around 60 km. Totally there were installed 147 temporary triaxial short-period seismic stations and 49 temporary triaxial broad-band seismic stations which provided recording from June 2006 until July 2008. In the PASSEQ data base there were also included data of permanent seismic stations in the territory.
The temporary seismic stations have been installed in calm and remote sites: like forest huts, castles, monasteries, little farms, etc. Sampling frequency was 20 Hz, 50 Hz ir 100 Hz, and depending on it stations have been serviced every 1 – 5 months. The recorded data was converted into miniSEED format and stored and processed in GEOFON data base in Potsdam (Germany). During the period of the passive seismic experiment the seismic stations have registered earthquakes and other seismic events from all over the world. After the experiment, data was collected, processed and analyzed.
During the PASSEQ project there were installed 26 temporary seismic stations in the territory of Lithuania which recorded data from 9th of July 2006 until 10 th of January 2008. The data recorded by the seismic stations installed in the territory of Lithuania was used to study the seismicity in Lithuania and adjacent areas (Janutyte et al., 2012), to model Earth crust and the deep structure of the upper mantle using teleseismic tomography methods.
Fig. 2. Map of seismic stations installed in the territory of Lithuania during the PASSEQ 2006 – 2008 project. There were installed 26 temporary seismic stations in the territory of Lithuania.
More about PASSEQ 2006-2008 project and its results is here:
1. Wilde-Piórko, M., Geissler, W. H., Plomerová, J., Grad, M., Babuška, V., Brückl, E., Cyziene, J., Czuba, W., England, R., Gaczyński, E., Gazdova, R., Gregersen, S., Guterch, A., Hanka, W., Hegedűs, E., Heuer, B., Jedlička, P., Lazauskiene, J., Keller, G. R., Kind, R., Klinge, K., Kolinsky, P., Komminaho, K., Kozlovskaya, E., Krüger, F., Larsen, T., Majdański, M., Málek, J., Motuza, G., Novotný, O., Pietrasiak, R., Plenefisch, Th., Růžek, B., Sliaupa, S., Środa, P., Świeczak, M., Tiira, T., Voss, P., and Wiejacz, P. (2008), PASSEQ 2006-2008: Passive Seismic Experiment in Trans-European Suture Zone. Studia Geophysica et Geodaetica, vol. 52, issue 3, pp. 439-448
2. Janutyte, I., Kozlovskaya, E., Motuza, G., and PASSEQ Working Group (2012), Study of Local Seismic Events in Lithuania and Adjacent Areas Using Data from the PASSEQ Experiment. Pure and Applied Geophysics, DOI: 10.1007/s00024-012-0458-8
The EUROBRIDGE'95 is the deep seismic sounding project in the Baltic Sea, Lithuania, Belarus and Ukraine (Fig. 3). The EUROBRIDGE project aimed to study processes of collision and accretion of the paleocontinent (Fenoskandia, Volgo-Uralia and Sarmatia) 1,85-1,80 Ga ago, and to study deep structure of the East European Craton and the geological-tectonic complexes in the Baltic Shield and Ukraine Shield. The core of the EUROBRIDGE was 1500 km long wide angle reflection and refraction profile, which continued from the eastern coast of Sweden throughout the Baltic Sea, Lithuania and Belarus to Ukraine (Yliniemi et al., 2001).
The participant institutions in the EUROBRIDGE project:
1. Sodankylä Geophysical Observatory, University of Oulu, Oulu, Finland;
2. Institute of Seismology, University of Helsinkio, Helsinki, Finland;
3. Department of Geosciences, University of Oulu, Oulu, Finland;
4. GeoForschungsZentrum Potsdam, Potsdam, Germany;
5. Lithuanian Geological Survey, Vilnius, Lithuania;
6. Institute of Geophysics, University of Warsaw, Warsaw, Poland;
7. Institute of Geophysics, Polish Academy of Sciences, Warsaw, Poland;
8. Department of Earth Sciences, Uppsala University, Uppsala, Sweden;
9. Division of Earth Sciences, University of Glasgow, Glasgow, UK.
Fig. 3. The EUROBRIDGE profile. Green color covers areas of Phanerozoic sediments, yellow – of crystalline basement exposed on the surface (Bogdavona et al., 1996).
In 1994 the first part of the EUROBRIDGE profile was carried from Västervik (Sweden) to Šventoji (Lithuania). In 1995 the EUROBRIDGE'95 profile of 280 km length stretching NW-SE direction along the territory of Lithuania was carried out. During the project the TNT devices of 1 tone have heen blasted at the shot-points located every 30 km along the profile. And only in one shot-point near Gotland there was used TNT device of 3 tones. Altogether along the profile there were installed seismic stations for recording generated seismic waves. In 1997 the EUROBRIDGE profile was continued to the territory of Ukraine.
The data collected during the EUROBRIDGE project was analyzed and combined with the data of studies of magnetic, gravimetric, electrical conductivity and heat-flow. The results revealed the major tectonic structures and blocks in the region, and their age and processes which resulted the geological-tectonic structures (Bogdavona et al., 1996).
More about the EUROBRIDGE project and its results can be found here:
1. Bogdanova, S., and EUROBRIDGE colleagues (1996), EUROBRIDGE: Palaeoproterozoic Accretion of Sarmatia and Fennoscandia. In: D. G. Gee and H. J. Zeyen (eds.) „EUROPROBE 1996 – Lithosphere Dynamics: Origin and Evolution of Continents“, EUROPROBE Secretariat, Uppsala, 81-86
2. Yliniemi, J., Tiira, T., Luosto, U., Komminaho, K., Giese, R., Motuza, G., Nesedkin, V., Jacyna, J., Seckus, R., Grad, M., Czuba, W., Janik, T., Guterch, A., Lund, C.-E., and Doody, J. J (2001), EUROBRIDGE'95: Deep Seismic Profiling within the East European Craton. Tectonophysics, 339, 1-2
3. Giese, R., and EUROBRIDGE Working Group 1 (1999), Seismic velocity structure across the Fennoscandia-Sarmatia suture of the East European Craton beneath the EUROBRIDGE profile through Lithunania and Belarus. Tectonophysics, 314, 1-3
4. Giese, R., and EUROBRIDGE Seismic Working Group (1998), EUROBRIDGE'97: deep seismic sounding of the Ukrainian Shield. Geofizicheskiy Zhurnal, 20, 4
The POLONAISE (POlish Lithospheric ONsets - An International Seismic Experiment) project was an international deep seismic sounding experiment which aimed to study the Trans-European Suture Zone (TESZ) which separates the Precambrian East European Craton and the West European Platform which has formed during Caledonian and Variscan orogenies (Fig. 4). The POLONAISE seismic experiment was carries out in Poland, Germany and Lithuania in 1997. There were completed five wide angle reflection and refraction seismic profiles which continued around 2000 km in total. There were used 63 shot-points and about 600 seismic stations installed along the profiles at safe distances. During the experiments there was obtained large data set which was used for tomography inversion, ray-tracing and other research methods. The data also enabled to model the 3D structures of the underground.
The participants in the POLONAISE project:
1. Institute of Geophysics, Polish Academy of Sciences, Warsaw, Poland;
2. Institute of Geophysics, University of Warsaw, Warsaw, Poland;
3. GeoForschungsZentrum Potsdam, Potsdam, Germany;
4. Lithuanian Geological Survey, Vilnius, Lithuania;
5. Department of Geosciences, University of Oulu, Oulu, Finland;
6. Sodankylä Geophysical Observatory, University of Oulu, Oulu, Finland;
7. Geological Institute, University of Copenhagen, Copenhagen, Denmark;
8. Department of Geological Sciences, University of Texas, Texas, USA;
9. Department of Earth Sciences, Uppsala University, Uppsala, Sweden.
Fig. 4. The profiles of the deep seismic sounding project POLONAISE. The shot-points marked as red stars (map compilled by Institute of Seismology University of Helsinki).
More about the POLONAISE project and its results can be found here:
1. Guterch, A., Grad, M., Thybo, H., Keller G. R., and POLONAISE Working Group, (1999), POLONAISE'97 – an International Seismic Experiment Between Precambrian and Variccan Europe in Poland. Tectonophysics, vol. 314, issues 1-3, pp, 101-121
2. Jensen, S. L., Janik, T., and Thybo, H. (1999), Seismic structure of the Palaeozoic Platform along POLONAISE'97 profile P1 in northwestern Poland. Tectonophysics, vol. 314, No. 1, pp. 123-143
3. Sroda, P., Czuba, W., Grad, M., Guterch, A., Gaczynski, E., and POLONAISE Working Group (2002), Three-dimensional seismic modelling of crustal structure in the TESZ region based on POLONAISE'97 data. Tectonophysics, 360 (1-4), 169-185
4. Wilde-Piorko, M., Grad, M., and POLONAISE Working Group (1999), Regional and teleseismic events recorded across the TESZ during POLONAISE'97. Tectonophysics, 314, 161-174
Information prepared by Andrius Pačėsa