Geodynamic Pattern of the West Bohemia during the October 2008 Earthquake Swarm

Transcription

1 10th Czech-Polish Workshop on RECENT GEODYNAMICS OF THE SUDETEN AND ADJACENT AREAS Szklarska Poręba, November 5-7, 2009 Geodynamic Pattern of the West Bohemia during the October 2008 Earthquake Swarm Vladimír Schenk, Zdenka Schenková and Richard Pichl Institute Rock Structure and Mechanics v.v.i. Academy of Sciences, Czech Republic, Praha

2 Motto : Role of geodesy, seismology and other geoscientific branches in geodynamic studies

3 Outlines 1. Historical steps in investigations of geodynamic studies 2. Geodetic data can stimulate new advanced, more complex understanding of geodynamic interpretations 3. Case example: the 2008 earthquake swarm, West Bohemia 4.. additional geo-scientific data improve and/or verify geodynamic interpretations 5. Conclusions and Outlooks

4 Historical steps in investigations of geodynamic studies End of the 19th Century earthquake recordings started, geodetic survey was already developed the 20th Century 1906 San Francisco earthquake geodetic survey after shock allowed rupture processes to be determined >>> Reid theory till 30ties - seismological investigations realized under the US Geodetic in 80 Coast Survey 90ties - the US Congress permitted that the GPS system can be used 80-90ties by civilians for geodetic and geodynamic studies the 21st Century May 2, 2000 President Clinton announces that accurate GPS access will no longer be restricted to the military, i.e. selective availability" was discontinued to receive a non-degraded signal

5 West Bohemia earthquake swarm area CERN GPS observations permanent sites active prepared epoch sites LUBY VACK s s s w w w a a a r r r m m m a a a r r r e e e a a a NOKO MARJ active prepared gravity observatory KOPA KVEC KRAJ HABA POUS SKAL SKA1 KYNS

6 GPS results and Interpretations obtained before 2008 earthquake swarm Horizontal and vertical movements determined for six permanent GPS stations situated in the area: KYNS, LUBY, MARJ, POUS, VACO and WTZR Schenk, Schenková a Jechumtálová, 2009, Stud. Geophys. Geod., 53, 3,

7 Horizontal site movements were analyzed with respect to main tectonic directions of the area, to the Mariánské Lázně tectonic zone and to Krušné hory fault system. Their movement components were evaluated along and across these zones. Correlation of the movements on all six sites confirm dextral movements along the Mariánské Lázně system. Compressions in the southern part of the West bohemia region and extensions in its northern part were confirmed too. Extension trends in the Cheb basin were detected already earlier by other authors. Schenk, Schenková a Jechumtálová, 2009, Stud. Geophys. Geod., 53, 3,

8 Recent stress field model Schenk, Schenková and Jechumtálová, 2009, Stud. Geophys. Geod., 53, 3,

9 West Bohemia earthquake swarm area Kraslice Luby NK K Horka dam Cheb basin NK K Cheb basin

10 !!! New Geodetic Stimulus!!! for geodynamic study 2008 earthquake swarm 2008 earthquake swarm

11 GPS Site Movements horizontal mm 0 vertical cm

12 km km km km km km km km depth interval km km km km km km km km km 28 Oct 2008 M L ~ km km km km

13 depth interval ~ 5-6 km NOKO NOKO depth interval km KOPA KOPA depth interval km

14 ?? Surface Deformations??

15 ?? Surface Deformations

16 Residu idual Gravity Data and Daily Earthquake Energy Relief cumulative energy magnitude of events KVEC KRAJ

17 Continuous GPS Monitoring of Surface Deformation POUS LUBY KYNS MARJ extension compression deformation [nstrain]? e a r t h q u a k e s w a r m.....

18 Conclusions and Outlooks 1. Recent geodetic measurements are already able not only to contribute geodynamic studies but also stimulate more complex understanding of geodynamic processes 2. Permanent GPS observations allow continuous surface deformations to be monitored and, in this way, a possible existence of geodynamic processes in the region to be identified 3. It is reasonable, and sometimes necessary, to combine permanent and campaign GPS measurements to investigate surface deformations in details details, e.g. in post-seismic period, etc.

19 10th Czech-Polish Workshop on RECENT GEODYNAMICS OF THE SUDETEN AND ADJACENT AREAS Sklarska Poreba, November 5-5, 2009 THE END Thank you for your attention

20 NOKO Nový Kostel přehrada Horka Kopanina KOPA