BRASS: Bright Reflector Characterisation in a Geodynamically Active Region with Recurring Swarm Seismicity
Final Report Abstract
This study aimed to image and analyse the structures in the West Bohemia Seismic Zone in 3-dimensions. The main focus of the analysis was placed on seismic imaging using the 9HR-91 active seismic profile, due to its crooked line geometry near the main swarm area. Two advanced seismic imaging methods were used, Kirchhoff PreStack Depth Migration (KPSDM) and Coherency-Based Kirchhoff PreStack Depth Migration (CM). The CM produced low noise 3D images of the reflections from the near surface down to the base of the crust. In particular, the top of the highly reflective lower crust is imaged with great clarity. Other individual reflections can now be clearly seen. In the shallow crust, further analysis of the individual shots revealed previously unknown structures and their dips. The Bright Spot is now known to be made up of three individual reflectors, however further analysis of Bright Spot reflection A was inconclusive. Several the modelling parameters to be assumed, which probably played a role in the failed modelling. Further work needs to be done to confirm if this reflection is related to the Fichtelgebirge crystalline unit. Due to the highly linear nature of the MVE-90 profile, no 3D information could be obtained. Furthermore, the reflective structures imaged in the MVE-90 and 9HR-91 profiles could not be correlated, probably due to the presence of the Pocatky-Plesna Shear Zone between the two profiles. Further imaging between the two profiles is necessary to tie the reflections, which could be accomplished in the future using earthquake recordings at local seismic stations. This study also used earthquake waveforms recorded at station NKC to image the reflective structures in the middle and lower crust beneath the Cheb Basin. The resulting images from KPSDM correlate very well with the nearby 9HR-91 CM image. The results of this study are very promising and open the opportunity to use locally recorded earthquake data to investigate the crustal structures throughout West Bohemia / Vogtland.
Publications
- Characterization of Bright Reflectors Imaged in the West Bohemia Seismic Zone, 77. Jahrestagung der Deutschen Geophysikalischen Gesellschaft, 27-30 March 2017
Alexandrakis, C., Schreiter, L., Jusri, T., Buske, S.
- Die Triggerung der NW-Böhmischen Schwarmbeben: eine Diskussion zu den möglichen Ursachen, 78. Jahrestagung der Deutschen Geophysikalischen Gesellschaft, 27-30 March 2017
Heinicke, J., Alexandrakis, C., Buske, S.
- Seismic Imaging and Characterization of Bright Spots in the West Bohemia Seismic Zone (Germany and Czech Republic), American Geophysical Union Fall Meeting 2017, Abstract Number NS13A-0004, San Francisco, USA
Alexandrakis, C., Schreiter, L., Hlousek, F., Jusri, T., Buske, S.
- 2018. Can hydroseismicity explain recurring earthquake swarms in NW-Bohemia? Geophysical Journal International, 212, 211-228
Heinicke, J., Woith, H., Alexandrakis, C., Buske, S., Telesca, L.
(See online at https://doi.org/10.1093/gji/ggx412) - 2019. Alteration as possible cause for transition from brittle failure to aseismic slip: the case of the NW- Bohemia/ Vogtland earthquake swarm region. J. Geodynamics
Heinicke, J., Stephan, T., Alexandrakis, C., Gaupp, R., Buske, S.
(See online at https://doi.org/10.1016/j.jog.2019.01.010) - Structural Model of the Cheb Basin, West Bohemia/Vogtland (Czech Republic and Germany) using Advanced Seismic Imaging Techniques, American Geophysical Union Fall Meeting 2019, Abstract Number NS43D-0858, San Francisco, USA
Alexandrakis, C., Bräunig, L., Hlousek, F., Buske, S.
- Advanced seismic imaging and structural model of the Cheb Basin, West Bohemia/Vogtland (Germany and Czech Republic), 80. Jahrestagung der Deutschen Geophysikalischen Gesellschaft, 23-26 March 2020, Berlin
Alexandrakis, C., Bräunig, L., Hlousek, F., Höser, M., Buske, S.
