This study analyzed crustal deformation in the seismically active Patras Gulf region of Greece using GPS data. The GPS network was established in 1994 and expanded through additional campaigns in 1996, 2006, and 2011. The data show the Patras Gulf is opening up at a rate of 8-13 mm/yr with uplift of 5 mm/yr in the south. A continuous GPS station revealed southeast horizontal motion of 17.4 mm/yr and a clear signal from the 2008 Mw 6.4 Andravida earthquake. The results indicate increasing extension across the gulf and smaller extension near the Rio-Antirrio bridge area.

1. NATIONAL AND KAPODISTRIAN UNIVERSITY OF ATHENS FACULTY OF GEOLOGY & GEOENVIRONMENT DEPARTMENT OF GEOPHYSICS & GEOTHERMICS Laboratory of Remote Sensing CRUSTAL DEFORMATION STUDIES IN THE SEISMICALLY ACTIVE AREA OF PATRAS GULF (GREECE) Konstantina Vlachou, Vassilis Sakkas, Panagiotis Papadimitriou & Evangelos Lagios

2. Aims of the Study Study the Regional and Local Ground Deformation Integrate DGPS & Seismological data to identify ground motion due to seismic activity and active tectonism Model major fault movements Peloponnesus

3. Geodynamic Settings Seismotectonic map of Greece

4. Main Geological Units

5. Seismic Activity 1980 - 2011 M>3.6 Mw=6.4 Mw=6.4 Mw=5.6 Mw=5.4 CTF Patras Gulf

6. The Patras Gulf GPS Network 10 Bench marks 1 Continuous GPS station (RLSO) – Established 2006 Campaigns 1994 1996 2006 2011

7. Rio – Antirrio Bridge GPS network 7 Bench Marks 2008, 2009, 2011

8. DGPS Results 1994 – 2006 (ITRF 2000) Vertical Displacement

9. DGPS Results 1994 – 2006 Reference : No 50 Vertical Displacement 50

10. Strain Rate Field Blue arrows: Extension Red arrows: Compression

11. Rio – Antirrio Bridge GPS net

12. Continuous GPS station RLSO Station Velocit y ( ETRF ) Epoch 2005.00 CGPS Station V East (m m /yr) V North (m m /yr) V Up (m m /yr) RLSO -17.4 -15.2 +6.0 UoA1 -16.2 -22.4 +1.1 VLSM -6.4 -7.9 +0.5

13. (Mw=6.4, June 8 th 2008) Andravida Earthquake

14. Mw=6.4 Time Series of RLSO station 2006 – present (ITRF 2000) Mw=6.4

15. Conclusions Opening up of the Patras Gulf at a rate of 8 – 13 mm/yr Uplift of the southern Part of ≈ 5 mm/yr Westward increasing extension of the Patras Gulf Smaller extension in the Rio – Antirrio Area ≈ 7 mm/yr RLSO CGPS station revealed SE horizontal motion with respect to ITRF2000 The 2008 Andravida Earthquake (Mw=6.4) was clearly depicted in RLSO CGPS station, with a northward offset of about 10 mm

16. “ Google Earth” used to produce some of the Maps “ Generic Mapping Tool” (GMT ) was used for all the figures “ Grid_Strain” s/w of “Pesci A., Teza G., 2007” used for the strain calculation Acknowledgements Thank you for your Attention !