PSI analysis of ground deformations along the south-western coast of the Gulf of Gdansk (Poland)

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1 FRINGE 2009 WORKSHOP, Advances in the Science and Applications of SAR Interferometry 30 November 4 December 2009 ESA-ESRIN Frascati, Italy PSI analysis of ground deformations along the south-western coast of the Gulf of Gdansk (Poland) Magdalena Czarnogórska, Marek Graniczny, Szymon Uścinowicz - PGI Raffaele Nutricato, Saverio Triggiani, GAP slr Oscar Davide Nitti, Politecnico di Bari, Fabio Bovenga CNR-ISSIA and Janusz Wasowski CNR-IRPI

2 Aim: Verify the stability of the sea coast (flooding area) Background information: geology, seismicity, glacio-isostatics, precise levelling indicate it should be some deformation Method: PSI can provide further useful look to ground displacements in the area in the recent past.

3 Location of The Gulf of Gdansk The Gulf of Gdansk is located in the southern part of the Baltic Sea Puck Lagoon

4 Surface Geology of The Gulf of Gdansk Holocene deposits (sand, mud, locally gytia and peat) thickness is from 0 to m on the Vistula river delta relatively soft and weak consolidated sand Gulf of Gdansk mud Pleistocene deposits (till, sand, gravel and clay): thickness from a few up to 200 m relatively well consolidated till and sand PLEISTOCENE HOLOCENE Vistula Delta mud locally sand and peat PLEISTOCENE till and sand

5 Measured tectonic movements of Gulf of Gdansk Earthquake 2004 with the epicentre in the Eastern part of the Gulf of Gdansk, 5.3 in the Richter scale. (records from the Polish seismograph stations) Some evidences of the neotectonics are registered Earthquakes since begining of XX century after W. Fjeldskaar et al. 2000

6 Postglacial uplift and subsidance As the ice cover has decayed, the uplifting movement picks up. The subsidence relaxed at the earliest in the marginal part of the ice-sheet covered area, while the disequilibrium affects the central part of it for a long time to come. Total postglacial uplift and subsidence (National Atlas of Sweden 1994)

7 Vertical Earth surface movements in the Gulf of Gdansk; proxies and questions Results of repeated precise geodetic levelling According to Wyrzykowski (1985) the NW coast of the Gulf is stable or uplifting in a rate up to 0.5 mm/y, and the SE coast is subsiding in the rate of 2.5 mm/year. According to Kowalczyk (2006) the NW coast of the Gulf is subsiding in a rate about 0.5 mm/y, whereas the SE coast is subsiding in the rate up to 3.5 mm/year. Geodetic models based on repeated precise geodetic levelling show large scale subsiding on all or almost all coast of the Gulf of Gdansk.

8 Mareographic data ; Średnie roczne stany wody PUCKU w latach Puck 1.9 mm/y regional or local 525 sea level changes? stany wody (cm) stany wody (cm) y = x lata Rates of water level rise allong the Gulf of Gdansk coast differ up to 0.8 mm/y. Gdynia 2.2 mm/y Średnie roczne stany wody w GDYNI w latach y = x lata 1.9 mm/y Gdansk 2.2 mm/y Gulf of Gdansk 2.7 mm/y Are these smallest differences caused by the real neotectonic activity? stany wody (cm) stany wody (cm) Gdansk 2.7 mm/y Śrenie roczne stany wody w GDAŃSKU w latach y = x mm/y lata High rate of sea level rise in Gdansk is most probably caused by subsidence of Holocene deltaic sediments. Tolkmicko 2.0 mm/y Średnie roczne stany wody w TOLKMICKU w latach y = x lata

9 PS results on Gdansk by SPINUA algorithm The AOI covers an area of about 550 km2 Dataset: ERS-1/2 descending acquisitions, (Track, Frame) = (36, 2511) 41 images from [ ] Reference image: 22/05/1997

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11 Morainic upland Vistula Delta mm/yr

12 Geocoding quality can be appreciated along the coast line and where buildings draw particular paths.

13 1 2 Morainic upland 1. Gdansk suburb (living area) unknown reason for local subsiding on the area build by Pleistocene tills and sands 2. The airport (glacial till, sand and clay)

14 Vistula river Morainic upland old town Vistula Delta PS velocity rate (mm/yr) PS< -5-5<PS< -3-2<PS< 2 some buildings occur subsiding rate, while others are stable culture (antrophogenic) layer is 2-3 m thick and up to 1000 years old

15 PS velocity rate (mm/yr) PS< -5-5<PS< -3-2<PS< 2 PS high velocity rate is connected probably with infrastructure elements as spans of bridge

16 PS velocity rate (mm/yr) PS< -5-5<PS< -3-2<PS< 2 Probably instabilty of infrastructure elements

17 aeolian sand - dune bank O l d c a n a l o f V i s t u l a r i v e r deltaic mud and sand 2 1,5 1 0,5 0-0,5-1 -1,5-2 -2,5-3 17/05/95 17/09/95 17/01/96 PS-12708, Vel=-6 mm/y, Coh= /05/96 17/09/96 17/01/97 17/05/97 17/09/97 17/01/98 17/05/98 17/09/98 17/01/99 17/05/99 17/09/99 17/01/00 17/05/00 17/09/00 Vistula Delta Gdansk oil rafinery (35 years old) The example of subsiding thick layer of Holocene, deltaic deposits

18 2 1,5 1 0,5 0-0,5-1 -1,5-2 -2,5-3 PS-8748, Vel=-5 mm/y, Coh= /09/95 17/01/96 17/05/96 17/09/96 17/01/97 17/05/97 17/09/97 17/01/98 17/05/98 17/09/98 17/01/99 17/05/99 17/09/99 17/01/00 17/05/00 17/09/00 Vistula Delta aeolian sand - dune bank marine sand and gravel 17/05/95

19 According to map of areas affected by climate changes we expected higher deformation rate on deltaic deposits

20 Conclusions PSI results seem to confirm previous collected information on dynamics of Baltic coastal zone Selected sites of the Gulf of Gdansk displayed a various PS velocity rates Generally, higher PS velocity rate is registered in Deltaic sediments than in Morainic Upland layers. Oil rafinery targets, showed the highest displacements to 8 mm/yr. While Vistula outlet site showed less displacement rate about -4 mm/yr. The Old Town and the central part of Gdansk city are rather stable. Some instabilities were noticed in the vicinity of spans of bridges. But there is still unknown reason of some subsidence zones in Moranic Upland Some evidence of movements were registered trough PSI but it is not easy to separate it between antropogenic and natural causes Investigations of PS motions will be continued in the detailed scale, especially comparing GPS and hydrogeological data It also seems that PSI analysis should be tested on larger area

21 Thank you very much for your attention