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SURFACE DISPLACEMENTS IN ACTIVE TECTONICS AREAS STUDIED BY PSI TECHNIQUES

SURFACE DISPLACEMENTS IN ACTIVE TECTONICS AREAS STUDIED BY PSI TECHNIQUES Salvatore Stramondo 1 , Can Zulfikar 2 , Mine Demircioglu 2 , Evangelos Lagios 3 ,Vassilios Sakkas 3 , Athanassios

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SURFACE DISPLACEMENTS IN ACTIVE TECTONICS AREAS STUDIED BY PSI TECHNIQUES

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  1. SURFACE DISPLACEMENTS IN ACTIVE TECTONICS AREAS STUDIED BY PSI TECHNIQUES Salvatore Stramondo1, Can Zulfikar2, Mine Demircioglu2, Evangelos Lagios3,Vassilios Sakkas3, Athanassios Ganas4, Kostantinos Stamatopoulos5, Michael Foumelis6, Issaak Parcharidis6, Fabrizio Novali7, Christian Bignami1, Marco Chini1 1Istituto Nazionale di Geofisica e Vulcanologia, National Earthquake Center, Via di Vigna Murata 605, Rome, Italy, Phone: +39 06 51860659, Email: salvatore.stramondo@ingv.it 2 Bogazici University, Kandilli Observatory and Earthquake Research Institute, Earthquake Engineering Department, 34684 Cengelkoy, Istanbul, Turkey 3 Remote Sensing Laboratory, Department of Geophysics & Geothermics, University of Athens, Panepistimiopolis –Ilissia, Athens 15784, Greece. 4 Institute of Geodynamics, National Observatory of Athens, Lofos Nymfon, Thission, 11810 Athens, Greece 5 Stamatopoulos & Associates Co. 6 Harokopio University of Athens, Dep. of Geography, El. Venizelou, 17671 Athens 7 Tele-Rilevamento Europa - T.R.E. srl

  2. Overview • - The Terrafirma Extension Tectonic Theme (TFX-TT) • The case studies: Istanbul, NAFS, Ionian Islands and Rio Antirio • SAR data and the PSI products used in the study • Comparison & integration and Value Added products • Conclusions

  3. The Terrafirma Extension Tectonic Theme (TFX-TT) • The activities and the results discussed in this talk have been developed in the framework of TERRAFIRMA Extension project in the Tectonic Theme. • - TERRAFIRMA is a pan-European ground motion information service based on satellite data and developed in support of policies aimed at protecting the citizen against natural and anthropogenic hazards.

  4. The Terrafirma Extension Tectonic Theme (TFX-TT) • Main Objectives: • providing services for seismic hazards • delivering services based on users needs

  5. The Terrafirma Extension Tectonic Theme (TFX-TT) • Two macro services are envisaged: • CRUSTAL BLOCK BOUNDARIES service • composed by sub-services: • Major and local fault investigation • Earthquake cycle investigation • Vertical deformation source in urban areas • SOIL VULNERABILITY MAPS service

  6. The Terrafirma Extension Tectonic Theme (TFX-TT)

  7. The case studies: Istanbul, NAFS, Ionian Islands and Rio Antirio • Istanbul's long history of earthquake damage relates to the North Anatolian Fault that passes only a few tens of kilometres away beneath the Sea of Marmara. • During the last 500 years, at least eight earthquakes with magnitudes greater than 7 have occurred close to Istanbul causing high casualties and great damage. • Following the magnitude 7.4 Izmit earthquake in 1999, considerable effort has been devoted to assessing risk in urban areas. Istanbul Metropolitan Municipality has taken the initiative with an extensive microzonation project that will eventually cover the entire metropolitan area.

  8. The case studies: Istanbul, NAFS, Ionian Islands and Rio Antirio • The North Anatolian Fault System (NAFS) is one of the most seismically active structures in the world. The NAFS is predominantly a single right-lateral strike-slip fault with a differential slip rate of 10-20 mm/yr. • The 1999 Izmit-Kocaeli(Mw7.4) and Düzce (Mw7.2) earthquakes occurred on the NAFS with the consequence of continental crust wedge (Anatolian Block) movement due to the squeeze between the Arabian and the Eurasian plates.

  9. The case studies: Istanbul and NAFS, Ionian Islands Rio Antirio • The central Ionian islands play an important role in the kinematic processes of the eastern Mediterranean, since it lies within a very active seismotectonically complex area that is undergoing rapid and intense ground deformation. • The highest seismic activity in Europe currently takes place in such region, constituting part of the Eastern Mediterranean lithosphere that is subducted beneath the Aegean lithosphere along the Hellenic Arc

  10. The case studies: Istanbul, NAFS, Ionian Islands and Rio Antirio • The Rio-Antirio bridge crosses the Corinth strait near the city of Patras, connecting Peloponnese with mainland Greece. The bridge is one of the most challenging engineering structures in Europe and the longest cable stayed bridge in the world with a continuous deck of 2,250 meters. • The bridge was under monitoring by the provider Harokopio University of Athens, in the frame of a previous project. • Near the bridge, and after its construction, a number of earthquakes occurred. Of special interest is the response of the foundation, that rests on very soft soil, on earthquakes that took place near it.

  11. The SAR data and the PSI products used in the study • The PSI coverage of the Metropolitan area of Istanbul has been obtained with 6 SAR frames. In particular the processing has been applied to two Envisat frames along Ascending orbit, two Envisat frames along the Descending one, and two ERS frames along Descending path. The overall number of SAR data is 180. • The ERS datasets span 1992-2000 while each Envisat analysis has covered 2003-2010. The spatial extension ranges 800-4000 km2 while the PS density is between 30 up to 220 PS/km2.

  12. The SAR data and the PSI products used in the study • PSI processing have yielded a subsidence map showing how spatially variable ground conditions are throughout urban Istanbul. Thirteen years' worth of observations not only show general trends that correlate well with the local geology, but also help to reveal other characteristics at smaller scale that would otherwise have gone undetected. • Average subsidence of 2-3 mm/year detected in the western part is probably due to consolidation and compaction triggered by extensive water pumping. This is a clear sign of unconsolidated soft sediments that can severely amplify seismic ground motion. • By contrast the eastern city, including the historic district, is built mostly on solid rock and is generally stable - though critical zones are revealed by the PSI study.

  13. The SAR data and the PSI products used in the study

  14. Comparison & integration and Value Added products Calculated grid 0.005 x 0.005 based building data distribution map

  15. Comparison & integration and Value Added products • Vs,30 distribution map In microzonation project area,Vs30 values for each 0.005 degree gridded cells have been obtained by averaging ground modeling and site response analysis of each 250m grid cells and they were attained to the 0.005 degree gridded cells

  16. Comparison & integration and Value Added products • The following figure shows the correlation of NEHRP (1997) site classes with PSI results for the data range from 1992 to 2000. • High subsidence regions are correlated with the Site Classes of D and E-F which are attributed to soft soil conditions.

  17. Comparison & integration and Value Added products Collapse, Very Heavy and Moderate damages observed in Istanbul City due to the 1999 Kocaeli Earthquake have been combined with the PSI results for the data range from 1992 to 2000.

  18. The SAR data and the PSI products used in the study • The PSI coverage of the NAFS area is the result 14 portions of frames acquired by ERS1-2 and Envisat satellites. • Envisat data are available either from ascending or from descending paths while ERS only from descending orbit. The overall number of SAR data is 137. • Temporal coverage: • - ERS dataset: 1992-1999, up to consider the last image just before the August 17th, 1999, Izmit earthquake; • - Envisat dataset: 2002-2009 • Spatial extension: 400-4000 km2 • PS density: 3-182 PS/km2

  19. The SAR data and the PSI products used in the study

  20. The SAR data and the PSI products used in the study Envisat ascending velocity map. The red stars are the epicentres of 1999 earthquakes. Green triangles indicate the reference points for each patch. Envisat descending velocity map. The red stars are the epicentres of 1999 earthquakes. Red triangles indicate the reference points for each patch. ERS velocity map. The red stars are the epicentres of 1999 earthquakes. Blue triangles indicate the reference points for each patch.

  21. Comparison & integration and Value Added products • The PSI maps have been integrated in a GIS platform with other data such as, geological map, seismic hazard map and a GPS regional network. • This GPS regional network has provided: • - the time series before the 1999 earthquakes occurred in the investigated area; • - the co-seismic vectors; • - the post-seismic time series up to 2009. • The average velocity from GPS solutions is relevant for PSI in order to provide anchor points to scale and fix the PSI velocities.

  22. Comparison & integration and Value Added products Pre-Izmit earthquake velocity field of the Marmara region. Map of GPS velocities relative to Eurasia and 95% confidence ellipses in the Marmara region for the pre-Izmit earthquake period (1988–1999) and location of the trans-NAF profile. Dashed lines show the width of the profile which includes the segment of the NAF that broke in the M = 7.4, 1999, Izmit, Turkey, earthquake (heavy, segmented line). Coseismic and postseismic (first 75 days) displacements (black arrows) of GPS sites relative to ANKR. Left figure shows map of Izmit region showing GPS sites and observed (including 95% confidence ellipses) and modeled (yellow arrows) horizontal co-seismic displacements relative to a station in Ankara. Right figure shows map of observed post-seismic GPS station displacements (black arrows) relative to ANKR during the first 75 days following the earthquake. Error ellipses indicate 95% confidence intervals. Profile-normal velocity components and 1 sigma uncertainties plotted versus distance along profile. Profile-parallel velocity components and 1 sigma uncertainties plotted versus distance along profile.

  23. Comparison & integration and Value Added products Eastern Marmara GPS monument locations (blue diamonds) and active faults shown in red.

  24. The SAR data and the PSI products used in the study (Ionian Islands) • ERS Descending • 1992 – 2000 • 39 Radar Images • ENVISAT Descending • 2003 – 2008 • 20 Radar Images

  25. The SAR data and the PSI products used in the study (Ionian Islands) ENVISAT Descending (2003 - 2010) 21 Scenes ERS Descending (1992 – 2000) 39 Scenes

  26. The SAR data and the PSI products used in the study (Rio Antirio) Advanced PSI analysis of ENVISAT ASAR data in descending and ascending orbits for the period 2002-2010. Effort to obtain a robust solution for both sides using a common reference point, to investigate differential motion of larger spatial scales.

  27. Comparison & integration and Value Added products (Rio Antirio) average 5x5 multi-look image (~10 m) DLR TerraSAR-X Strip-mode data of ~2 m spatial and 11-day temporal resolution ANTIRIO pylons Rio-Antirio cable bridge RIO

  28. Conclusions • TFX Tectonic Theme has developed and already delivered products based on PSI and in situ data • Data comparison and value adding activities have been performed by the local Research Institutions in Turkey and Greece • Value added maps for active faults (NAFS and Ionian Islands) and soil vulnerability (Istanbul and Rio Antirio) are the main outcomes. Such products are now available to the End Users Community (National Authorities and Civil Protections). • Next steps: SBAS processing for the Italian case study, i.e. the Messina Strait area, has been completed. Value adding activities will begin soon.

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