Crustal Block Boundaries, North Anatolian Fault (NAF) Site
Zulfikar, Can1; Ozener, Haluk1; Stramondo, Salvatore2
1Bogazici University, KOERI, TURKEY; 2INGV, ITALY

A comprehensive analysis of the earthquake cycle is a key issue for the definition of the hazard in seismic areas. The analysis of active tectonic topics is oriented towards the investigation of three seismic phases: pre-, co- and post-earthquake. Although the effects of the co-seismic phase are now widely known and modelled accordingly by conventional Differential SAR Interferometry, there are major issues with regards to the remaining phases. Thus, the utility of this service for the end users is mostly related to the PSI technique, which is the tool that is best able to answer the remaining issues, and which allows the information gap on the interseismic phase, i.e. pre- and post- seismic phases to be filled. In particular, the post-seismic phase can be monitored to measure the amount and the surface extension of possible deformation rebound or residual strain release. This is a relevant issue for end users to estimate seismic hazard effectively. On the other hand the preseismic, or a-seismic, deformation remains an open issue, in particular for its modeling complexities. From West of 31.5°E toward the Marmara Sea region (Mudurnu/Akyaz��) the North Anatolian Fault System (NAFS) begins to lose its single fault line character and splays into a complex fault system. Data obtained during the recent high-resolution bathymetric survey of the Ifremer indicates that a single, thoroughgoing strike-slip fault system (Main Marmara Fault), cuts the Marmara Sea from east to west joining the 17.8.1999 Izmit earthquake fault with the 9.8.1912 Sarkoy- Murefte earthquake fault. The main Marmara Fault is argued to be a very young structure (about 200,000 years old), cutting across the older structures that formed the present NNESSW extensional pull-apart morphology of the Marmara Sea. Between 28.8E and 27.4E the Main Marmara Fault exhibits typical characteristics of a major strike slip fault. The fault follows the northern boundary of the Cinarcik Basin between Yesilkoy and the entrance of the Gulf of Izmit.
The service is aimed at providing value-added maps to investigate surface movements and to discriminate different crustal blocks based on the interpretation of PSI measurements and in situ data. The service is based on the H-1 PSI products plus the comparison with other external data sources able to provide an added value to the output products. Three subservices have been identified such as a) major and local fault investigation, b) earthquake cycle investigation and c) vertical deformation sources in urban areas. Coseismic interferograms obtained from standard InSAR can also be provided. They show the surface effects of earthquakes along the epicentral region and provide suitable information about the fault geometry.
PSI analysis has been aimed to investigate the interseismic and postseismic movements and make concerns about the possible explanation for detected signals. Finally, PSI maps will be compared with in situ surveys and ground measurements to achieve an added value product.
The input layers are listed as below:

  • full resolution PSI products;
  • Coseismic interferograms from standard InSAR;
  • GPS measurements: Up, East, North vectors;
  • optical levelling: vertical displacements at each benchmark and associate errors;
  • geological mapping;
  • geothecnical investigation;
  • seismological scenarios.