A continuous GNSS Monitoring Array in western Crete and the Permanent Calibration/Validation Facility for Satellite Radar Altimeters in Gavdos

摘要

The Aegean and its surrounding area is one of the most active seismic regions in the Mediterranean and West Eurasia. The island of Crete in particular lies on the collision zone between the Eurasian and the African lithospheric plates and undergoes large and fast geodynamic deformations at a velocity of about 36mm/yr. Nonetheless, the level of our knowledge about the geological structure and the tectonic deformation of this Hellenic subduction zone is limited primarily because continuous as well as long-term geodetic measurements of high quality are not readily available. The Technical University of Crete has been operating a permanent GPS station, called TUC1, in the area since 1997. A second station, TUC2, was installed in the University campus and next to previous site in 2003. This has been part of EUREF permanent network as of 2004, and that station is collocated with a satellite laser ranging station. Another two permanent GPS sites, named GVD0 and GVD6, were installed in 2004 and 2007 respectively, on the island of Gavdos, located about 80 km south of Crete. The GVD0 is collocated with a DORIS satellite beacon (named GAVB) while GVD6 is tied to a tide gauge. In addition to the above infrastructure, two more continuous operating GNSS sites are ready to be installed in the west Crete. These new stations will be collocated with tide gauges and seismographs and their data will be transmitted to a Control Operations Center via satellite communication links. All these continuous GNSS sites have been providing a wealth of precise geodetic data useful not only for deformation and geodynamic applications but also for a number of other research applications, such as the support and operation of the Gavdos permanent facility for the calibration/validation of satellite radar altimeters and for monitoring sea level changes, the development of statistical quality control algorithms, the monitoring of "silent and slow earthquakes", etc. We present the main components of the continuous GNSS arrays in west Crete, the Gavdos permanent satellite calibration facility and our future plans for extending our monitoring array over other parts of Crete.