Klokotos GNSS InstallationKlokotos Thessaly
Karla GNSS campaignKarla Campaign
PRKV Permanent GNSS StationParaskevi Mytilini
Atalanti GNSS InstallationAtalanti Lokridos
National Observatory of Athens
NOA GPS Project
The monitoring of crustal deformation and its relation to seismicity is one of the new research areas of the National Observatory of Athens. Greece is one of the most active areas in the planet with crustal motions of the order of several cm per year, related to plate movements in the Eastern Mediterranean. Modern survey techniques, including space geodesy, have the sensitivity to detect motions of this magnitude over a few years time and thus can be used to address how Greece is deforming today.
Network Setup and History
NOA has obtained funding for permanent GPS observations through the EU project PREVIEW (www.preview-risk.com) and from national research programmes. The aim was to investigate the contemporary motions of the Western Greece over the time span of five years (2006-2011). One continuous GPS station comprising a Leica 1200GRXPro receiver has been installed in the island of Cephalonia (station VLS) on 13 February 2006. During 2007, three more receivers were installed on Lefkada and Corfu, respectively. The objective was to get results on time series, trajectories and velocities of crustal motion, as well as a geodetic strain rate field (see Ganas et al., 2012 for results).
Data Sampling and Telemetry
The current plan is to download 1-second sampled data (1 Hz) through the NOA telecom infrastructure on a daily basis, to maintain a 5-20 Hz data in the ring buffer, although there are also plans to collect data sampled 50 times per second (50 Hz) in a rotating buffer in advanced receivers (such as GR10 in PYLO), and to retrieve the high rate data after a large earthquake to support GPS seismology. The high rate (1 Hz - one sample per second) operations are also useful for the purpose of seismic early warning, damage mitigation, and to increase sensitivity to transient motions.
Ionian Sea Network
Western Greece is a key area for understanding the tectonic processes in the Africa- Eurasia collision zone. Previous work by Hollenstein et al., (2003) indicates compression between Apulia (Italy) and north-western Greece based on GPS measurements carried out between 1994 and 2001. On the other hand McClusky et al., (2000) found that the central, and southern Aegean is characterized by coherent motion (internal deformation of <2 mm/yr) toward the SW at 30 +/- 1 mm/yr relative to Eurasia. Thus, western Greece is characterized by a transitional strain field between shortening (west) and extension (east). Relative plate motion to the west of the Ionian Islands is accommodated by dextral motion along the Cephalonia transform fault (Louvari et al., 1999). Ganas et al., (2012) presented an analysis of 30-s GPS data from five (5) continuous stations of NOANET spanning the period 2007–2010. Their results show N-S crustal shortening onshore Lefkada island of the order of 2–3 mm/yr which is probably related to increased locking on the offshore Lefkada fault. They also calculated a large difference (1:3) in the principal strain rate amplitude between extension and shortening for the central Ionian Sea.
Links to 30-s RINEX daily data from the NOA GPS network can be found at the top menu of this page.
NOA supports an Open Data Policy. Data are provided to the Science community under the agreement that proper acknowledgements are made.
Ganas, A., Marinou, A., Anastasiou, D. Paradissis, D. Papazissi, K. Tzavaras, P. Drakatos, G., 2012. GPS-derived estimates of crustal deformation in the central and north Ionian Sea, Greece: 3-yr results from NOANET continuous network data, Journal of Geodynamics, ISSN 0264-3707, 10.1016/j.jog.2012.05.010.
Hollenstein C, Kahle HG, Geiger A, Jenny S, Goes S, Giardini D, 2003. New GPS constraints on the Africa-Eurasia plate boundary zone in southern Italy. Geophysical Research Letters, 30, 1935, doi:10.1029/2003GL017554.
Louvari E, Kiratzi AA, Papazachos BC, 1999. The Cephalonia Transform Fault and its extension to western Lefkada Island (Greece). Tectonophysics, 308 (1-2): 223-236.
McClusky S, Balassanian S, Barka A, Demir C, Ergintav S, Georgiev I, Gurkan O, Hamburger M, Hurst K, Kahle H, Kastens K, Kekelidze G, King R, Kotzev V, Lenk O, Mahmoud S, Mishin A, Nadariya M, Ouzounis A, Paradissis D, Peter Y, Prilepin M, Reilinger R, Sanli I, Seeger H, Tealeb A, Toksoz MN, Veis G. 2000. Global Positioning System constraints on plate kinematics and dynamics in the eastern Mediterranean and Caucasus. Journal of Geophysical Research-Solid Earth, 105 B3): 5695-5719.
Reception of first data from the VLS GPS station on 13.2.2006
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