Preliminary Results From the COMET CGPS Network in Greece

HR: 0800h
AN: G21A-0114 [Abstracts]
TI: Preliminary Results From the COMET CGPS Network in Greece
AU: * Floyd, M A
EM: Michael.Floyd@earth.ox.ac.uk
AF: Centre for the Observation and Modelling of Earthquakes and Tectonics, Department of Earth Sciences, Parks Road, Oxford, OX1 3PR United Kingdom
AU: Nocquet, J
AF: Centre for the Observation and Modelling of Earthquakes and Tectonics, Department of Earth Sciences, Parks Road, Oxford, OX1 3PR United Kingdom
AU: Nocquet, J
AF: Laboratoire de Recherche en GＰdＴie, Institut GＰgraphique National, 6-8 avenue B. Pascal, Marne-la-VallＦ, F-77455 France
AU: Billiris, H
AF: Higher School of Rural and Surveying Engineering, Department of Topography, Higher Geodesy Laboratory, 9 Heroon Polytechniou, Zographos, Athens, 15773 Greece
AU: Paradissis, D
AF: Higher School of Rural and Surveying Engineering, Department of Topography, Higher Geodesy Laboratory, 9 Heroon Polytechniou, Zographos, Athens, 15773 Greece
AU: England, P
AF: Centre for the Observation and Modelling of Earthquakes and Tectonics, Department of Earth Sciences, Parks Road, Oxford, OX1 3PR United Kingdom
AU: Parsons, B
AF: Centre for the Observation and Modelling of Earthquakes and Tectonics, Department of Earth Sciences, Parks Road, Oxford, OX1 3PR United Kingdom
AB: The Hellenic subduction zone accommodates the convergence between the oceanic lithosphere of the African plate and the extending continental lithosphere of the Aegean. Former studies (e.g. Jackson & McKenzie, 1988) concluded that earthquakes can only account for 10% of the relative motion, suggesting that the subduction is in a stable sliding state. In contrast, some authors (e.g. Pirazzoli et al., 1982), using the Holocene geological record, suggested that large earthquakes (M$>$8) may have occurred in historical times, indicating that the zone may be locked. In order to discriminate between these two views, a network of permanent GPS stations is being developed throughout the south-west Aegean region to monitor the strain accumulation and release along the interface and over the surrounding region, and potentially detect aseismic slip events as seen in others subduction zone (e.g. Dragert et al., 2001). We analyse the CGPS network together with a subset of IGS and EUREF sites in Europe on a routine basis to derive the daily solutions and time series. We present the analysis of the time series and results for sites having about 18 months of data. Preliminary estimates of velocities suggest that the current convergence rate accommodated across the Hellenic trench is $\sim$35 mm/yr, in agreement with McClusky et al. (2000, 2003). No shortening perpendicular to the trench is found between sites located in the southern Peloponnese and Crete relative to sites located further landward. The results are compared to the seismicity of the region in order to reassess the ratio of seismic and aseismic deformation. Moreover, the geodetic results confirm the presence of strike-parallel spreading along the arc at $\sim$3.5 mm/yr between south-western Peloponnese and western Crete, which correlates with several extensional structures described by Armijo et al. (1992) and earthquake focal mechanisms.
DE: 8107 Continental neotectonics
DE: 8158 Plate motions--present and recent (3040)
DE: 1242 Seismic deformations (7205)
DE: 1299 General or miscellaneous
SC: Geodesy [G]
MN: 2004 AGU Fall Meeting