A new velocity field for Greece: Implications for the kinematics and dynamics of the Aegean

Abstract

[1] A new set of geodetic velocities for Greece and the Aegean, derived from 254 surveymode and continuous GPS sites, is used to test kinematic and dynamic models for this area of rapid continental deformation. Modeling the kinematics of the Aegean by the rotation of a small number (3-6) of blocks produces RMS misfits of ∼5 mm yr −1 in the southern Aegean and western Peloponnese, indicating significant internal strain within these postulated blocks. It is possible to fit the observed velocities to within 2-3 mm yr −1 (RMS) by models that contain 10 or more blocks, but many such models can be found, with widely varying arrangements of blocks, that fit the data equally well provided that the horizontal dimension of those blocks is not larger than 100-200 km. A continuous field of velocity calculated from the GPS velocities by assuming that strain rates are homogeneous on the scale of ∼120 km fits the observed velocities to better than 2-3 mm yr −1 (RMS), with systematic misfits, representing more localized strain, confined to a region approximately 100 × 100 km in size around the western Gulf of Corinth. This velocity field accounts for the major active tectonic features of Greece and the Aegean, including the widespread north-south extensional deformation and the distributed strike-slip deformation in the NE Aegean and western Greece. The T axes of earthquakes are aligned with the principal axes of elongation in the geodetic field, major active normal fault systems are perpendicular to those axes, and ∼90% of the large earthquakes in this region during the past 120 years took place within the areas in which the geodetic strain rate exceeds 30 nanostrain yr −1 . These observations suggest that the faulting within the upper crust of the Aegean region is driven by forces that are coherent over a scale that is significantly greater than 100 km. It is likely that those forces arise primarily from differences in gravitational potential energy within the lithosphere of the region. Citation: Floyd, M. A., et al. (2010), A new velocity field for Greece: Implications for the kinematics and dynamics of the Aegean,

An optimal geodetic dynamic reference frame realization for Greece: Methodology and application

“…Unfortunately, the major discrimination occurs in the Aegean Sea as extensively described in many previous publications, [e.g. Floyd et al 2010]. …”

“…Since the early 1970s several studies [McKenzie 1972, Le Pichon 1995, McClusky et al 2000, Nyst and Thatcher 2004, Reilinger et al 2006, Floyd et al 2010 attempted to determine the number and the block boundaries of the microplates in the Aegean Sea. The number of the estimated blocks increases at the most recent studies and varies from two [McKenzie 1972] to fifteen [Floyd et al 2010] microplates. The block boundaries cannot be defined with high accuracy for geodetic applications and consequently the realization of the local reference frame (based on microplates) it is not feasible.…”

Chapter 2 Active tectonics of Myanmar and the Andaman Sea

“…This framework, developed for Tibet, can successfully reproduce the style of deformation and long-wavelength GPS-derived velocity fields in many actively deforming areas when appropriate boundary conditions are applied (e.g. Floyd et al 2010).…”

Time series analysis of the NOANET CGPS stations

“…As a result the area exhibits high seismicity. Relative motion of these plates accumulates stress in the lithosphere, causing observable crustal deformation (McClusky et al, 2000;Ganas and Parsons, 2009;Floyd et al, 2010). Earthquake activity occurs due to tectonic stress release along both, the crustal faults and the Mediterranean-Eurasia plates' interface, a fact that makes the study of crustal deformation an interesting and essential issue.…”

“…During the last decade, a number of groups conducted research on the fragmentation of the upper crust in microplates or continental blocks (e.g. Avallone et al, 2004;Nyst and Thatcher, 2004;Reilinger et al, 2006;Floyd et al, 2010) and on mapping crustal motions and interseismic velocities in the central part of the country (e.g. Briole et al, 2000;Bernard et al, 2006;Hollenstein et al, 2008).…”