The EGELADOS Project
The EGELADOS project is a passive seismic experiment in the Hellenic Subduction Zone that is conducted within the framework of the Collaborative Research Center 526 "Rheology of the Earth" at Ruhr-University Bochum. Its aim is to investigate earthquake activity and earth structure along the forearc and in the island arc of the Hellenic subduction zone. Besides scientists from Ruhr-University Bochum, several scientists from universities and research institutions in Greece, Turkey and Germany collaborate within the project. These institutions are:
* University of Thessaoloniki, represented by Prof. C. Papazachos,
* Istanbul Technical University (ITU), represented by Prof. T. Taymaz,
* National Observatory of Athens (NOA), represented by Dr. G. Stavrakakis,
* Technical University Chania on Crete, represented by Dr. Vafidis,
* GeoForschungsZentrum (GFZ) Potsdam, represented by Prof. R. Kind,
* University of Hamburg, represented by Prof. T. Dahm.
Using seismic waveforms from a dense, temporary network of broad-band ocean-bottom and land seismographs to be deployed on the Peloponnes peninsula, the South-Aegean Sea and adjacent Turkey, we will perform a detailed investigation into the elastic and anelastic properties of the Hellenic subduction zone. Particular targets will be (1) the contact zone between the subducted African lithosphere and the overlying Aegean mantle, including crust and uppermost lithosphere beneath the forearc, (2) the mantle wedge above the slab extending from the Cretan Sea to beyond the volcanic arc of the Cyclades and (3) lateral variations in properties of the slab itself. Target (1) is motivated by the finding that parts of the contact zone are aseismic indicating weak coupling and low stress. Exhumed HP-LT rocks indicate the existence of a low-viscosity subduction channel within which material transported downwards into the mantle during subduction may be pushed back to subcrustal levels by forced return flow. With target (2) we aim at mapping structural connections between the active volcanoes at the surface, fluids rising from the subducted slab and dehydration-related seismicity. Target (3) is selected to test the hypothesis that along-strike variations of slab properties cause the lateral variation of the dip and the segmentation of the downgoing slab. The search for detailed structure in these target areas will be supplemented by a high-resolution tomographic image of the whole region providing us with the necessary structural background information. Such a model is also essential for accurate earthquake location. Primary method of investigation will be the modelling and inversion of seismic waveforms from regional earthquakes based on Born scattering theory, coupled-mode scattering theory and fully numerical modelling.