Investigation of Active Fault Scarps by Means of Geophysical Prospecting Methods, Javakheti Fault Case, Georgia

Current presentation concerns investigation of Javakheti seismically active fault (Georgia, South Caucasus region) by means of Geophysical prospecting methods, carried out during the past two years. The named fault represents the major seismo tectonic structure at Javakhety volcanic highland. Fault segments at some places are well expressed on surface and several of those were mapped even during the Geologic surveys carried in 60-70's of previous century, though not recognized as a single structure. Detailed study of seismically active faults is an important component for proper seismic hazard assessment. Fault scarps, an evidence of fault's activity, are expressed on the earth surface as a result of accumulated rapid displacements due to earthquakes. Geomorphologic studies could provide us with rather general information about the fault, while much more information can be derived from paleo trenching and borehole coring. Unfortunately these methods are quite expensive and time consuming, requiring significant technical and man resources. Shallow Geophysical prospecting methods seems to be a valuable addition to above mentioned techniques. In our case extensive Geophysical prospecting surveys, preceded by Geomorphologic and Geologic Surveys have provided valuable information, first of all for correct identification of fault but also regarding the fault dynamics and internal structure of scarps. During this year geophysical studies were followed by paleo trenching at two locations, preliminary selected based on Geophysical data. Both trenches appeared to be successful, were revealed tracks of several paleo earthquakes currently under processing. Studies were also focused on development of Geophysical prospecting techniques and Interpretation of the results. During the past two years fault scarps were studied by means of Seismic prospecting methods (refracted waves, 2D tomography and surface waves), electric resistivity and Ground Penetrating Radar (200 and 80 MHz antennas). Al these rather inexpensive methods were applied along the same profiles, supplementing each other and providing favorable conditions for analysis and interpretation. As mentioned above, two of the profiles were excavated providing ground truth data and giving more confidence two our interpretations. Presumably, the approaches developed and accumulated experience could be of interest for future studies.