[S04-4] Historical and macroseismic studies of earthquakes IV

[S04-4-04] Historical Earthquake of Georgia

^○Nino Tsereteli, Otar Varazanashvili (Institute of Geophysics of I. Javakhishvili State University, Tbilisi, Georgia)

This work discusses the historical earthquakes that occurred in Georgia during the period between 1250 BC and 1900, and the problems associated with their study. Many monuments of cultural heritage and architectural buildings have the signs of seismic effects. Despite the wide range of analytical work done in compiling historical earthquake catalogues some arguable interpretation of the data on certain historical earthquakes, inaccuracies in determining the parameters were still preserved in these fundamental studies. In addition, significant information existent in numerous original sources has remained undeveloped. They can provide important data for the quantitative parameterization for the newly discovered historical earthquakes Georgia. It is noteworthy that only a little quantity of geologic, geomorphologic and archaeological data was used for the parameterization of historical earthquakes in Georgia in each of the above mentioned catalogues. Methodology for creating a catalogue of historical earthquakes is based on transformation of descriptive data of damage in terms of macroseismic intensity range, as well as on determination of its location, magnitude, focal depth and their errors. This parameterized catalogue represents the full database of historical earthquakes that affect the territory of Georgia. The summarized map of the distribution of maximum damage in the historical period (before 1900) on the territory of Georgia clearly shows the main features of the seismic field during this period. In particular, in the axial part and the southern slope of the Greater Caucasus there is a seismic gap, which was filled in 1991 by the strongest earthquake and its aftershocks in Racha. In addition, it is also obvious that very high seismic activity in the central and eastern parts of the Javakheti highland is not described in historical materials and this fact requires further searches of various kinds of sources that contain data about historical earthquakes.