THE SEISMIC MONITORING OF STRONG EARTHQUAKES - A SPECIFIC FACTOR FOR PROTECTION OF THE ENVIRONMENT

till now. Some of them can be seen at the ruins of the ancient town of Perperikon that are cleared out during the last years. Displacements at the beginning of the “throne-room” showing subsidence of the east side (block) about

20 cm were observed. Displacements of tectonic origin were established into the Quaternary deposits at two places on the scarps of the cart-road to Perperikon. The first one marks a rupture in a probable direction 45-80º; in the second case the direction is to

130° with a strike-slip component [4]. Professionals from the Bulgarian Academy of Sciences analyzed and summarized the damage observations from their inspection in the epicentral area of the earthquake, taking into account the physical characteristics derived from the SMS records in the region. They published their findings and conclusions [2], [3], [4] and submitted their recommendations for rehabilitation of the affected building stock to the local authorities. EARTHQAKE: NE of Kurdjali, Feb., 2006. SETTLEMENT: Chiflik Destruction of the chimney, fallen plaster from the facade and broken window panes. Active fault, well-defined outlines on the hill above the NW facade of the same building TYPE OF STRUCTURE: (C) Building of mixed type CLASSIFICATION OF DAMAGES:

2 3 4 5  Fig. 6 Post-Earthquake effects SUMMARY AND FINAL REMARKS Continuous seismic monitoring of the strong earthquakes, affecting the territory of Bulgaria is of vital importance for the sustainable economic development of our country. Hence, the operation of the SMS, the accumulation and utilization of the processed SGM records and the respective databank is indispensable tool and an adequate background for any seismic–resistant design and construction of buildings, engineering structures and life-line systems. This is a prerequisite for reliable earthquake risk reduction and effective disaster prevention policy of any modern state - therefore a specific factor for protection of the environment. According the latest information there are currently a total number of more than 3,500 accelerometric stations in the Euro-Med region. About 300 of them belong to Turkey, 160 to Greece, 160 to Romania. So far the Digital Network of Bulgaria consists of 30 units deployed in the seismically active regions of our country. The setting-up, maintenance and exploitation of a modern national network for registration of SGM, covering the area of the country with sufficient density is a large-scale task, demanding considerable resources (human and financial). The new DN introduced in 2004 is only the first step in the process of modernization of the SMS. Hitherto, seismically most active regions in Bulgaria have been covered by modern equipment under minimal density. The team running the National SMS is determined to develop it by: increasing its density with special emphasis on structures and installations of high potential risk for the population/environment and life-line systems like bridges, tunnels, elevated highways, underground railways, pipelines etc.; making use of contemporary solutions for data processing and analysis, telecommunication, data storage and dissemination; diversifying its functions (maintenance, data acquisition, processing, analysis and assessment, data storage and dissemination, provision of key parameters for early warning and control of sensitive installations etc.; integrating with the networks of the neighbouring Balkan countries, and participating in the creation of a reliable strong-motion databank with the relevant seismological, geological, instrumental and other specific parameters to ensure an efficient international data exchange in the European area. All this would be achieved by the cooperation and collaboration of interested organizations, including such from abroad via international projects. REFERENCES

Simeonov, S., Hadjiyski, K. et al.: Reconstruction and Modernization of the National System for Registration, Analysis and Evaluation of Strong Ground Motions. CLSMEE –Report (Dec. 2004).

Hadjiyski, K., Simeonov, S.: Characteristics of the Md=4.5 Earthquake of 20-th. Feb. 2006 in the region of Kardjali and the following aftershocks. International Conf. on Civil Eng. Design and Construction, pp. 314÷319, Sep. 2006, Varna, Bulgaria.

Hadjiyski, K., Glavcheva, R.: The Md=4.5 Earthquake of Feb. 20, 2006 in the region of Kardjali –macroseismic survey in the epicentral zone. International Conf. on Civil Eng. Design and Construction, pp. 307÷313, Sep. 2006, Varna, Bulgaria.

Glavcheva, R., Dobrev, N., Hadjiyski, K. et al.: The 2006 seismic activation in the Eastern Rhodopes (Mts) –Kardjali area and some generalization on geological features in the region. National Conf. –GEOSCIENCES 2006 with international participation, pp. 315÷319, Dec. 2006, Sofia, Bulgaria.