1 Department of Reinforced Concrete Structures, Technical University of Civil Engineering, Bucharest, Romania E-mail: lungud@hidro.utcb.ro ; aldea@hidro.utcb.ro 1 ENGINEERING, STATE & INSURANCE EFFORTS FOR REDUCTION OF SEISMIC RISK IN ROMANIA Dan LUNGU, Alexandru ALDEA and Cristian ARION 1 SUMMARY The paper describes procedures and actions adopted for assessment and reduction of seismic risk in Romania. The study is based on following information: (i) Design provisions for earthquake resistance of structures during 6 generations of seismic codes (1941 - 1998); (ii) Probabilistic hazard assessment in the influence area of subcrustal (60÷170 km) Vrancea source in Eastern Europe; (iii) Classification of model buildings of the Romanian building stock (iv) Vulnerability curves for typical RC and masonry model buildings and (vi) Expertise reports for the most damaged by earthquakes buildings in Bucharest. Using FEMA/HAZUS methodology (1997), the paper presents Guidelines for selection of the damage function for building structures in Romania, based on building age and seismic zonation map valid during construction of the building. Two Governmental countermeasures documents aiming at providing safety to strong earthquakes for the building stock of Romania are presented: Order No.6173/NN/1997 of the Minister of Public Works and Land Planning and Governmental Ordinance HG 597/1998 providing, from state funds, about 20 Millions US $ per year for retrofitting the most damaged buildings in Bucharest. 1. INTRODUCTION Within the last 60 years, Romania was threatened by 4 strong Vrancea events: Nov.10, 1940 (Gutenberg-Richter magnitude M=7.4, focal depth h=150 km), March 4, 1977 (M=7.2, h=109 km), Aug. 30, 1986 (M=7.0, h=133 km) and May 30/31, 1990 (M=6.7/6.1 h=91/79 km). In the epicentral area, acceleration of 0.3g was recorded at Focsani during the 1986 event. In the soft soil condition of Bucharest, at 105 km from the epicentre, a peak acceleration of 0.2g and a 1.6 s long predominant period of soil vibration were observed during the 1977 event. The estimation of losses after the 1977 earthquake indicates 2.05 Billion US $. 2/3 of the total losses were in the capital city, Bucharest, where more than 1400 people died and 32 RC tall buildings collapsed. The 1977 direct losses and indirect consequences mark probably the starting point of economical decay of Romania during the last decades. The losses explain the present interest and concern of civil engineering community, Romanian Government and international insurance industry for assessment and reduction of seismic risk in Romania. 2. SEISMIC HAZARD ZONATION FOR VRANCEA SOURCE IN ROMANIA The Gutenberg-Richter relationship for Vrancea large (M≥6.0) magnitude recurrence [Lungu et al., 1995]: log n(≥M) = 3.49 - 0.72 M (1) was modified to take into account the source maximum credible magnitude using Hwang & Huo (1994) model. The average number per year of events with magnitude greater than or equal to M is [Elnashai, Lungu, 1995]: n M e e e M M M M M ( ) . . . ( ) . ( ) max max ≥ = - - - - - - - 8 036 1 658 1 658 1 658 1 1 0 (2) where M max is the maximum credible magnitude of the source and M 0 = 6.0 is the threshold lower magnitude.