ASSESSING SEISMIC RISK IN RETFALA NOVA, OSIJEK
The Croatian territory, as part of the Mediterranean-trans-Asiatic belt, experiences pronounced earthquake activity. Seismic risk is the expected damage caused by earthquakes to buildings, measured both in social and economic losses, which can be described through seismic hazard, seismic vulnerability, and exposure. The city of Osijek is located in the eastern part of Croatia, and Retfala Nova is a residential settlement in the western part of the city. An important step in assessing earthquake loss is defining the exposure, so we created a form used to collect information on buildings and make a building database. In this paper, we estimated seismic vulnerability based on the capacity spectrum method, which involves constructing fragility curves and converting them to damage probability matrices, as well as constructing capacity curves.
A Contribution to a UHS-Based Seismic Risk Assessment in Croatia—A Case Study for the City of Osijek
Due to increases in the number of inhabitants and their concentrations in densely populated areas, there is a growing need in modern society to be cautious towards the impact of catastrophic natural events. An earthquake is a particularly major example of this. Knowledge of the seismic vulnerability of buildings in Europe and around the world has deepened and expanded over the last 20 years, as a result of the many devastating earthquakes. In this study, a review of seismic risk assessment methods in Croatia was presented with respect to the hazard, exposure, and vulnerability of buildings in the fourth largest city (Osijek) in Croatia. The proposed algorithm for a detailed risk assessment was applied to a database and is currently in its initial stage.
A comparative study of different PGA attenuation and error models: Case of 1999 Chi-Chi earthquake
Abstract In order to evaluate the horizontal peak ground acceleration (HPGA) during earthquakes, the author studies the respective efficiency of two existing attenuation models [Mebarki, A., 2003a, Risques sismiques: aleas, vulnerabilite et aide a la decision par cartes SIG. Proceedings of International Conference on “Risks, Vulnerability and Reliability in Construction. Towards a reduction of disasters”. ISBN: 9961-891-01-5, pp. 82–97. Algiers, October 11–12, Mebarki, A., 2003b. Proposal of a parametric attenuation model and comparison with some worldwide earthquakes. VIIo Congreso Venezolano de Sismologia y Ingenieria Sismica, Barquisimeto, Venezuela. November 12–13, (CD-ROM), Mebarki A., 2004. Modele d'attenuation sismique: prediction probabiliste des pics d'acceleration, RFGC — Revue Francaise de Genie Civil, Hermes Ed., 8 (9–10), 1071–1086]. A comparative study of their performances is done in the case of 1999 Chi-Chi earthquake (Taiwan). The reported PGA (Peak Ground Accelerations) values correspond to hypocentral distances ranging from 15 up to 180 km with observed acceleration peaks ranging from (0.04 g) up to (1.16 g). The author considers two kinds of probabilistic distributions for the error model in order to describe the uncertainty and the variability that affect the values of the PGA: a Gamma distribution and a Log-normal distribution. The adopted error models assume that the variability of the PGA is such that its coefficient of variation is equal to 55% [Mebarki, A., 2003a. Risques sismiques: aleas, vulnerabilite et aide a la decision par cartes SIG. Proceedings of International Conference on “Risks, Vulnerability and Reliability in Construction. Towards a reduction of disasters”. ISBN: 9961-891-01-5, pp. 82–97. Algiers, October 11–12, Mebarki, A., 2003b. Proposal of a parametric attenuation model and comparison with some worldwide earthquakes. VIIo Congreso Venezolano de Sismologia y Ingenieria Sismica, Barquisimeto, Venezuela. November 12–13, (CD-ROM), Mebarki, A., 2004. Modele d'attenuation sismique: prediction probabiliste des pics d'acceleration, RFGC — Revue Francaise de Genie Civil, Hermes Ed., 8 (9–10), 1071–1086]. The obtained results show that both attenuation models provide adequate values of the PGA when a Gamma distribution is adopted for the error model. The attenuation models efficiency decreases slightly when a Log-normal distribution is adopted for the error model.