Advances in earthquake risk assessment and hazard reduction for large inventory of structures with high characteristic variability

Seismic risk assessment and hazard mitigation for urban infrastructures located in seismic regions is a challenge faced by many countries around the world, especially those with infrastructures known for their variability in seismic resistance and quality of construction. Two recent major earthquakes that hit the densely populated urban areas in Northwest Turkey resulted in a large-scale destruction and loss of life. Scientific studies indicate that the probability of occurrence of another severe and destructive earthquake along the North Anatolian Fault near Istanbul is quite high in the next thirty years. This situation presents a serious threat to the large building stock and their occupants, lifelines, and critical facilities in Istanbul and adjacent areas. The criticality of the situation is exacerbated by the fact that the existing structures in these areas are known to have high variability in their seismic resistance, which makes it difficult to estimate the potential losses in case of a major earthquake. Limited time and funds do not allow for a detailed evaluation of the entire inventory of structures according to seismic codes. Thus, there is an urgent need for a systematic strategy that will allow for a reliable assessment of the seismic hazard risk of existing structures through an effective and economical methodology. Prioritization of these structures according to their hazard risk, and implementation of the necessary mitigation measures are required. This paper presents the methodologies and advances in large-scale seismic risk evaluation and hazard reduction, and identifies the needs for further research.