From Seismic Sources to Engineering Demand Parameters: An Interdisciplinary Framework for Estimation of Seismic Losses in Urban Regions

Risk mitigation in urban regions starts with identification of potential seismic losses in future earthquakes. Estimation of seismic losses concerns a wide range of authorities varying from geophysical and earthquake engineers, physical and economic planners to insurance companies while the process naturally involves inputs from multiple disciplines. In this study, we present a city-level model where potential seismic losses are expressed in terms of regional seismic hazard, local soil conditions and local building vulnerabilities. The main components of the study are probabilistic and deterministic seismic hazard assessment and estimation of potential ground motions, regional building vulnerability, fragility information, and loss functions. As the study area, Erzincan, a city on the eastern part of the North Anatolian Fault zone is selected. Located within a triple conjunction of major fault systems within a basin structure, and experienced two major events within the last century in 1939 (Ms=8.0) and in 1992 (Mw=6.6), this city has significant hazard potential. We present the results in terms of key components such as construction of a 2D velocity model, ground motion simulations of past earthquakes and scenario events, site-specific probabilistic seismic hazard analyses and fragility functions derived using regional building characteristics along with simulated regional ground motion data. The verification of the model is performed through comparisons of estimated mean damage ratios for the 1992 earthquake with the corresponding observed values. The consistency of the estimated and observed values points out the significance of using locally-derived models for every component of loss estimation process