Probabilistic Seismic Hazard Assessment of Seismically Induced Landslide for Bakacak-Dϋzce Region

Earthquake induced slope instability is considered as one of the major sources of the earthquake hazards, especially in the near fault regions. Simplified tools as Newmark's Sliding Block (NSB) analogy are commonly used to represent the slope stability during ground shaking since the outcome of this analogy is quantitative, larger NSB displacement values indicate higher seismic slope instability risk. Recently, empirical NSB displacement prediction models based on single or multiple ground motion intensity measures are proposed to analyze the slope instability hazard in a probabilistic manner. Within the contents of this study, the most compatible NSB displacement model with the regional ground motion characteristics is selected and incorporated into the vector-valued probabilistic seismic hazard assessment framework. The NSB displacement hazard curves are constructed for Asarsuyu Region where a large-scaled seismically induced landslide was observed during 1999 Duzce earthquake. The NSB displacement hazard results are compared with the dynamic analysis results that were conducted immediately after the earthquake and measured slope displacements

Planar Seismic Source Characterization Models Developed for Probabilistic Seismic Hazard Assessment of Istanbul

This contribution provides an updated planar seismic source characterization (SSC) model to be used in the probabilistic seismic hazard assessment (PSHA) for Istanbul. It defines planar rupture systems for the four main segments of the North Anatolian fault zone (NAFZ) that are critical for the PSHA of Istanbul: segments covering the rupture zones of the 1999 Kocaeli and Düzce earthquakes, central Marmara, and Ganos/Saros segments. In each rupture system, the source geometry is defined in terms of fault length, fault width, fault plane attitude, and segmentation points. Activity rates and the magnitude recurrence models for each rupture system are established by considering geological and geodetic constraints and are tested based on the observed seismicity that is associated with the rupture system. Uncertainty in the SSC model parameters (e.g., b value, maximum magnitude, slip rate, weights of the rupture scenarios) is considered, whereas the uncertainty in the fault geometry is not included in the logic tree. To acknowledge the effect of earthquakes that are not associated with the defined rupture systems on the hazard, a background zone is introduced and the seismicity rates in the background zone are calculated using smoothed-seismicity approach. The state-of-the-art SSC model presented here is the first fully documented and ready-to-use fault-based SSC model developed for the PSHA of Istanbul