Re-evaluation of Tsunami Hazard in Mamara Sea Generated from the Combined Earthquake and Landslide Sources Focusing on Istanbul, Turkey

Abstract:

This study aimed to re-evaluate tsunami hazard in Marmara Sea from earthquake and submarine landslide focusing on the coastal area of Istanbul. For the fault-generated tsunami, the seismic rupture can be propagated along the North Anatolian Fault (NAF) which have evidenced historical tsunami in Marmara Sea. Based on previous research studies, future scenarios are expected to generate tsunami as well as submarine landslide could be triggered by seismic motion which consider fault-generated tsunami and landslide-generated tsunami individually. However, this study want to simulate tsunami propagation generated from the combining earthquake-landslide sources. Therefore, the evaluation of tsunami hazard was discussed in both of the individual case and the combining case of earthquake and submarine landslide through numerical modelling of tsunami wave with mesh size 90 m of bathymetry data. A two-layer numerical model was employed to simulate the landslide-generated tsunami by modeling the interaction between tsunami and submarine landslide with different volume of initial slide. First, tsunami propagation was generated from earthquake sources of Rupture E in the eastern basin and Rupture W in the western basin of Marmara Sea with fault slip 5 m. For Rupture E and Rupture W, maximum tsunami height at shore shoreline could reach 3.4 m and 2.8 m respectively along the coastal area of Istanbul. For combining Rupture E and Rupture W, maximum tsunami height could reach 3.8 m which was a little higher than that of Rupture E. Then, tsunami propagation was generated from landslide sources in the southern neighborhood of Istanbul near Rupture E. For landslide volume of 0.15 m³, 0.6 m³, and 1.5 m³, maximum tsunami height at shore shoreline could reach 3.7 m, 6.9 m and 8.7 m respectively along the coastal area of Istanbul. It was shown that maximum tsunami height from landslide sources was higher than that from earthquake sources depending on the volume of initial slide significantly. Lastly, the combining earthquake-landslide sources are being processed to generate tsunami propagation in order to evaluate tsunami hazard, in which damage is being expected more serious than the landslide-generated tsunami. This combination can be a possible evaluation of tsunami hazard for future scenarios in Marmara Sea.