Probabilistic earthquake hazard assessment for Ankara and its environs

Abstract

IntroductionAnkara is situated in the Central Anatolia Region (Figure 1) with a population of 4,842,136 in 2012, which is equivalent to 6.4% of the total population of Turkey. It is the second largest city in Turkey. There are 25 districts in Ankara and 96% of Ankara's population lives within the investigated area.The city is surrounded by 4 main fault lines: the North Anatolia Fault Zone (NAF) in the north, the Ezinepazarı Fault in the east, the Tuzgölü Fault Zone in the southeast, and the İnönü-Eskişehir Fault Zone in the west and south-west. These faults have the potential to create an earthquake with magnitudes of greater than 7.0 on the Richter scale (M ≥ 7.0). This is a very important seismic threat to Ankara. In addition to these main faults, there are numerous active faults within the province and its surroundings, including the city centre. These additional active faults can cause small-to medium-scale earthquakes (5.0 < M < 6.0) with possible losses.Few people believe that there is a seismic hazard in Ankara as the city has not experienced large devastating earthquakes in recent history. However, the active fault lines surrounding the city clearly pose a substantial threat, which this study set out to explore in detail. The Van earthquake of 23 October 2011 resulted in a strong political will for 'urban transformation' . It is also well known that most of the current building stock in Turkey is highly vulnerable to earthquakes and needs to be reconstructed or retrofitted. The probabilistic results published in this study can also be used by policymakers to prepare efficient hazard mitigation plans for Ankara. This paper provides background information on existing studies and details of the region. Next, the methodology is presented. Results and suggestions conclude the paper.Ankara is situated in a fourth-degree earthquake hazard zone [i.e. expected peak ground acceleration (PGA) is 0.1-0.2 g] according to the current official seismic hazard zonation map of Turkey, which was published in 1996. During the preparation of this map, Turkey was divided into 17 source regions. Using a probabilistic approach, the map was produced to show any 90% nonexceedance probability of PGA over a 50-year period.

Spectral‐based Probabilistic Seismic Hazard Analysis for Fethiye, Muğla

“…Statistical models are used to combine these data (Morell et al, 2020). Probabilistic methods have been proposed to reduce the effect of uncertainty in ground shaking which arises from considering parameters like hypocenter, time and magnitude of future earthquakes (Özmen and Erkan, 2014). Probabilistic seismic analysis tries to find the answers to questions of how often and how strongly the ground shaking will be.…”