Probabilistic seismic hazard evaluation of eastern Anatolia observatory

The Eastern Anatolia Observatory (DAG), to accommodate a 4-m telescope, is under construction in the city of Erzurum at

Karakaya Peak of the Palandöken Mountain Range. Owing to the vulnerability of the telescope and its optical components

to earthquakes and the high demand for pointing accuracy for quality astronomical observations, the seismic hazard needs to

be reliably determined before any design and construction work begins. A relevant rectangular zone, extending 250 km from

the observatory in each direction, is selected as the study area. Then, the seismic hazard at the DAG site is estimated by using

the probabilistic hazard analysis method. Using diferent magnitude scales, several earthquake catalogues are recompiled by

converting them into a uniform moment magnitude (Mw) scale, and the seismic sources that could afect the study area are

determined. The results are aggregated for epistemic uncertainties using the logic-tree method. Finally, peak ground acceleration (PGA) values are obtained for two recurrence periods corresponding to two diferent design levels (operating basis and

design basis earthquakes) using two diferent ground motion attenuation models. The disaggregation of the seismic hazard

permits association of the PGA estimates with various faults. Disaggregation also provides source informa