Monitoring vertical displacements by precise levelling: a case study along the Tuzla Fault, Izmir, Turkey

The Aegean region and its surrounding area of Western Turkey is one of the most seismically active and rapidly deforming regions in the world. The study area, Izmir, is located between 26 degrees 15'-28 degrees 20 ' E longitude and 37 degrees 45'-39 degrees 15' N latitude in the Aegean region of Western Anatolia. The Tuzla Fault passes through Izmir, which is the third largest city in Turkey. In this study, we approach the problem of estimating and investigating the vertical displacements along the Tuzla Fault using a network of high precision levelling line. We established a levelling route with eight benchmarks, along the fault line. Six precise levelling campaigns were performed between 2009 and 2012, and the collected data in the surveying campaigns were processed by using the least-squares adjustment method and global testing in order to evaluate the vertical displacement. The results of the precise levelling indicated that the vertical displacements in the study area are not as significant in this period as were expected. However, compared with previous studies conducted in the same area, this study is different not only from the technique applied, but also it is carried out for the first time.