Evaluating the seismic potential for areas around Tabriz metro line 2, NW Iran

The present study was performed to evaluate the seismic potential for areas around Tabriz metro line 2 (TML2) by using the data obtained from the historical earthquakes, the recorded data of instrumental earthquakes, and the 1:100,000 scale, geological maps of the study area. Considering that the project of TMl2 is under construction, the results of this research can be used by the Tabriz Urban & Suburban Railway Operation Co for the construction of this line. A study of the seismic history of the Tabriz area shows that the region has been seismically active since 634 A.D. Based on the instrumental earthquake data, at least 354 earthquakes with magnitude (M ≥ 3) have occurred in the Tabriz area since 1907. The average focal depth of earthquakes in the region is 23 km, representing shallow earthquake sources for the region. The north Tabriz fault (NTF) is one of the most active at a close distance from TML2. Furthermore, its reactivation in the future will generate an earthquake of magnitude (Ms = 6.1), and maximum horizontal ground acceleration of (Ra = 0.34 g) in the areas along TML2. Considering the short distance of this fault to the city of Tabriz and the TML2 and the report of several destructive historical earthquakes along this fault, its reactivation can have seriously damaging effects on Tabriz metro line 2. However, if the tunnels and stations of TML2 are designed by observing all of the engineering codes and designing criteria. Also, their construction being done with all construction standards and an appropriate method by using high-quality construction materials can prevent any serious damage to line 2 of the Tabriz metro during future earthquakes. Finally, as there is a likelihood of large and dangerous earthquakes in Tabriz, evaluating the seismic potential for areas around Tabriz metro line 2 should be included in future construction planning of TML2 and other metro lines.