Moho depth variations in North West Iran estimated from the Moho reflected phases

In this study, we investigated the Moho reflected phases and used them to estimate the spatial variation of the Moho depth in the northwestern Iran. The Moho reflected phases are secondary phases, which can be observed at the distance range between 20 and 185 km. We used 109 earthquakes whit depth shallower than 35 km occurred from 1996 to 2017 and collected the approximate travel time of 188 PmP and 140 SmS high quality phases recorded by 36 seismic stations. We used the differential travel time of direct and the Moho reflected phases to estimate the depth of Moho. The results of the reflected phases PmP and SmS are very similar in character. Although differences are also observed, especially in the northern part of the studied area where reflection points are not well distributed. The results of the inversion of P data are more reliable owing to the accuracy of the picking of P- compared to S- phases. According to the results, the average Moho depth is about 45 km in the north and south of the North Tabriz Fault, decreasing to 43.5 km towards the eastern and northwestern parts of the study area.