Tectonic and neotectonic of the Hamadan city and its surroundings with implication to seismotectonic of the district

The study area is located in the Northeast of Alvand batholite and 130 km far from Zagros tectonic and seismotectonic belt. This area is situated on sanandaj- sirajan metamorphic belt (fore – arc basin), west of the Iran, tectonically classified as an active zone of Iran. Investigations on Hamedan bedrock and its surroundings indicate that not all of the urban constructions are built on the bedrock but in most cases they are built on the unconsolidated Quaternary sediments, which are spread out from the Alvand slopes to the east and southeast. The bedrocks under the sediments in the study area are slates of the mentioned metamorphic belt.Tectonic study on Hamedan region resulted recognition of several faults in southeast and inside the Hamedan city and in Alvand mountain; These faults are classified into two grups: pre-Quaternary and Quaternary faults. Quaternary faults (the main subject of this paper) appear as a fault system which are long and linear and affect geological structures and older faults and are correlated with main structure of zagross (NW – SE) in west of Iran. The objective of this research is to study seismic faults, distributed in the Hamedan Province, and their role on seismotectonic characteristics of the area. Field data are used for recognizing and interpretation of faults mechanism, with using of these data, the maximum expected acceleration is computed based on the waning model. The Hamedan region is surrounded with seismic faults such as Zagros strike- slip faults in the west-Northwest, Tabriz fault in the north, and Avaj fault in the north east, so it can be concluded that the recognized faults at Hamedan suburbs have important roles in earthquake potential of this region, and can intensify it.