SEISMOTECTONICS OF SAYDOON DAM SITES IN THE IZEH FAULT ZONE,SW OF IRAN

The effects of Quaternary, Holocene, and historic seismotectonics are of greatest relevance to dam construction. These effects pose the greatest hazards where the magnitudes of earthquakes are large and their hypocenters are shallow. The seismic hazard is the most severe hazard to be considered in the design of large dam projects located in high seismic areas. The earthquake hazard is a multiple hazard, so a thorough investigation is needed for the estimation of the ground motion of the different design earthquakes. This paper gives an overview on the seismotectonic setting of Saydoon dam sites in the context of Izeh fault zone, and the relevant design aspects of the selected dam sites. The main concern of the seismotectonic study is related to the identification and assessment of movements in the dam foundation during strong earthquakes. The presence of active faults and the possibility of movements along discontinuities in the footprint of the dam during strong earthquakes may have severe consequences on the selection of the dam type and the dam site.The Izeh Fault Zone in which the studied dam sites are located, is a north south-trending structure specified by very intense folding and thrusting as well as medium to high seismicity and has been active during the Mid-Cretaceous and remained active into the Tertiary. Along this transverse fault zone, some evidences of dextral shear deformation structures such as dextral bending of fold axes, strike slip duplexes, and en-echelon folds are developed.

Keywords:

Seismotectonics , Izeh fault zone , Saydoon dam sites , Khuzestan Province