Preliminary Seismic Site Classification Map of Sarpol-e Zahab

The destructive earthquake of Sarpol-e Zahab (Mw=۷.۳, Depth=۱۸ Km) lead to sever damages to manyof structures of the affected region. The first reconnaissance of the area showed that the structures damage distribution could be interpreted by the effect of local site conditions. Therefore, some microtremor measurements and geophysical surveys were performed to investigate this concern. The survey included totally ۴۱ locations of microtremor measurements and ۴۰ locations of geophysical refraction profiles, the distribution of which covered all over the city. The recorded motions were analyzed using horizontal to vertical spectral ratio (HVSR) method to determine the natural frequencies of the alluvium; primary and secondary waves velocitywere also measured as a complementarydata. The survey results concluded to the preliminary seismic site classification map for the city, which would be useful for future safe design of structures.

Keywords:

Seismic site classification , Geophysical surveys , Microtremor measurements