Site effect microzonation of Qom, Iran

As an important step in effectively reducing seismic risk and the vulnerability of the city of Qom to earthquakes, a site effect microzonation study was conducted. Seismic hazard analysis for a return period of 475 years was carried out. Data from 160 borings was collected and analyzed, geophysical surveys were conducted and microtremor measurements taken in more than 60 stations throughout the city. The study area was divided into a grid of 1 × 1 km2 elements and the sub-surface ground conditions were classified into 59 representative geotechnical profiles. Site response analyses were carried out on each representative profile using 30 different base rock input motions. Distribution maps of site periods and peak ground acceleration throughout the city were developed, providing a useful basis for land-use planning in the city.