Firouzabad (Kojur) Earthquake of 28 May 2004, Mw6.2, northern Iran: An Engineering Seismological Overview

Category Tectonic & Seismotectonic
Group GSI.IR
Location 23th symposium on geosciences
Holding Date 05 May 2008

      The Firouzabad (Kojur, North Central Alborz of Iran) of 28 may 2004, Mw 6.2, focal depth of 18km, occurred in the east of Chalus highway in the Kojur region. The causative fault was most probably the North-Alborz fault. The macroseismic epicenter of this earthquake was found to be around the Firouzabad village in the south of Kojur valley, where two persons was killed and several adobe building were demolished. The earthquake caused several landslides in a vast region, specially in the Chalus highway, where 27 persons were killed in the cars demolished by the falling rock blocks and debris. The rock falls caused some fires in the cars as well. The preliminary studies show a bilateral directivity effect with an important fault normal component. A maximum acceleration of 0.29g was recorded in a focal distance of 20km. The macroseismic intensity of VIII is estimated for Firouzabad, and the shocks were felt as well in Tehran in a distance of about 70km towards south, with an intensity of VI+. This paper summarizes the results of the field visits and the preliminary processing on the strong motion data.