پديده هاي زمين شناسي مهندسي و ژئوتكنيكي زلزله فروردين 1385 درب آستانه ( سيلاخور )

Preliminary Report of Engineering Geology and Geotechnical Aspects of March 11,2006 Darb-e-Astaneh Earthquake

On 11 March 2006 (04:47 local time, an ML 6.1 earthquake occurred in Silakhor plain in the southeast part of Boroujerd in the Lorestan Province (about 400 km southwest of Tehran). The mainshock claimed 67 lives and injured about 1246 people and caused widespread damage. Strong ground shaking reached a maximum Modified Mercalli intensity of VIII (A. S. Moghadam et al 2006). The Engineering geology and geotechnical aspect of the earthquake includes: liquefaction, landslide, land subsidence and amplification of ground motion by site effect. Extensive liquefactions were seen as sand boiling in 6 places including Laban, Araban, Alak Abad, Karkhaneh Sefidkan, Heydar Abad and Baba Pashman. No evidences from occurring coherent landslides in the earthquake was seen but many active and dormant landslides reactived by the earthquake and blocked the roads in some places. Many disrupted landslides such as rock falls and rock topples occurred during the earthquake. Also, some evidences from amplification of ground motion by site effect were observed. This caused more damage in the farther places from epicenter. During the earthquake land subsidence occurred in two places due to damage in the roof of local Ghanats.