University of Tehran Press Journal of the Earth and Space Physics 2538-371X 24 1 1998 03 21 - - 13090 FA Journal Article 1970 01 01 The Feb. 4, 1997 Bojnourd earthquake of M 6.8 occurred in a mountainous area, North-East Iran, and caused extensive destruction. Relatively a fewer human lives were lost due to a strong foreshock. Field investigation and aftershocks distribution suggest a NW-SE faulting with a right-lateral strike-slip motion. Aftershock activity was scattered indicating that the mainshock activated the nearby minor faults. Aftershocks extended to a length of 45km and a depth of 20km. The average stress drop was estimated to be 20 bar and the static displacement was 35 em. Great destruction in the affected area was mainly caused by poor seismic resistance of traditional adobe houses. Well designed buildings in the epicentral region survived with minor damage. The ground-motion characteristics during the mainshock should be considered for the high safety design of structures in the damaged area. The Feb. 4, 1997 Bojnourd earthquake of M 6.8 occurred in a mountainous area, North-East Iran, and caused extensive destruction. Relatively a fewer human lives were lost due to a strong foreshock. Field investigation and aftershocks distribution suggest a NW-SE faulting with a right-lateral strike-slip motion. Aftershock activity was scattered indicating that the mainshock activated the nearby minor faults. Aftershocks extended to a length of 45km and a depth of 20km. The average stress drop was estimated to be 20 bar and the static displacement was 35 em. Great destruction in the affected area was mainly caused by poor seismic resistance of traditional adobe houses. Well designed buildings in the epicentral region survived with minor damage. The ground-motion characteristics during the mainshock should be considered for the high safety design of structures in the damaged area. https://jesphys.ut.ac.ir/article_13090_da7556f2203ad933e47946017a439b81.pdf