地震学报（英文版）2004，Vol.17Issue(1)：38-46,9.
Analysis of the 1997 Zirkuh (Ghean-Birjand) aftershock sequence in east-central Iran
Analysis of the 1997 Zirkuh (Ghean-Birjand) aftershock sequence in east-central Iran
摘要
Abstract
In this study, the 1997 Zirkuh (Ghaen-Birjand) locally recorded aftershock sequence was analyzed. On the basis of the distribution of aftershocks, a NW-SE trend vertical faulting with an extension of at least 90 km could be estimated. The fault rupture causing the Zirkuh earthquake apparently initiated in the epicentral area and propagated unilaterally to southeast. The cross-section of aftershocks along the fault suggests that the aftershocks had a depth range of 20 km, indicating that the seismic activity was taking place within the upper crust and the seismogenic layer, in this region, had a thickness not greater than 20 km. The distribution of aftershocks suggested that the western block acted as hanging wall during the source process of the main shock. The time-space distribution of aftershocks showed two distinguished gaps coincided with the observed gaps on the surface faulting. It was concluded that the first gap acted as a barrier during the main shock and aftershocks, while the deeper part of second gap was ruptured either during the main shock or the aftershocks. The time-frequency pattern of aftershocks decay followed the Modified Omori relations for the first 10 days while the Omori model was best fitted for the later stage of the aftershock sequence.关键词
Zirkuh earthquake/seismicity of Khorasan Province/source parameters/focal mechanism/seismotectonics/active faults/aftershock activityKey words
Zirkuh earthquake/seismicity of Khorasan Province/source parameters/focal mechanism/seismotectonics/active faults/aftershock activity分类
天文与地球科学引用本文复制引用
Mohammad-Reza Gheitanchi,Mohammad Raeesi..Analysis of the 1997 Zirkuh (Ghean-Birjand) aftershock sequence in east-central Iran[J].地震学报（英文版）,2004,17(1):38-46,9.基金项目
Research Project from the Institate of Geophysics and Office of the Vice Chancellor for Research of Tehran University (651/1/317) （651/1/317）
