松原市扶余北隐伏活动断裂地震潜势研究

扶余肇东断裂带是松辽盆地中一条重要的隐伏发震断裂带,2006年和2014年在此断裂带上发生了多次近6级地震,地震活动主要集中在断裂的东北段和查干花段。在2012—2014年的松原市活断层探测工作中,探明扶余肇东断裂带东北段经过松原市区,该段呈近EW向,具有明显的分段性和独立性,将其命名为扶余北断裂。通过三维物探资料和浅层人工探测,确定了扶余北断裂的空间展布和剖面特征,并利用联排钻孔探测和光释光测年技术,确定该断裂存在晚更新世以来的活动;利用石油物探资料获得的基岩面破裂规模,对扶余北断裂的地震潜势进行了估计,并进行了概率性地震危险性研究。

Seismic Potential Research along the North Fuyu Fault in Songyuan City

The Fuyu-Zhaodong Fault is an important buried seismogenic fault in the Songliao Basin.In 1119A.D.an M_S6.75 earthquake occurred on the fault,the largest ever recorded before the Haicheng earthquake of Northeast China in 1975.In 2006 and 2014 several earthquakes below MS6.0 occurred along the fault; these recent earthquakes were mainly centralized on the northeast segment and the Chaganhua segment.Active faults were detected in Songyuan city from 2012 to 2014 and the northeast segment of the Fuyu-Zhaodong Fault was proven to cross downtown with a near-EW trend and showed obvious segmentation and independence.The urgency and importance of meticulous detection of the fault is obvious for this urban environment.Using three-dimensional geophysical data from oilfield and shallow geophysical prospecting,the space distribution and profile characteristics of this fault (named the north Fuyu Fault) were determined.The combined methods of borehole detection and optical stimulated luminescence dating were also used to confirm the seismicity along the fault since late Pleistocene.Using the rupture scale of bedrock surface from the three-dimensional geophysical data,this paper estimates the seismic potential along the north Fuyu Fault and studies its probabilistic seismic risk using a probabilistic calculation method.A Poisson probability model is adopted and quantitative parameters,such as maximum magnitude,recurrence period,and occurrence probability in the coming 50~200 years,are calculated.This presents a breakthrough in the study of potential seismogenic faults that have few historical earthquake records and long return periods.