Evidence for Holocene activity of the Yilan-Yitong fault, northeastern section of the Tan-Lu fault zone in Northeast China

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• 作者：Wei Min^a ; ^{dzs_min@yahoo.com.cn} ; Yugang Liu^a ; ^{csbiglyg@sina.com} ; Decheng Jiao^b ; ^{dechjiao@sohu.com} ; Jian Shen^c ; ^{sj2984@sina.com} ; Xiaolong Pan^c ; ^{panxd1970@126.com}
• 关键词：Tan-Lu fault zone ; Yilan-Yitong fault ; Fault scarp ; Holocene activity
• 刊名：Journal of Asian Earth Sciences
• 出版年：2013
• 出版时间：May, 2013
• 年：2013
• 卷：67-68
• 期：Complete
• 页码：207-216
• 全文大小：4149 K

文摘

The Tan-Lu fault zone (TLFZ) is the largest of the major faults in eastern China. Many strong earthquakes have occurred on its section in North China, but no quake greater than M ? 6 has been documented in history at its northeastern section, the Yilan-Yitong fault (YYF) in Northeast China. It is usually considered that this fault has been inactive since late Quaternary and incapable of generating moderate-sized quakes. This conclusion is, however, questioned by our recent work based on high-resolution satellite image interpretation and field investigation. We found a 70-km-long surface scarp near Fangzheng county in Heilongjiang province (HLJP) and a 20-km-long scarp near Shulan county in Jilin province (JLP), and both are associated with the YYF. The trenches across these two scarps reveal a ¹⁴C displacement date of 1730 ¡À 40 years BP at Fangzheng and of 4410 ¡À 30 years BP at Shulan. The dextral offsets of the Songhua River and Second Songhua River and nearly horizontal fault striations indicate that the new activity of the YYF has been dominated by dextral strike slipping with a normal component. These new data suggest that, at least for partial sections, the YYF has been active since the Holocene, implying a potential seismic hazard. However, current quake-protection standards in this region are very low due to the previous view that the YYF fault has not been active since the late Quaternary. If an M ? 7 quake takes place on this fault, it will be a devastating event. Therefore, it is necessary to conduct a detailed study on the whole YYF and to reassess its future seismic risk.