关键词: 郯庐断裂带, 板泉盆地, 安丘-莒县断裂, 昌邑-大店断裂, 断层活动性

Abstract: The Anqiu-Juxian fault is the latest active fault in TanLu fault zone, which is also the seismogenic fault of Tancheng M8.5 earthquake in 1668. The shallow seismic reflection profile，laid across the east branch of Anqiu-Juxian fault and the Banchan basin, clearly revealed the stratigraphic interface morphology and shallow fault characteristics. The results show that Banquan Basin, a graben basin developed in the late Quaternary, is composed of multiple faults, and the thickness of Quaternary strata and graben structure characteristics are obviously affected and controlled by faults F1 and F2.Also, the eastern and western sides of the basin are the basement uplift areas, and the Quaternary strata thickness is less than 30m.There are thick Cenozoic strata deposited in the basin, showing the inclined form of shallow west and deep east, which are in unconformity contact with underlying bedrock strata. The east branch of Anqiu-Juxian fault revealed by the shallow seismic reflection profile is composed of two branch faults dipping in opposite direction, which merge into one fault in the deep section. The Banquan section of Anqiu-Juxian fault generally shows a normal fault characteristics of striking NE and dipping W. According to the buried depth of the upper breakpoints of these fractures and the characteristics of the Quaternary activity, Baifenzi-Fulaishan fault on the western boundary of Banquan basin is relatively weak, which is the pre-Quaternary fault. Changyi-Dadian fault on the eastern boundary of Banquan basin and Anqiu-Juxian fault not only dissected the bedrock top interface, but also showed signs of dissecting since Quaternary, and its active age are the late Pleistocene. The research results can provide seismological evidence for further understanding of activity mode and activity age of the seismogenic fault of the 1668 Tancheng M8.5 earthquake, as well as the near-surface characteristics and activity of the Banquan segment of the Tanlu fault zone.

Key words: TanLu fault zone, Banquan basin, Anqiu-Juxian fault, Changyi-Dadian fault, Fault activity.