利用主‑被动源法联合探测昆山—嘉定断裂上断点位置

Joint Detection of Upper Breakpoint Location of Kunshan—Jiading Fault Using Active‑passive Source Method

摘要:

为探索深厚覆盖层区城市隐伏断裂探测及其活动性评价，利用主?被动源联合方法对昆山—嘉定断裂进行探测研究。首先采用浅层地震勘探法对昆山—嘉定断裂进行了定位，在断点发育处采用台阵微振动观测技术对覆盖层精细结构探测。验证并更新了昆山—嘉定断裂的断层特征和断裂活动性认识：昆山—嘉定断裂为正断层，倾向为南，倾角约 60°，该断裂错断了新近系、上断点终止于下更新统顶部，上断点埋深约在 220~240 m，投影在地表的坐标为（31.38°N，121.06°E），据此推断昆山—嘉定断裂最新活动时代为第四纪早更新世。主?被动源联合探测法避免了单一勘探方法对隐伏断裂勘探的局限性，可利用主动源法对目标断裂进行初步定位，再利用被动源法确定上断裂位置。主?被动源联合探测法对解决深厚覆盖区隐伏断裂上断点位置具有参考意义。

Abstract:

To explore the detection of urban concealed faults and the evaluation of their activity in deep overburden areas, the Kunshan—Jiading fault was investigated using the joint active-passive source detection method. Firstly, the shallow seismic exploration method was used to locate the Kunshan—Jiading fault, and the fine structure of the overburden layers was detected using array microtremor exploration technology at the breakpoint development zone. The fault characteristics and activity of the Kunshan—Jiading fault were verified and updated: the Kunshan—Jiading fault was a normal fault with a southern inclination and an inclination angle of about 60°. The fault displaced the Neogene strata, with the upper breakpoint terminating at the top of the Lower Pleistocene and buried at a depth of about 220~240 meters. Its projection on the surface was located at coordinates (31.38°N, 121.06°E). Based on this, the latest activity of the Kunshan—Jiading fault was inferred to have occurred during the Early Pleistocene of the Quaternary period. The joint active-passive source detection method overcomes the limitations of a single exploration method for concealed faults. The active source method can be used for preliminary positioning of target faults, followed by the passive source method to determine the location of the upper breakpoint. The joint active-passive source detection method provides a valuable reference for determining the location of the upper breakpoint of concealed faults in deep overburden areas.