银川盆地隐伏断层地球物理探测技术对比分析——以芦花台断裂南段为例

Comparative Analysis of Geophysical Exploration Techniquesfor Hidden Fault in the Yinchuan Basin——Taking the southern section of the Luhuatai Fracture as an example

隐伏断裂尤其是隐伏深大断裂往往与地震及地质灾害紧密相关,而探测隐伏断裂的地球物理方法较多,但对于不同的地质条件,探测效果存在差异.以银川盆地隐伏的芦花台断裂南段为例,通过常规氡气测量、高密度电法、浅层地震勘探法部署综合地球物理手段,分析地球物理探测技术在巨厚第四系覆盖区隐伏断层的探测效果.结果表明,在不能揭穿第四系的情况下,直接采用高密度电法探测的效果不佳;断层上方的氡气放射性浓度明显高于背景值,对断层位置的研究具有指示意义;而小道距、小偏移距、高覆盖次数的浅层地震勘探法,能够较精确地分辨断层空间的展布特征及上断点位置.

Hidden fractures,especially deep fractures,are often closely related to earthquakes and geological hazards.There are many geophysical methods for detecting occult fractures,but the detection effectiveness varies at different geological conditions.Taking the southern section of the insidious Luhuatai Fracture in the Yinchuan Basin as an example,the article deploys integrated geophysical means and explores and comprehensively analyzes detection effect of geophysical sounding techniques on the detection of hidden faults in giant thick quaternary cover areas with conventional radon measurements,high-density electrical methods,and shallow seismic survey methods.The results show that direct high-density electrical detection is ineffective under the condition that the fourth system cannot be uncovered;Radon radioactivity concentrations show significantly higher values above the fault than background,which is of great instruction significance to study the fault location;The shallow seismic prospecting method with mini trace intervals,mini offsets,and high folds has the most obvious detection effect,which can accurately distinguish the spatial spreading characteristics of the fault and the location of upper fault points.