No abstract

Wuhan East Lake High-tech Development Zone is a National Innovation Demonstration Zone where several major projects are under construction. For the seismic safety evaluation of the zone, it is urgent to find out basic data such as stratigraphic structure, geometric characteristics of buried faults, and overburden thickness. In this study, seismic reflection and microtremor surveys are adopted in seismic safety evaluation in urban areas for the first time. Combined with borehole data, the overburden thickness and buried faults in the target area are detected and analyzed. The results are as follows: ① The seismic reflection detection is carried out for the possible hidden locations of the Xiangfan-Guangji Fault and Macheng-Tuanfeng Fault in the target area, and the obtained high-resolution seismic reflection profiles can be used to precisely divide the stratigraphic structure and preliminarily find out the geometric characteristics such as the strike, tendency, and the buried depth of the upper breakpoint of the buried faults. ② A microtremor survey is carried out in key regions of the target area, and the obtained velocity structure imaging can provide a perspective window into the urban underground space structure and accurately determine overburden thickness and the depth of strongly and moderately weathered bedrock. Comprehensive geophysical measurements can better realize the acquisition of basic data such as the stratigraphic structure of complex regions and characteristics of urban buried faults, which provides an important basis for seismic fortification. At the same time, the combined application of geophysical methods avoids the detection of the blind area and provides a guarantee for urban safety and sustainable development. Furthermore, the study has reference value for seismic safety evaluation in similar areas of the world. If comprehensive geophysical measurement can be popularized, its economic and scientific value will be immeasurable.

The Western Hubei section of the Liangyun fault is an important structural belt of the southern Qinling Mountains thrust nappe system. As the significant activity of the Liangyun fault since the Quaternary has led to high seismic risk in the surrounding area, the research on the characteristics and activity of fault structure is of great significance for deepening the construction of a seismic safety system in this area. In this study, we conducted a field geology survey combined with quartz optical stimulated luminescence dating, scanning electron microscopy dating, and thermoluminescence dating results and comprehensive application of shallow seismic reflection and high-resolution refraction) to analyze the activities of the Liangyun fault in the Quaternary period. Sediment optical stimulated luminescence dating results of samples from the breakpoint were 134.99 + 15.52 and 160.95 + 16.88 ka. Combined with the seismic profile, outcrop observation, and previous dating results, we conclude that the new era is in fault activities in the early Pleistocene to late Pleistocene (Q2–Q3). The combined application of shallow seismic reflection and high-resolution refraction method can confirm each other’s measured results, providing more parameters for the interpretation of seismic data under complex conditions and ensuring the accuracy of data interpretation at the same time. At present, the seismic experiment scheme is less used in the field of active fault detection, since its good detection effect and the application of the trial to shallow geophysical exploration has a certain application value and global scalability.