## 1 Introduction  
Since the Ministry of Natural Resources of the People's Republic of China issued \"Notice on strengthening urban geological survey\" in 2017 [1], a series of urban geological survey work was deployed by the Ministry of Natural Resources and China Geological Survey at the national level as well as the Department of Natural Resources and the geological industry management department at the provincial level. The Ministry of Natural Resources issued the code for urban geological investigation [2] at the end of 2017, the contents involving the geophysical exploration work mainly are as follows: (1) exploration of basic geological conditions in cities; (2) survey and evaluation on urban natural resources; (3) survey and evaluation on the urban geological environment; and (4) urban geological disaster investigation. Urban geological survey is the predecessor activity of urban development as well as being the basis of urban space's effective and comprehensive utilization. Since the survey of territorial resources in 1999 [3], urban geological work is getting more and more conclusions, and presents a rapid development trend. Environmental geology survey and evaluation of major cities (group) in China have been accomplished, led by the Ministry of Natural Resources and the China Geological Survey. Three-dimensional urban geological surveys were carried out and the underground three-dimensional structure of the city was established. A three-dimensional visualization urban geological information management decision platform and a public-facing urban geological information service system were also established. From 2004 to 2012 [3], the Ministry of Natural Resources and the China Geological Survey completed environmental geological surveys in major cities all over the country. The investigation preliminarily identified different kinds of urban environmental geological problems including landslide, collapse, debris flow, land subsidence, soil and water pollution, active faults, mine geological environment problems, and the state of geological resources such as groundwater, geothermal, mineral water, and geological landscape was clarified. Since 2009 [3], under the unified deployment of the Ministry of Land and Resources, the multi-party cooperation mode of ministry, province, and city has been adopted to carry out urban geological surveys of 28 cities, including Fuzhou, Xiamen, Quanzhou, Suzhou, Zhenjiang, Jiaxing, Hefei, Shijiazhuang, Tangshan, Qinhuangdao, and Jinan among their number. Since 2010 [3], in order to serve the needs of the national regional strategy and main function zoning, comprehensive geological surveys have been carried out in key urban agglomerations such as Beijing-Tianjin-Hebei, Yangtze River Delta, Pearl River Delta, the west coast of Taiwan Strait, Beibu Gulf, middle reaches of Yangtze River, Guanzhong, Central Plains, and Chengdu-Chongqing. Hunan province has also cooperated with the Ministry of Natural Resources in recent years; since July 2008 [3], the Hunan Provincial Institute of Geological Survey has undertaken a comprehensive survey and regionalization of the geological environment of the Changsha-Zhuzhou-Xiangtan Urban agglomeration, hydraulic and environmental geological survey of Changsha-Zhuzhou-Xiangtan Urban agglomeration and other projects. At present, Changde city geological environment survey, Yiyang city geological environment survey and Yueyang city geological survey projects are in progress. With the deepening of urban geological survey in recent years, geophysical exploration technology has also made some scientific and technological achievements. As early as 1993, [PERSON] et al. [4] used an electric method, a magnetic method, the creation of an artificial earthquake and other methods to conduct multi-method detection tests on the large area of ground fissure and collapse in Changjiang Road, Tongling City, the results indicating that shallow seismic exploration was the most effective method.