Risk assessment and spatial regulation on urban ground collapse based on geo-detector: a case study of Hangzhou urban area

China’s large- and medium-sized cities have entered the stage of seeking space resources underground. The safety of underground spaces has become an important issue for the high-quality development of cities. Urban ground collapse (UGC) is a common accident that occurs in underground spaces and is affected by a combination of factors. In this study, Internet news was used to supplement the data of the relevant departments, and a database of 68 UGC events from 1964 to the present was built. The probability distribution of the UGC risk was calculated using the nearest neighbor and density models. Then, the geo-detector was used to explore the explanatory power of risk factors, including natural environmental and socio-economic factors. The results show that the impact of the explanatory power of risk factors on UGC, from high to low, is population density, metro influence, and soil type. The interaction of factors enhances the explanatory power, whereby the interaction between socio-economic and natural environmental factors represented by population density and soil type is the highest. A risk division map of UGC in Hangzhou was obtained, with proportions of type I (0.6%), type II (28.3%), and type III (71.0%) areas. This study demonstrates the influence of human activities on UGC events through quantitative results and provides research support for urban underground safety risk assessment.