Ground fissure is a form of geological disaster caused by externally and internally geological complex interactions in soil masses (Rogers, 1967; Hauksson, 1983; Baruni, 1994; William et al., 1995; David et al., 2001; Wang et al., 2008; Wang et al., 2019a, 2019b). Houses, crops, roads, and other infrastructure are frequently damaged (William et al., 1995; Sarkar, 2004; Peng et al., 2016; Wang et al., 2019a; Jia et al., 2021).
Within tensional fault basins and rift valleys, the tectonic activity, and human behavior are often very strong, for example, fault creep, seismic activity, pumping, and irrigation, which have caused the outcropping and expansion of many earth fissures (Deng et al., 1994; Peng et al., 2016; Wang et al., 2020a). Domestic and foreign experts have studied the ground fissures in these areas more extensively and intensively (Pratt, 1998; Li et al., 2000; David et al., 2001; Peng et al., 2016; Pacheco-Martínez et al., 2013). The majority of the fissures in basins are tectonic fissures. Their formation and development are inextricably linked to fault activity (Wang et al., 2020a). At the beginning of the research on ground fissures, fault-controlled ground fissures were often considered a precursor of earthquakes, and thus many studies were focused on the effects of earthquakes on ground rupture (Brian, 1998). Leonard, R.J. studied a fissure in the Picacho Basin, Arizona, USA, which was the first tectonic ground fissure to be explored and published in the literature by scholars. He believed the fissure was probably the result of vibrations from a distant earthquake (Leonard, 1929). Fault viscous slip can cause a sudden release of energy, which is transmitted to the loose sediment layer near the surface in the form of seismic waves, thus causing the soil to rupture and expand to form ground fissures (Pratt, 1998; Alan et al., 2003; Sarkar, 2004; Reclaimed Land Geological Research Group, 2016; Yao et al., 2019). After years of investigation and exploration, numerous studies have confirmed that most of the ground fissures associated with fault activity are due to slow creep slip (Earl et al., 1988; David et al., 2001; Wang et al., 2020). The production and growth of ground fissures are accelerated by the actions of underlying faults, resulting in a fracture system in the surface strata (Wang et al., 2020a).
However, an examination of the monitoring data indicated that the ground fissure's vertical activity rate is substantially higher than that of the underlying fault, indicating that fault activity is not the main cause of the production of ground fissures (Wang et al., 2019a). The growth and outcropping of earth fissures are influenced by pumping action (Pacheco et al., 2006; Muniram, 2011). Both fault activity and pumping activity are important factors in the formation of ground fissures. Fault activity acts in the deep part of the formation while pumping activity acts in the interior of the loose layer and makes the activity rate of ground fissures significantly greater than that of the underlying faults (Robert et al., 1979; Li et al., 2000; Budhu et al., 2012; Pacheco-Martínez et al., 2013; Wang et al., 2019a; Jia et al., 2021). Groundwater extraction can cause differential settlement in the hanging and heading walls of the fissure, which contributes to the rupture and expansion of the fissure (Wang et al., 2020b). The magnitude of this differential settlement is related to the amount of water pumped, the duration of pumping, and the location of the pumped layer, and is also closely related to the thickness and form of the aquifer (Muniram, 2011; Wang et al., 2019a; Jia et al., 2021).
With about 46 km in length and an 80–120 m impact bandwidth, the Jiaocheng ground fissure is one of the longest fissures found in the world (Peng et al., 2020a). Many scholars point out that this fracture is closely related to the Jiaocheng fault, and that groundwater mining has intensified the fracturing activity (Liu et al., 2018; Peng et al., 2020b). However, the characteristics and mechanisms of the Jiaocheng ground fissures need to be systematically summarized and analyzed. This study highlights several difficult challenges in the longest fissure, encouraging more research into fissure mechanisms and offering useful information for fissure prevention.