IGCP 641 Project: Mechanisms, Monitoring and Modeling Earth Fissure Generation and Fault Activation due to Subsurface Fluid Exploitation

pre-existing surface faults) caused by extraction of fluids from the subsurface have been observed in hundreds of sedimentary basins worldwide, mainly in semiarid to arid areas of the USA, Mexico, China, India, Libya, Iran, and Saudi Arabia. Unexpected fissure generation and fault activation associated with anthropogenic land subsidence strongly impacts the development of urban settlements, industrial centers, agricultural and other economic activities. Improved understanding of the geomechanical mechanisms driving the ground failure, accurate monitoring of horizontal and vertical land-surface displacements, and development and application of modelling tools to simulate and predict the temporal and spatial evolution of the processes is needed. An IGCP 641 Project entitled Mechanisms, Monitoring and Modelling Earth Fissure Generation and Fault Activation due to Subsurface Fluid Exploitation (M3EF3), initiated in 2015, proposed a cooperative scientific program between institutions and researchers to improve the understanding of the processes involved in ground rupturing. Land subsidence and ground ruptures accompanying subsurface fluid extraction bear wide implications from a societal point of view, e.g., increasing flood risks, damaging buildings and infrastructures, reducing water availability. Even though major advances in understanding subsidence processes have been achieved, particularly over the several decades (e.g., Poland, 1984; Galloway et al., 1999; Gambolati et al., 2005; Xue et al., 2005), the processes governing ground ruptures remain only partially understood (e.g., how differential vertical compaction, horizontal displacements, variations in the bedrock depth, and (or) activation of pre-existing faults influence near-surface ground failure propagation associated with the surface deformation caused by the over-exploitation of aquifer systems). The occurrence of ground ruptures due to deformation of aquifer systems accompanying groundwater pumping has been observed in many semiarid-to-arid sedimentary basins worldwide. Examples documented in the scientific literature include: Mexico (e.g., Carreón-Freyre et al., 2005, 2010; Pacheco et al., 2006; Carreón-Freyre et al. 2016; Teatini et al. 2018; Ochoa-Gonzalez et al, 2018), southwest USA (e.g., Holzer et al., 1979; Holzer and Galloway, 2005; Conway, 2016), China (e.g., Li et al., 2000; Zhao et al., 2009; Wang et al., 2009; Peng et al. 2016; Zhang et al. 2016; Ye et al. 2018), India (Srivastava, 2009), Iran (Azat and Shaharam, 2010), Saudi Arabia (Bankher and Al-Harthi, 1999), Libya (Rothenburg et al., 1995), and Pakistan (Kakar et al., 2016). In these countries, fracture generation and fault activation have a strong impact on the development of urban settlements, industrial centers, agricultural and other economic activities. The worst incident of ground failure induced by natural-resource exploitation occurred in 1963 in Los Angeles, California, where the dam of the Baldwin Hills Reservoir failed as a result of piping along a fault on which movement had been induced by oil extraction. Flooding caused by the release of 946,000 m of water killed 5 people, destroyed 277 homes and caused many other property damages (Hamilton and Meehan, 1971). Despite this event, ground ruptures caused by the extraction of subsurface fluids has continued during the intervening decades. Important economic, social, and environmental damages have been reported: rupture of borehole casings (Carreón-Freyre et al., 2016), pipes, and canals used for water, oil and gas conveyance, with negative consequences both in rural areas, where the water is mainly used for crop production (e.g., in the Sarir agricultural area, Libyan desert, and in southcentral Arizona in the USA), and in urban areas (e.g., in Mexico City, Querétaro, Morelia, Toluca, Celaya and other cities located within the Transmexican Volcanic Belt in Mexico, in Beijing, Xi’an, Wuxi and other cities in China). Specific consequences include reducing the potable water supply; increasing the cost of groundwater extraction; structural damages to civil structures (e.g., houses, buildings, historical heritage such as palaces and churches); cracking of infrastructures such as streets, rupture of pipelines, railways, and runways; injuries to people, livestock and other animals; creation of preferential flow paths for contaminants from the surface into shallow and deep aquifers; triggering of severe soil erosion and creating badlands topography near the rupture; and degrading ecosystems. Fissure and fracture development has been observed both within the areas where the exploitation of the natural resources occurs and along the boundaries of these areas (Conway, 2016). Density, shape, length, aperture, depth, and dislocation of ruptures vary greatly between areas and are directly related to the subsoil stratigraphic variations. In some places only a few isolated fissures have formed, whereas elsewhere many fissures, IGCP 641 Project: Mechanisms, Monitoring and Modeling Earth Fissure Generation and Fault Activation due to Subsurface Fluid Exploitation