In recent years, the phenomenon of ground fissures emerging in coalfield fire areas has garnered significant scientific attention due to its complex interactions with subterranean heat sources and the destructive potential it holds for both the environment and human infrastructure. A comprehensive review published by Wang, Su, Wu, and colleagues in Environmental Earth Sciences delves into the intricate mechanisms governing the development of these ground fissures and explores how their formation and expansion actively exacerbate the spread of underground coal fires. This groundbreaking synthesis underscores the mutually reinforcing feedback loop between geological instability and combustion dynamics, revealing a multifaceted process with profound ecological and economic implications.
At the heart of the coalfield fire problem lies the spontaneous ignition of coal seams, often buried deeply beneath layers of overburden. These subterranean fires can smolder undetected for years, generating extreme heat and toxic emissions. The reviewed work elucidates how the thermal regime established by such fires significantly weakens and alters the mechanical properties of the surrounding strata. Elevated temperatures induce desiccation and thermal degradation of the host rocks, resulting in differential expansion and contraction that initiates tensile stress fields within the overlying ground layers. Such stresses gradually culminate in the inception of fissures—fractures that breach to the Earth’s surface.
The development of these fissures is far from a passive consequence of heat. Instead, the authors highlight their active role in facilitating the ingress of atmospheric oxygen into the subsurface. As fresh air penetrates through these cracks, it supplies vital oxygen that intensifies combustion rates within the coal seams. This cycle perpetuates itself; as fires burn hotter and consume coal more rapidly, thermal stresses increase, further expanding existing fissures or spawning new ones. The result is a self-reinforcing feedback loop that accelerates both ground instability and coal fire propagation.
A key facet emphasized in the analysis is the heterogeneity of geological formations and how variable lithology influences fissure morphology and spread. Coal-bearing strata interbedded with clastic sediments such as sandstones, shales, or mudstones display differing thermal conductivities and mechanical strengths. These variances govern how heat diffuses through the strata and where stresses localize, leading to fissures of varying sizes, depths, and orientations. Understanding these geological controls allows for more precise prediction and monitoring of fissure-prone regions in active coalfield fire zones.
Beyond the geomechanical processes, the review draws attention to the role of hydrogeology in fissure development. The presence of groundwater and its movement—either naturally or induced by mining activities—can significantly impact fissure formation. Evaporation and vaporization driven by subsurface heat can generate steam pressures that contribute to rock fracturing. Additionally, changes in pore water pressure may destabilize strata, facilitating fissure propagation. The interaction between thermal, mechanical, and hydrological forces presents a complex system that requires integrated, multidisciplinary study to decipher.
From an ecological perspective, the consequences of ground fissures in coal-bearing terrains are profound and multifaceted. The openings serve as vents for the release of hazardous gases such as carbon monoxide, methane, and volatile organic compounds, profoundly degrading air quality and posing health risks to nearby communities. Moreover, surface fissures destabilize soils, increasing susceptibility to erosion and altering natural drainage patterns. These perturbations can decimate local vegetation and disrupt ecosystems, underscoring the urgency for effective management strategies.
Technological advances in remote sensing and geophysical surveying have revolutionized fissure detection and coal fire monitoring. Thermal infrared imaging allows detection of anomalous surface heat signatures indicative of active combustion zones, while ground-penetrating radar and seismic techniques can delineate subsurface fractures. The reviewed paper argues for integrating these methods with in situ observations and numerical modeling to build comprehensive spatial-temporal understanding. Such integrated approaches enable early warning systems that could mitigate damage by informing timely intervention measures.
The authors also explore the anthropogenic dimension of this phenomenon, especially how mining practices inadvertently promote fissure formation and coal fire spread. Subsurface excavation alters stress fields and depletes overburden support, creating pathways for oxygen influx and enhancing heat exchange. Abandoned or improperly sealed mine entries act as conduits for airflow, while surface subsidence resulting from extraction can initiate fissures. Therefore, mining design and reclamation protocols must incorporate understanding of fissure dynamics to curtail the genesis and exacerbation of coal fires.
From a theoretical modeling standpoint, the paper reviews various mechanical and thermal simulation frameworks employed to replicate the fissure-fire feedback system. Coupled thermo-mechanical models simulate stress accumulation and fracturing under evolving temperature fields. Gas flow models forecast oxygen transport and combustion kinetics within fissured strata. However, the authors note limitations in capturing the full complexity of field observations, calling for enhanced model parameterization grounded in empirical data. Advances in computational power and machine learning techniques offer promising pathways to bridge this gap.
The potential economic damages stemming from this interconnected process are substantial. Infrastructure collapse due to ground instability threatens transportation routes, buildings, and mines themselves. Moreover, coal fires consume valuable mineral resources, leading to loss of mining revenue and escalating remediation costs. Governments and industries are thus compelled to invest in monitoring and control technologies informed by rigorous scientific understanding, such as that synthesized in this review.
In terms of mitigation, the paper discusses strategies aimed at disrupting the reinforcing cycle between fissures and fire spread. Surface sealing of fissures to limit oxygen access, heat extraction methods, inert gas injections, and controlled flooding form part of the arsenal against coalfield fires. Nevertheless, implementation challenges persist, particularly in vast or remote coalfields. Optimal intervention designs depend on detailed assessments of fissure networks, fire intensity, and local geological conditions.
Environmental policy implications stemming from these findings are significant. Regional planning must consider the inherent risks posed by ongoing coalfield fires and associated fissures to safeguard public health and safety. The review advocates for multidisciplinary cooperation among geologists, engineers, ecologists, and policymakers to develop integrated response frameworks. Public awareness campaigns are also vital to communicate hazards and mobilize community engagement.
Looking ahead, the authors identify critical knowledge gaps, such as the need for enhanced characterization of micro-scale fracture initiation under thermal stress, and quantification of gas exchange dynamics through fissures. They emphasize the benefit of longitudinal studies that track fissure evolution and fire behavior over time, combined with pilot-scale experiments that validate theoretical models. Such research endeavors will be pivotal in advancing both fundamental understanding and practical solutions.
In sum, this exhaustive review sheds light on the synergistic mechanisms by which ground fissures develop in coalfield fire areas and, in turn, facilitate the propagation of subsurface coal combustion. The feedback loop they form is central to the escalating severity of coal fires witnessed globally, posing a challenge that blends geological complexity with environmental urgency. By exposing these interdependencies, the study equips stakeholders with critical insights necessary to innovate monitoring, prevention, and remediation strategies, potentially mitigating one of the most intractable environmental hazards of the industrial age.
Subject of Research: Mechanism of ground fissure development in coalfield fire areas and its impact on the spread of coal fires
Article Title: A Review: Mechanism of ground fissure development in coalfield fire areas and its mutually reinforcing on the spread of coal fire
Article References:
Wang, Y., Su, H., Wu, W. et al. A Review: Mechanism of ground fissure development in coalfield fire areas and its mutually reinforcing on the spread of coal fire. Environ Earth Sci 84, 343 (2025). https://doi.org/10.1007/s12665-025-12294-1
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