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Unusual cases of mining subsidence from Great Britain, Germany and Colombia

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Abstract

Subsidence involves sinking of the ground surface. The movement generally is localised and may or may not involve some amount of horizontal movement. It may be rapid or take place gradually over a period of time. Subsidence may be brought about by natural causes as, for example, when the roof of a cavern in limestone is weakened to the extent that it is no longer self-supporting and so collapses. Other more exotic examples are associated with volcanism and earthquakes. Perhaps, however, subsidence is more frequently associated with movements caused by mining activities, that is, the removal of mineral deposits, be they in solid, liquid or gaseous form, from within the ground. Mining is one of the earliest activities of man and has taken place in every continent. Subsidence also can result from subsurface excavations such as tunnels, caverns, cellars and sewers. One of the added problems of some forms of subsidence is that it is impossible to predict. This, coupled with the fact that the presence of potentially collapsible voids may be unknown, unrecorded or simply forgotten about further complicates the problem. The objectives of this paper are to document and draw attention to a number of unusual examples of subsidence. These have been generated due to the mining of chalk in southern England, the collapse of slate mines and caverns in Germany, the underground extraction of evaporites in Northern Ireland, fault reactivation in Wales and northern England and the extensive extraction of pumice on the flanks of Galeras volcano in Colombia.
... Geological events related to land instability (mass movements, rock falls, and subsidence) are natural phenomena conditioned, fundamentally, by soil and rock properties, topography, rainfall, and vegetation [1][2][3][4][5][6]. In general, instabilities have caused significant damage to civil infrastructure with significant economic losses [7][8][9][10][11]. However, the most notable thing is that these phenomena put people's lives at risk [5,12] and cause irreversible environmental damage [8,9,13]. ...
... In general, instabilities have caused significant damage to civil infrastructure with significant economic losses [7][8][9][10][11]. However, the most notable thing is that these phenomena put people's lives at risk [5,12] and cause irreversible environmental damage [8,9,13]. ...
... In uncontrolled mines or without the due technical considerations, adverse effects can be caused in environmental aspects and ground instability [16][17][18][19]. Subsidence is a frequent geological problem in extractive activities of solid resources [9,13,[20][21][22][23][24][25][26][27][28][29][30][31] and liquid resources [10,32,33]. If mining operations are developed in urban environments, it is necessary to carry out geological-geotechnical studies to establish this safety initiative. ...
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In the last decade, in the mining district of Zaruma-Portovelo, there has been significant land subsidence related to uncontrolled mining activity. The purpose of this work was to carry out a surface and underground geomechanical characterization of a mining sector north of the city of Zaruma that allows the definition of potentially unstable areas susceptible to the mass movement. The methodology used consists of the following stages: (i) compilation of previous studies; (ii) surface and underground characterization of rocky material to establish its susceptibility to mass movement; (iii) interpretation of results; and (iv) proposal of action measures. Among the most relevant results, it stands out that 26.1% of the 23 stations characterized on the surface present conditions that vary from potentially unstable to unstable. In underground galleries, the studied mean values of the 17 stations indicate that the rock has a medium to good quality, representing a medium susceptibility to gallery destabilization. The results obtained for the surface areas (depths up to 50 m, where altered materials predominate) and the underground areas (depths > 50 m, where the alterations are specific) can be used to identify the areas with a more significant potential for instability. For both cases, it has been possible to define specific monitoring, control, and planning actions for sensitive areas.
... In the case of mining, the heterogeneous rock mass with geological discontinuities affects stress redistribution. Therefore, the ground subsidence can be influenced [5,93,94]. In addition, there have been no earthquakes in Laizhou City since 2018 according to the earthquake data. ...
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Ground subsidence is a common geological phenomenon occurring in mining areas. As an important Chinese gold mine, Sanshandao Gold Mine has a mining history of 25 years, with remarkable ground subsidence deformation. Mining development, life security, property security and ecological protection all require comprehension of the ground subsidence characteristics and evolution in the mining area. In this study, the mining subsidence phenomenon of the Sanshandao Gold Mine was investigated and analyzed based on Persistent Scatterer Interferometry (PSI) and small baseline subset (SBAS). The SAR (synthetic aperture radar) images covering the study area were acquired by the Sentinel-1A satellite between 2018 and 2021; 54 images (between 22 February 2018 and 25 May 2021) were processed using the PSI technique and 24 images (between 11 April 2018 and 12 July 2021) were processed using the SBAS technique. In addition, GACOS (generic atmospheric correction online service) data were adopted to eliminate the atmospheric error in both kinds of data processing. The interferometric synthetic aperture radar (InSAR) results showed a basically consistent subsidence area and a similar subsidence pattern. Both InSAR results indicated that the maximum LOS (line of sight) subsidence velocity is about 49 mm/year. The main subsidence zone is situated in the main mining area, extending in the northwest and southeast directions. According to the subsidence displacement of several representative sites in the mining area, we found that the PSI result has a higher subsidence displacement value compared to the SBAS result. Mining activities were accompanied by ground subsidence in the mining area: the ground subsidence phenomenon is exacerbated by the increasing mining quantity. Temporally, the mining subsidence lags behind the increase in mining quantity by about three months. In summary, the mining area has varying degrees of ground subsidence, monitored by two reliable time-series InSAR techniques. Further study of the subsidence mechanism is necessary to forecast ground subsidence and instruct mining activities.
... Furthermore, several studies have also focused on ground movement associated with fault activation. Bell et al. (2005) reported mining subsidence from Great Britain, Germany and Colombia, and stated that mining area experiencing reactivation of faults should be surveyed properly before construction and a safe gap of at least 10 m should be maintained between the fault zone's edge and any structures. Moreover, Mohammady et al. (2019) employed Random Forest theory to analyse subsidence susceptibility and found that gap from the fault, elevation, slope angle and water table had the largest influence on ground deformation. ...
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Underground coal mining activities and ground movement are directly correlated, and coal mining-induced ground movement can cause damage to property and resources, thus its monitoring is essential for the safety and economics of a city. Fangezhuang coal mine is one of the largest coalfields in operation in Tangshan, China. The enormous amount of coal extraction has resulted in significant ground movement over the years. These phenomena have produced severe damages to the local infrastructure. This paper uses the finite difference method (FDM) 3D model and the stacking interferometric synthetic aperture radar (InSAR) method to monitor the ground movement in Fangezhuang coalfield during 2016. The FDM 3D model used calibrated Fangezhuang geological parameters and the satellite InSAR analysis involved the use of ascending C-band Sentinel-1A interferometric wide (IW) data for 2016. The results show that the most prominent subsidence signal occurs in mining panel 2553N and the area between panel 2553N and fault F0 with subsidence up to 57 cm. The subsidence observed for the FDM 3D model and stacking InSAR to monitor land deformation under the influence of fault are in close agreement and were verified using a two-sample t -test. It was observed that the maximum subsidence point shifted towards the fault location from the centre of the mining panel. The tectonic fault F0 was found to be reactivated by the coal mining and controls the spatial extent of the observed ground movement. The impact of dominant geological faults on local subsidence boundaries is investigated in details. It is concluded that ground movement in the study area was mainly induced by mining activities, with its spatial pattern being controlled by geological faults. These results highlight that the two methods are capable of measuring mining induced ground movement in fault dominated areas. The study will improve the understanding of subsidence control, and aid in developing preventive measures in Fangezhuang coalfield with fault reactivation.
... Among the mentioned calculation methods, Knothe theory [5] is the method that has been widely used for over 60 years. It is used in forecast calculations of surface movements that are caused by mining operations, not only in Poland [13][14][15][16][17][18] but also in many other countries; these include Germany [19][20][21][22][23], the Czech Republic [24][25][26], China [27][28][29][30][31], the USA [32][33][34] and other regions [35][36][37][38][39]. ...
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This paper presents a method for determining the standard deviation and variation coefficient for both the predicted and measured values of horizontal strain that were caused by underground mining operations. The solution was based on a discrete model of the rock–soil medium response to the effects of mining operations. The “elementary horizontal strain increment” variable was random and could be described using the normal distribution. It was also assumed that the average horizontal strain values could be described using the solution given by Budryk and Knothe. The obtained solution allows for a much more comprehensive analysis of the results of deformation forecasts that are obtained with a view toward the protection of buildings that are located on the surface.
... Mining and subsidence are closely connected, no matter the form of the deposit. Some examples include chalk mining in southern England, collapse of slate mines and caverns in Germany, underground extraction of evaporites in Northern Ireland, fault reactivation in Wales and northern England, and extensive extraction of pumice on the flanks of Galeras volcano in Colombia (Bell et al., 2005). In Hungary, hydrocarbon extraction caused a depression with a maximum depth of 40 m in the vicinity of Debrecen (Sütő, 2010). ...
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Mining is of interest to geomorphologists because of the unique types of excavated and accumulated landforms and landscapes that are vulnerable to geomorphic hazards. Mining is extensive worldwide. It produces more sediment than paved road construction, house construction or agriculture. Mining is associated with increasing vulnerability to slope failures, erosion, floods, sedimentation, subsidence, and other geomorphic hazards. Understanding and effectively applying geomorphic principles are important for preventing or minimizing the negative effects of mining. This chapter discusses the types and history of mining operations and associated geomorphic impacts that may result in characteristic landforms and landscapes. It then describes mining-related geomorphic hazards and the nascent fields of sustainable mining and mined-land reclamation. We have much still to learn from the study of mining landscapes, with potential applications in landscape evolution, models of geomorphic hazards, reclamation, and Quaternary geology and geomorphology. Given a growing global population and expanding demands for mineral resources, the need for sustainable practices will increase and wise application of geomorphic knowledge in mined landscapes will become increasingly important.
... Ground subsidence is a global geohazard phenomenon that involves gradual downward settling or sudden sinking of the Earth's surface at a regional or local scale (Bell et al., 2005). Both natural processes (e.g. ...
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Owing to the disastrous consequences of ground subsidence in the urban area, great attention had always been accorded to areas with suspected signs of subsidence occurrence in order to mitigate its effect. Microgravity and electrical resistivity imaging (ERI) survey techniques were conducted at a parking lot of which possible occurrence of subsidence is anticipated due to the increased exposure of surface cracks and very slight depression. This study aimed to map and delineate the subsurface condition of the area with the view of revealing probable subsidence prone zones within the study area. To this end, the microgravity survey data was acquired at a station interval of 2 m. Pole-dipole configuration with 2 m electrode separation was adopted for the electrical resistivity imaging survey. The two methods showed good correlation with each other and proved their effectiveness in imaging the subsurface. A large proportion of the subsurface area was found to be residual soil (mainly silt and or clayey sand) with saturated zones identified by low gravity (<-40.94 mGal) and resistivity (<150 Ω.m) values, which have the tendency to undergo expansion and contraction processes due to rise and fall in moisture content. The subsurface condition was found to be relatively stable, devoid of any subsidence triggering features such as voids or cavities. However, it is inferred to be unsuitable for engineering structures due to the expansive and contractive properties of the subsurface geomaterials (residual soil). Therefore, it is concluded that the area is not prone to subsidence and the surface cracks presents are mere effects of the expansion and contraction process, which could be avoided by the excavation of the expansive soil or good engineering design before the establishment of any structure.
... Ground subsidence is a global geohazard phenomenon that involves gradual downward settling or sudden sinking of the Earth's surface at a regional or local scale (Bell et al., 2005). Both natural processes (e.g. ...
Article
Full-text available
Owing to the disastrous consequences of ground subsidence in the urban area, great attention had always been accorded to areas with suspected signs of subsidence occurrence in order to mitigate its effect. Microgravity and electrical resistivity imaging (ERI) survey techniques were conducted at a parking lot of which possible occurrence of subsidence is anticipated due to the increased exposure of surface cracks and very slight depression. This study aimed to map and delineate the subsurface condition of the area with the view of revealing probable subsidence prone zones within the study area. To this end, the microgravity survey data was acquired at a station interval of 2 m. Pole-dipole configuration with 2 m electrode separation was adopted for the electrical resistivity imaging survey. The two methods showed good correlation with each other and proved their effectiveness in imaging the subsurface. A large proportion of the subsurface area was found to be residual soil (mainly silt and or clayey sand) with saturated zones identified by low gravity (<-40.94 mGal) and resistivity (<150 Ω.m) values, which have the tendency to undergo expansion and contraction processes due to rise and fall in moisture content. The subsurface condition was found to be relatively stable, devoid of any subsidence triggering features such as voids or cavities. However, it is inferred to be unsuitable for engineering structures due to the expansive and contractive properties of the subsurface geomaterials (residual soil). Therefore, it is concluded that the area is not prone to subsidence and the surface cracks presents are mere effects of the expansion and contraction process, which could be avoided by the excavation of the expansive soil or good engineering design before the establishment of any structure.
... Ground subsidence is a global geohazard phenomenon that involves gradual downward settling or sudden sinking of the Earth's surface at a regional or local scale (Bell et al., 2005). Both natural processes (e.g. ...
Article
Full-text available
Owing to the disastrous consequences of ground subsidence in the urban area, great attention had always been accorded to areas with suspected signs of subsidence occurrence in order to mitigate its effect. Microgravity and electrical resistivity imaging (ERI) survey techniques were conducted at a parking lot of which possible occurrence of subsidence is anticipated due to the increased exposure of surface cracks and very slight depression. This study aimed to map and delineate the subsurface condition of the area with the view of revealing probable subsidence prone zones within the study area. To this end, the microgravity survey data was acquired at a station interval of 2 m. Pole-dipole configuration with 2 m electrode separation was adopted for the electrical resistivity imaging survey. The two methods showed good correlation with each other and proved their effectiveness in imaging the subsurface. A large proportion of the subsurface area was found to be residual soil (mainly silt and or clayey sand) with saturated zones identified by low gravity (<-40.94 mGal) and resistivity (<150 Ω.m) values, which have the tendency to undergo expansion and contraction processes due to rise and fall in moisture content. The subsurface condition was found to be relatively stable, devoid of any subsidence triggering features such as voids or cavities. However, it is inferred to be unsuitable for engineering structures due to the expansive and contractive properties of the subsurface geomaterials (residual soil). Therefore, it is concluded that the area is not prone to subsidence and the surface cracks presents are mere effects of the expansion and contraction process, which could be avoided by the excavation of the expansive soil or good engineering design before the establishment of any structure.
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In this study, we focus on improved constraint of the glacial isostatic adjustment (GIA) signal at present-day, and its role as a contributor to present-day sea-level budgets. The main study area extends from the coastal regions of northwestern Europe to northern Europe. Both Holocene relative sea level (RSL) data as well as vertical land motion (VLM) data are incorporated as constraints in a semi-empirical GIA model. 71 geological rates of GIA-driven RSL change are inferred from Holocene proxy data and 108 rates of vertical land motion from GNSS provide an additional measure of regional GIA deformation. Within the study area, the geological RSL data complement the spatial gaps of the VLM data and vice versa. Both datasets are inverted in a semi-empirical GIA model to yield updated estimates of regional present-day GIA deformations. A regional validation using tide gauges is presented for the North Sea, where the GIA signal may be complicated by lateral variations in Earth structure and existing predictions of regional and global GIA models show discrepancies. The model validation in the North Sea region suggests that geological data are needed to fit independent estimates of GIA-related RSL change inferred from tide gauge rates, indicating that geological rates from Holocene data do provide an important additional constraint for data-driven approaches to GIA estimation.
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The problem of the ground collapses is common for the regions affected by the underground mining, as well as for the areas prone to the sinkholes of natural or human genesis. This paper describes the case of the ground surface collapse occurred in 2013 above the active Saranovsky chromite ore underground mine that has been operating for over eighty years. The results of pre- and post-failure high-precision levelling of the ground surface are presented. The monitoring network includes more than one hundred surveying points covering the area of about 1 km² and since 2006 geodetic measurements have been conducted on an annual basis. The analysis pointed to a complex deformation process, manifested in the cyclic succession of subsidence and uplift of the surface. A local zone of continuous surface subsidence was identified immediately above the site of the future collapse. The deformations started several years before the failure. The extent of the subsiding area increased gradually, approximately approaching the size of the collapse (over 7000 m²). During the three-year period preceding the collapse, this area expanded by over a factor of ten, and the cumulated subsidence rate doubled. However, since the monitoring points located within the sinkhole area were lost, the data of the geodetic campaign carried out before the collapse were insufficient to estimate the value of the subsidence preceding the failure. Our results demonstrate, that in hard rocks mining-induced deformations can develop in utterly localized way. The progression of the subsidence was detected generally within the area of the future failure and did not extend significantly beyond its contours. In this paper, we highlight the importance of further development of the monitoring techniques and justification of hazardous deformation criteria for the early warning systems in mining regions and sinkhole-prone areas.
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Physical factors likely to affect the genesis of the various fault rocks-frictional properties, temperature, effective stress normal to the fault and differential stress-are examined in relation to the energy budget of fault zones, the main velocity modes of faulting and the type of faulting, whether thrust, wrench, or normal. In a conceptual model of a major fault zone cutting crystalline quartzo-feldspathic crust, a zone of elastico-frictional (EF) behaviour generating random-fabric fault rocks (gouge-breccia- cataclasite series-pseudotachylyte) overlies a region where quasi-plastic (QP) processes of rock deformation operate in ductile shear zones with the production of mylonite series rocks possessing strong tectonite fabrics. In some cases, fault rocks developed by transient seismic faulting can be distinguished from those generated by slow aseismic shear. Random-fabric fault rocks may form as a result of seismic faulting within the ductile shear zones from time to time, but tend to be obliterated by continued shearing. Resistance to shear within the fault zone reaches a peak value (greatest for thrusts and least for normal faults) around the EF/QP transition level, which for normal geothermal gradients and an adequate supply of water, occurs at depths of 10-15 km.
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Fault scarps and graben features indicative of slope deformation have been observed adjacent to the rear scarps of landslides and on moorland plateaux in the Pennines. The scarps are distinct, up to 2 m high and can be traced for a maximum distance of approximately 400 m. These severely reduce the strength of the rock mass, enable groundwater to be channelled onto the upper valley slopes and may have played an important role in the initiation of first-time slope failures, and in the reactivation of older landslides. These features are similar to those recently described on the interfluves of the South Wales Coalfield valleys, and are consistent with those described as 'block movements' elsewhere in the world. Those in South Wales have been interpreted, by some previous investigators, as being generated during mining subsidence. However, in the Pennines, the slope and plateaux movements occur in the Namurian (Upper Carboniferous) sedimentary sequences where there has been no mining and it is therefore evident that other mechanisms are involved. In both South Wales and the Pennines steep-sided valleys have incised the moorland plateaux which in both cases are capped by strong, well-jointed cap rocks. These have exposed the underlying, much weaker, fissile mudstones which form the middle and lower slopes. These block movements in the Pennines are documented, discussed and compared with those in South Wales.
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The North Staffordshire Coalfield occupies the northern apex of a triangular area of late Proterozoic continental crust, the Midlands Microcraton. Most faults identified at surface in the late Carboniferous rocks originated either as a result of reactivation of structure during the Variscan orogen in the late Carboniferous, or its collapse in the early Permian. The coalfield has been extensively undermined and many examples of mining-induced fault movement have been recorded in the Barlaston area between 1960-2000. The style of ground deformation observed in the area is described. Most movements have resulted in a series of distinct, extensive, fault scarps and fissures on the ground surface, causing widespread damage to structures, property, underground utilities and land. Several phases of fault movement have occurred, separated by periods of relative stability. Fault scarps may occasionally reach 2 m high, being indicative of multi-seam (3+) mining operations. These are restricted to a few metres in width but reach several hundreds of metres in length. The reasons why so many faults have been reactivated around Barlaston, why the surface expression of the faults are different in Carboniferous and Triassic outcrops, and why some faults appear to have reactivated since the cessation of mining are discussed.
Davis cites four areas of low-angle faulting in which he believes that high fluid pressures can have played no important part in the development and movement of the thrust plates, but it seems to us that the concept or some variant of it may help to explain the observed field relationships in the three out of these four areas with which we have had some first-hand experience. In the areas of the Heart Mountain thrust of Wyoming, the Muddy Mountain thrust of Nevada, and the structurally higher, crystalline thrust sheets of the Swiss Alps, field relationships which include evidence of dehydration reactions during metamorphism of evaporites and of pelitic rocks suggest that interstitial fluid pressures may have been high and thus have played an essential part in the development of the thrust faults. In the fourth area cited by Davis, that of his own studies in the Klamath Mountains of California, we have had no first-hand experience and thus are not competent to answer his criticisms.
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Soluble carbonate rocks often pose a subsidence hazard to engineering and building works, due to the presence of either metastable natural solution features or artificial cavities. There is also an inherent danger to the public and lives have been lost because of unexpected ground collapses. Although site investigation techniques are becoming increasingly elaborate, the detection of hazardous ground conditions associated with limestones is frequently difficult and unreliable. Remedial measures to solve subsidence problems following foundation failure are expensive. It would be advantageous if areas liable to subsidence could be identified in a cost-effective manner in advance of planning and ground investigation. Hazard mapping could then be used by planners when checking the geotechnical suitability of a proposed development or by engineering geologists/geotechnical engineers to design the type of ground investigation best suited to the nature and scale of the potential hazard. Recent research focussed on the English Chalk outcrop has led to the development of two new models to predict the subsidence hazard for both natural solution features and artificial cavities. The predictive models can be used to map the hazard at any given chalkland locality, as a cost-effective precursor to ground investigation. The models, although created for the Chalk outcrop, have important implications for all types of limestone terrain. The basis of the predictive modelling procedure is an analysis of the spatial distribution of nearly 1600 natural solution features, and more than 850 artificial cavity locations, identified from a wide varietyy of sources, including a special appeal organized by CIRIA. A range of geological, hydrogeological and geomorphological factors are evaluated to identify significant relationships with subsidence. These factors are ranked, numerically weighted and incorporated into two quantitative subsidence hazard model formulae. The models can be applied to perform hazard mapping.
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A sudden subsidence under a footpath which led to the tragic death of a pedestrian was followed by a series of further subsidences over a period of several years, all incidents apparently located within an area no more than approximately 1 km square. The area is one of high density housing of the terraced style which was largely developed in the period 1900-1940. Further housing estates have been added in the period since the 1950s. Increasing public concern over the incidents led to the commissioning of a preliminary study by the Rochester-upon-Medway City Council to collate and assess relevant archival information to determine whether the subsidence occurrences in the area could be related to some common cause. The study included reference to local museums, libraries and societies, visits to the British Library Map Department, a review of the geological literature and a collation of the industrial history of the area. Several potential causes of subsidence were discovered; these included the existence of old water wells and dene holes and, more significantly, extensive excavations associated with brick production at the turn of the century. In addition, a canal had been tunnelled under the area in 1823, subsequently partly infilled and converted to railway use. The probable cause of the incidents at Frindsbury has been attributed to the existence of chalk mines associated with the brickfields and further investigation is now taking place to locate these. Clues to all of the features discussed above were available as open file information in public records. This paper describes how the information was acquired and assimilated and emphasizes the importance of the role of desk study in the initial stages of any development project.
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Promise of resolving the paradox of overthrust faulting arises from a consideration of the influence of the pressure of interstitial fluids upon the effective stresses in rocks. If, in a porous rock filled with a fluid at pressure p, the normal and shear components of total stress across any given plane are S and T, then are the corresponding components of the effective stress in the solid alone. According to the Mohr-Coulomb law, slippage along any internal plane in the rock should occur when the shear stress along that plane reaches the critical value where σ is the normal stress across the plane of slippage, τ0 the shear strength of the material when σ is zero, and ϕ the angle of internal friction. However, once a fracture is started τ 0 is eliminated, and further slippage results when This can be further simplified by expressing p in terms of S by means of the equation which, when introduced into equation (4), gives From equations (4) and (6) it follows that, without changing the coefficient of friction tan ϕ, the critical value of the shearing stress can be made arbitrarily small simply by increasing the fluid pressure p. In a horizontal block the total weight per unit area Szz is jointly supported by the fluid pressure p and the residual solid stress σzz; as p is increased, σzz is correspondingly diminished until, as p approaches the limit Szz, or λ approaches 1, σzz approaches 0. For the case of gravitational sliding, on a subaerial slope of angle θ where T is the total shear stress, and S the total normal stress on the inclined plane. However, from equations (2) and (6) Then, equating the right-hand terms of equations (7) and (8), we obtain which indicates that the angle of slope θ down which the block will slide can be made to approach 0 as λ approaches 1, corresponding to the approach of the fluid pressure p to the total normal stress S. Hence, given sufficiently high fluid pressures, very much longer fault blocks could be pushed over a nearly horizontal surface, or blocks under their own weight could slide down very much gentler slopes than otherwise would be possible. That the requisite pressures actually do exist is attested by the increasing frequency with which pressures as great as 0.9Szz are being observed in deep oil wells in various parts of the world.