Sinkholes Research Articles

Recent, slow and aseismic movement of an overthrust observed in the Abel sink hole (Saint-Vallier-de-Thiey, Alpes-Maritimes, France)

The main galleries of the Abel sink hole near Grasse (Alpes Maritimes, France) are developed along a main thrust fault. The study of speleothems clearly proves a recent movement of this fault. The fractures indicate a north-south movement, they are not fossilised by new calcite. A large rock placed under the fault plane rotated during the movement. The soda straws fixed to the rock are curved. This allows an estimation of the movement speed.

Tidally Induced Gap Formation in Protostellar Disks: Gap Clearing and Suppression of Protoplanetary Growth

We present the results of numerical simulations of protostellar accretion disks that are perturbed by a protoplanetary companion that has a much smaller mass than the central object. We consider the limiting cases where the companion is in a coplanar, circular orbit and is initially embedded in the disk. Three independent numerical schemes are employed, and generic features of the flow are found in each case. In the first series of idealized models, the secondary companion is modeled as a massless, orbiting sink hole able to absorb all matter incident upon it without exerting any gravitational torque on the disk. In these simulations, accretion onto the companion induces surface density depression and gap formation centered on its orbital radius. After an initial transitory adjustment, the accretion rate onto the sink hole becomes regulated by the rate at which viscous evolution of the disk can cause matter to diffuse into the vicinity of the sink hole orbit, and thus the sink hole grows on a disk viscous timescale. In the second series of comprehensive models, the companion's gravity is included. When the tidal torque exerted by the companion on the disk becomes important, the angular momentum exchange rate between the companion and the disk induces the protoplanetary accretion to reduce markedly below that in the idealized sink hole models. Whether this process is effective in inhibiting protoplanetary accretion depends on the equation of state and disk model parameters. For polytropic or isothermal equations of state, we find, in basic agreement with earlier work, that when the mean Roche lobe radius of the companion exceeds the disk thickness and when the mass ratio, q, between the companion and the central object exceeds ~40/, where is the effective Reynolds number, a clean deep gap forms. Although precise estimation is rendered difficult due to the limitation of numerical schemes in dealing with large density contrasts, the generic results of three series of simulations indicate that accretion onto sufficiently massive protoplanets can become ineffective over the expected disk lifetimes in their neighborhood. We suggest that such a process operates during planetary formation and is important in determining the final mass of giant planets.

Comparison of stormwater management in a karst terrane in Springfield, Missouri — case histories

Control of stormwater in sinkhole areas of Springfield, MO has involved the utilization of several standard approaches: concrete-lined channels draining into sinkholes; installation of drainage pipes into the sinkhole “eyes” (swallow holes); filling of sinkholes; elaborate drains or pumps to remove stormwater from one sinkhole and discharging into another drainage basin or sinkhole; and enlargement of swallow holes by excavation to increase drainage capacity. Past planning considerations and standard engineering approaches have resulted in flooding of sinkholes and drainage areas, including residential, industrial and commercial developments. Having recognized the inadequacy of existing designs to control flooding and the need to accommodate increased runoff from future development, the City of Springfield adopted an ordinance (effective 19 June 1989 and modified in 1990 and 1993) in response to public pressure and concerns over flooding in sinkholes and sinkhole drainage areas. Three sites were analyzed to examine the effectiveness of contrasting design approaches to stormwater management. These sites differ in vegetation, on-site/off-site considerations, and types of development proposed. All three sites are located within the East Cherry Street Sinkhole Area. The first site, a wooded tract with unmodified sinkholes was cleared and developed for residential use. Discharge of stormwater was directed into sinkholes, and erosion control consisted of hydro-mulching and sedimentation fences in sinkhole areas. East of this location are two parcels which differ in removal of vegetation and off-site drainage relationships. Stormwater design in these sites was adapted for modifications made to sinkholes during railroad and highway construction several decades earlier. Sediment fencing, hydro-mulching and detention berms augment infiltration, restrict erosion, retard discharge to sinkholes, and incorporate off-site considerations. Ongoing observations of stormwater behavior indicate problems of flooding and sediment control at the western site but minimal disruptions of existing drainage patterns at the eastern sites. Design calculation for the western site show adequate volume retention in sinkholes, but different design approaches were implemented to “soften” the impact of stormwater discharging into these sinkholes, allowing for minimal disruptions in the natural drainage network. The lack of recognition of sinkholes as integral parts of dynamic hydrologic systems may result in problems with on-site/off-site drainage. Standard engineering designs for stormwater detention are not appropriate for the hydraulic characteristics of the shallow karst drainage network. While runoff estimations are conservative, the design calculations fall short of adequately addressing actual stormwater runoff characteristics.

Characterizing the Distribution of Near‐Surface Solution Channels Using Electromagnetic Induction and Ground Penetrating Radar

A series of four ponds were developed at a sewage treatment facility in southwestern Oklahoma. Three of these four ponds, when put into service, failed to hold water. The reason for this is that the hydraulic head produced by the water in these ponds caused sink holes to develop into a shallow gypsum formation allowing this water to drain. In order to evaluate potential strategies to mitigate this problem, it was first necessary to establish the horizontal extent and depth interval of the solution channels beneath the sewage treatment ponds. To reach this end, electromagnetic induction (EMI) and ground penetrating radar studies were performed at these ponds. The EMI data showed a distribution of apparent low electrical conductivity regions that correlated well with the pattern of open sink holes. Two‐ and three‐dimensional images reconstructed from the GPR data provided confirmation of the EMI results and established a depth to the voids of about 40 cm.

Reservoir Implications of Modern Karst Topography

Tropical karst landscapes exhibit a predominance of positive relief features relative to the negative relief features (i.e., sink holes, dolines, etc.) of temperate karst areas and yet, paradoxically, have never been observed in the subsurface on seismic sections. To understand why this is the case, topographic profiles were made over the positive karst relief features of China, Java, and Jamaica and were used to construct synthetic seismic sections. The results indicate that in most instances the magnitude of the topographic relief is sufficient to be seen on seismic sections. A possibility of misinterpreting karst highs as reefs seems clear, but more important in explaining the paradox is the fact that the magnitude of modern karst relief expression is largely attributable to uplift over an extended period. The probability of preservation of these positive relief solution residuals is dependent on the karstification process being aborted by the deposition of overlying sediment, an event not likely to occur in an uplift area. Uplift of well-lithified carbonate minimally results in an areally extensive runoff surface that controls the development of positive karst landforms. Uplift also commonly induces faulting and fracturing that further control the distribution of karst land forms. Hydrocarbon production from the resulting karst is geared to matrix porosity: the higher the matrix porosity, the greater the rate of deliverability of matrix oil to produced fracture and karst conduit oil. In contrast, the lowering of the base level of erosion due to a fall in sea level is generally less than that induced by uplift and, consequently, minimizes positive karst relief development relative to that of uplift. Subaerial exposure induced by passive sea level fall also minimizes the potential for the related occurrence of fracturing and faulting, which of itself mitigates against the general development of positive karst relief. The subaerial consequences of passive sea level fall are commonly preserved in the geologic record and result in karst reservoirs dominated by extensive moldic and vuggy porosity interconnected by solution channels. These reservoirs lack the production problems commonly attending fractured karst reservoirs with little matrix porosity.

A submerged stalactite from Belize: Petrography, geochemistry, and geochronology of massive marine cementation

Submerged sink holes and cave systems associated with oceanic limestone platforms often contain speleothems and dripstone features which formed during subaerial exposure during glacially lowered sea level. A large stalactite, collected from a 50 meter deep terrace within the “Blue Hole” on Lighthouse Reef, offshore from Belize, records the geochronology of the transition from subaerial exposure to marine submergence during Holocene sea level rise. The stalactite originally formed on the ceiling of a large cavern when sea level was at least 60 meters below its present stand. As sea level rose, flooding the cavern, the fresh water phase of dripstone formation terminated and a 12 cm-thick rind of botryoidal splays of radial-fibrous marine aragonite coated the stalactite. This is the most massive encrustation of Holocene marine cement known, and it precipitated from seawater which had been considerably modified during circulation through the carbonate platform. By approximately 3000 yBP, when sea water flooded the bank top, cement accretion had ended, and the complex speleothem was encrusted by a marine biolithite prior to falling to the mud-covered floor of the cavern.

Understanding groundwater sources and movement using water chemistry and tracers in a low matrix permeability terrain: the Cretaceous (Chalk) Ulster White Limestone Formation, Northern Ireland

The Cretaceous Chalk [Ulster White Limestone Formation (UWLF)] in Northern Ireland has been diagenetically altered to a hard, low porosity, low matrix-permeability rock. It subcrops extensive beneath thick horizontal Tertiary Basalt lavas, but has a restricted strip of outcrop (approximately 80 km 2) around the periphery of the overlying igneous rock. Despite its nature and location, numerous springs issue from the Chalk and are used for public and local supply, although little is known about the origin of the groundwater or the type of flow within the Chalk. We have addressed these unknowns using hydrogeochemical data from both rock types and surface stream waters, and fluorescent dye tracing. We have demonstrated that leakage recharge from the basalt to the Chalk accounts for less than 20% of the total water issuing from the Chalk springs using geochemical mass balance of conservative species and discharge data. The majority of the discharge derives from streams coming off the basalt and entering sink holes in the Chalk aquifer. Field and water tracing evidence shows that groundwater flow in the Chalk is dominated by conduit and fissure flow near to the outcrop areas. Karstification has been widespread near outcrop but has not ocurred in the sub-basalt region. Beneath the basalts, the Chalk exhibits different hydraulic properties due to the reduced recharge and dissolution potential that has prevented extensive development of fissure permeability in the UWLF. The Chalk aquifer thus appears to be strongly zoned in terms of the source of water, flow regime and recharge rate.

Sink Hole Could Swallow Climate Pact

Sink Hole Could Swallow Climate Pact

The Fabulous Sinkhole and Other Stories

The Fabulous Sinkhole and Other Stories

An Algorithm and a C-program Source for Automated Drainage Network Extraction

We developed a flooding-type algorithm for drainage network extraction and show a full program source in the language C. The program generates automatically Drainage Direction Matrices (DDMs) from Digital Elevation Models (DEMs) with sink holes. By using a random technique of random walk type, the drainage networks are processed adequately in flat plains or alluvial fans.

A hazard map of the Magnesian Limestone in County Durham

Abstract A large part of County Durham is underlain by carbonate rocks of Permian age, principally Magnesian Limestone. In recent years problems have been encountered in constructing on the Permian carbonates, due to dissolution followed by subsidence and/or sink hole formation. Features believed to be triggers for dissolution of limestone have been mapped and a weighted factor hazard map has been created. The map is based on an extensive review of existing site investigation data including a study of aerial photographs. Records of dissolution features noted by the County Council engineers have been incorporated into the hazard map. The map is intended as a guide for County Council Engineers who are planning site investigations within the area. The preparation of the map and its limitations are discussed.

Shallow High-Resolution Seismic Reflection to Delineate Upper 400 m around a Collapse Feature in Central Kansas

Abstract Shallow seismic reflection techniques successfully delineated reflectors altered by localized dissolution of the 400-m-deep and 125-m-thick Permian Hutchinson Salt Member in central Kansas. The Hutchinson Salt Member underlies ~120,000 km2 of central Kansas and north central Oklahoma. Three nominal 48-fold seismic reflection profiles were acquired around a gradually subsiding sinkhole in central Kansas. Seismic images of the altered salt interval possess more detail and greater resolution potential than do profiles from previous high-resolution seismic reflection attempts to map dissolution altered zones for appraisal of risk, rate, and extent of future surface subsidence. The common depth point (CDP) stacked sections possess a dominant frequency of ~100 Hz at 400 m and therefore a vertical resolution potential of ~3 m. Roof failure and staggered subsidence of units overlying the salt is evident and suggestive of continued subsidence at nonuniform rates. The interpreted presence of both normal and reverse faulting within this 90,000-m2 area is indicative of at least two unique episodes of subsidence, each controlled by dramatically different stress environments. The prominent reflections from within the 125-m-thick salt are from anhydrite layers laterally continuous over several tens of kilometers. These anhydrite layers act as markers on seismic sections to identify clearly the shape and preferential orientation of the disturbed area within the salt. Roof failure and collapse within the salt interval are acoustically represented by a chaotic zone, likely indicative of a rubble area. The >15 msec of relative difference in subsidence between the shallowest reflection and the Stone Corral Anhydrite reflection (an interval of ~250 m) along the southern and eastern portions of this sinkhole suggests subsidence will likely continue in these areas. A low fold, minimal deployment three-dimensional (3-D) survey designed around common offset and shallow seismic reflection techniques was acquired to evaluate the potential of minimal deployment 3-D and to evaluate better the lateral variability of the interpreted faults at this sinkhole. Significant potential exists for this technique in delineating specific targets critical to shallow site characterization. The high cost and high technological nature as well as many assumptions appropriate for deeper petroleum problems are not realistic or feasible for near surface applications. This data set demonstrates the effectiveness and potential as well as some of the problems of minimal deployment 3-D surveys to delineate major structural features.

SEDAAG Maps: A Swift and New Perspective on Geographic Growth?

Professor Wheeler has put together an interesting map depicting growth in the number of full-time faculty in geography departments in the Southeastern Division ofthe Association ofAmerican Geographers over the last 10 years (Wheeler, 1996). This is certainly encouraging to all geographers, and hopefully it reflects a greater commitment by central administrators to the value ofa geographic education. It is, ofcourse, noteworthy that not only have some departments expanded, but that there also has been an increase in the spatial distribution of geography faculty members. The map is indeed filling in. On the other hand, the map raises questions. As trained geographers, we examined the mapped data very carefully looking for telling spatial patterns, temporal trends, or for the occurrence of spatial inequalities. In this context, the lacuna of geographers in central-west Florida hit us most profoundly. Was this really a desert geo-scape devoid of the geographically inclined? Perhaps an explanation was necessary. We hypothesized that the lack ofgeographers in the Tampa Bay region could be explained by the hazardousness of place; to wit, a natural disaster had eliminated all geographers between Tallahassee, Gainesville, and Miami. The sink hole theory did not hold water, being too limiting in size, while the earthquake concept was faulted from the beginning. This left the tropical storm hypothesis; had a hurricane, equivalent to the Galveston event of 1900, obliterated all those intellectuals? Subsequent research, however, revealed that hurricanes were probably not that selective in eliminating only those residing in ivory towers. We were clearly missing that significant variable. Looking at this from a different perspective (Fig. 1), the pattern became more clear. Something major had occurred in the central Florida wetlands. Further investigation revealed that an invasion ofBermuda-shorted exotic species, led by a

Evaporite karst of Northern Lower Michigan

Michigan has three main zones of evaporite karst: collapse breccia in Late Silurian deposits of the Mackinac Straits region; breccia, collapse sinks, and mega-block collapse in Middle Devonian deposits of Northern Lower Michigan, which overlaps the preceding area; and areas of soil swallows in sinks of Mississippian deposits between Turner and Alabaster in Arenac and Iosco counties, and near Grand Rapids in Kent County. The author has focused his study on evaporite karst of the Middle Devonian deposits. The Middle Devonian deposits are the Detroit River Group: a series consisting of limestone, dolomite, shale, salt, gypsum, and anhydrite. The group occurs from subcrop, near the surface, to nearly 1400 feet deep from the northern tip of the Southern Peninsula to the south edge of the “solution front.” Glacial drift is from zero to 350 feet thick. Oil and gas exploration has encountered some significant lost-circulation zones throughout the area. Drilling without fluid returns, casing-seal failures, and lost holes are strong risks in some parts of the region. Lost fluid returns near the top of the group in nearby areas indicate some karst development shortly after deposition. Large and irregular lost-circulation zones, linear and patch trends of large sink holes, and 0.25 mile wide blocks of down-dropped land in the northern Lower Peninsula of Michigan were caused by surface-and ground-water movement along faults into the Detroit River Group. Glaciation has removed some evidence of the karst area at the surface. Sinkhole development, collapse valleys, and swallows developed since retreat of the glacier reveal an active solution front in the Detroit River Group.

The Arecibo Observatory

The Arecibo radar and radio telescope stands on a triangular platform as it hovers 220 m above the ground. The spherical dish resides in a natural sink hole, one of the largest in Puerto Rico. This platform is the focal point of an isolated scientific outpost where staff and students ply their trade. The Arecibo Observatory is a US national laboratory managed by Cornell University (New York) through a cooperative agreement with the National Science Foundation (NSF). The bulk of the astronomy work done focuses on stellar evolution, galaxy formation, and pulsars.

Do you have the partners you need to survive

I am pleased to be invited to speak on the issue of partnerships and collaboration between information specialists, librarians and computer/technology specialists. Over the past several years, I have indeed given considerable thought and time on just this issue through work on my campus and in the national arena within CNI & Educom. There are many opportunities that exist but also many sink holes that await us both in ignoring these opportunities AND in pursuing them. I believe that our two professionals groups - library and computing professionals - have a significant leadership role to play and contributions to make in our respective institutions and that these contributions will be that much greater if we work together rather than separately.

A stepped karst unconformity as an Early Silurian rocky shoreline in Guizhou Province (South China)

Where succeeded by marine strata, karst unconformities signify a former rocky coastline. Such relationships may help sort out relative sea-level changes and aspects of local geography controlling facies distribution. An exceptional example of an early Silurian karst shore is well exposed near the village of Wudang in central Guizhou Province, near the capital city of Guiyang in South China. Here the Lower Silurian Kaochaitien Formation oversteps 63 m of paleotopographic relief in limestones belonging to the Llanvirn Guniutan Formation and Caradoc to early Ashgill Huanghuachong Formation (Ordovician). The corresponding rise in sea level took place coeval with tectonic uplift, as confirmed by a regionally diachronous relationship in the Ordovician-Silurian boundary across a 250 km track from central to northern Guizhou Province. The change in sea level also fits with a global rise of sea level in late Aeronian (later Llandovery, early Silurian) time. Borings of the ichnofossil, Trypanites, are reported from the karst surface of the Huanghuachong Formation and Silurian strata fill sink holes in this unit over 5 m deep. The Silurian karst shoreline near Wudang is integrated with other regional data to construct a paleogeographic map covering the northern half of Guizhou Province.

Identification of Depth in South-Western Bosnia Using the Tracer Method

The Glamocko Polje is the surface and underground watershed between the river basins of the Black Sea and the Adriatic Sea. The recharge areas of groundwater, flow towards the Bistrica, Zabljak, and Duman springs (in the Livanjsko Polje and River Cetina basins) towards the south; to the Ribnik and Sana river springs towards the north, and to the Pliva and Janja river springs. Complicated thrust tectonics, hanging and deep-lying hydrogeological barriers give rise to complicated hydrogeological relations. Groundwater tracing helped to determine the position of watersheds and depths to groundwater in this part of the Dinaridic karst. Water discharge at the named springs is controlled (besides the temporary flooding of the poljes), by groundwater karst conduits from the swallow holes to the springs.

Hydrogeology Of Slanac Spring, Croatia

The brackish karst spring Slanac is located at an unusually high altitude of 30 m a.s.l. and is 1,250 m from the Adriatic Sea. Slanac spring, the permanent brackfish karst spring Pantan, and two submarine springs (vruljes), Arbanija and Slatina, represent outflows from a single karst aquifer. Slanac spring is only active immediately after heavy rainfall greater than 50 mm/day. The water discharged by the spring is always saline. When the spring first becomes active, its salinity is 18,000 mg/l. Salinity declines to 1,000 mg/l as the spring's activity comes to an end. The intrusion of a sea water is explained by the existence of a suspended hydrogeologic barrier and by the vruljes acting as temporary submarine swallow holes that draw in sea water during the dry period of the year. By using hydraulic analyses and assuming a turbulent flow regime of fresh-water circulation in karst conduits, it was possible to assess diameters, absolute hydraulic roughnesses, and discharges of the four main conduits that supply fresh water from the aquifer to Slanac spring and to Arbanija and Slatina vruljes.

The Chalk as a karstic aquifer: evidence from a tracer test at Stanford Dingley, Berkshire, UK

Abstract Karstic features such as swallow holes and dolines are the rule rather than the exception in the Chalk outcrop of southern England, particularly in the region of the Chalk/Tertiary boundary. Previous tracer tests at Bedhampton and Water End have indicated groundwater transport velocities of 2.2 and 5.5km/day. A recent tracer test at Stanford Dingley in Berkshire has indicated comparably high transport velocities in the Chalk: 5.8km/day for peak tracer concentration, and 6.8km/day for tracer breakthrough. In all three cases the swallow hole systems were able to transmit turbid surface run-off contamination over large distances, indicating a short-circuiting of the natural attenuating properties of the unsaturated and saturated zones. In the light of this, the practice of using swallow holes to dispose of agricultural- and road-run-off should be discouraged.