Geologic hazards in Oklahoma

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Authors:Luza, Kenneth V.; Johnson, Kenneth S.
Author Affiliations:Primary:
Oklahoma Geological Survey, United States
Source:Information Series - Oklahoma Geological Survey, No.11, 21p. Publisher: Oklahoma University, Oklahoma Geological Survey, Norman, OK, United States
Publication Date:2005
Note:In English. 49 refs.
Summary:Natural geologic processes that have caused or might cause hazardous conditions in Oklahoma include earthquakes, landslides, expansive soils, floods, karst/salt dissolution, and radon. At least four principal areas of seismic activity have been identified in the State: El Reno-Mustang, central Oklahoma; an area in south-central Oklahoma on the eastern margin of the Anadarko Basin; Love and Carter Counties, central southern Oklahoma; and an area north of the Ouachita Mountains in the Arkoma Basin of southeastern Oklahoma. Most Oklahoma landslides occur in the eastern one-third of the State, owing to a wetter climate and steeper slopes associated with a more mountainous terrain. Many clay-rich shales, or soils derived from the weathering of shales, contain clay minerals, such as montmorillonite, that swell to as much as 1.5 to 2.0 times their original dry volume when they are wetted. More than 75% of Oklahoma contains bedrock units that have the ability to serve as sources of expansive soils. Although floods can occur in any month in Oklahoma, major floods frequently occur in the spring and fall months. Flood-prone areas in Oklahoma have been identified and mapped by the U.S. Geological Survey, the U.S. Army Corps of Engineers, and private contractors. This mapping program is intended to delineate those areas that have, on average, about 1 chance in 100 of being inundated in any particular year. Water-soluble rocks, such as limestone, dolomite, gypsum/anhydrite, and/or salt, are prone to the development of karst and dissolution features from the dissolving action of circulating ground waters. The sinkholes and caverns thus developed are potential hazards, owing to possible settlement or collapse of the land surface into the underground openings. Principal areas in Oklahoma where karst features are present in limestone and dolomite are the Ozark Mountains in northeastern Oklahoma, the Arbuckle Mountains in south-central Oklahoma, and the Limestone Hills (north of the Wichita Mountains) of southwestern Oklahoma. Gypsum and shallow salt deposits are present in many areas of western Oklahoma. Approximately 80% of the State is underlain by formations with uranium contents that are equal to, or less than, the crustal average (2.5 ppm). The U.S. Environmental Protection Agency identified nine Oklahoma counties that have a moderate potential for elevated indoor radon levels. Some activities of man that have created present, or might create future, geologic hazards in Oklahoma include disposal of industrial wastes, underground mining, and strip mining. Solid and liquid industrial wastes have been disposed of in some areas of Oklahoma by surface burial in soil or rock units. Rock units in the State most favorable for surface disposal of wastes are impermeable sedimentary rocks, such as shale and clay, that can be excavated and that can prevent loss or migration of wastes from the disposal pit. Rock types in Oklahoma that are most desirable for surface disposal are porous and permeable sedimentary rocks, such as sandstone, limestone, and dolomite, that can store injected liquid wastes. These porous and permeable rock units should be surrounded by impermeable strata to assure containment. Underground mines associated with the extraction of zinc/lead in Ottawa County in northeastern Oklahoma, and coal in the eastern Oklahoma coal field, along with a small number of underground gypsum, limestone, base-metal, and asphalt mines in other districts, are current and potential hazards because of the following possible problems: (1) collapse of roof rock, causing subsidence or collapse at the land surface; (2) the presence of acidic or toxic ground water; and (3) flooding of a new mine by accidentally breaking into a water-filled abandoned mine. Lands disturbed through surface mining are potential problem areas because (1) spoil piles and fill material might not be fully compacted, and might still be subsiding or settling; (2) ponds and ground water in the mined areas might be acidic and/or toxic; and (3) highwalls and quarry faces might contain loose rocks or unstable slopes. Of all commodities mined by surface techniques, the extraction of coal has had the greatest impact on the environment in Oklahoma.
Subjects:Earthquakes; Expansive materials; Floods; Geologic hazards; Karst; Landslides; Mass movements; Mining; Noble gases; Radon; Soils; Underground mining; Waste disposal; Waste management; Oklahoma; United States
Record ID:2005053994
Copyright Information:GeoRef, Copyright 2018 American Geosciences Institute.
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