SEARCH · Search USGS
Results for “Engineering Geology”
Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Engineering geologic conditions at the sinkhole entrance to Logan Cave, Benton County, Arkansas
Logan Cave, located in Benton County, Arkansas, is inhabited by several endangered and threatened species. The cave and surrounding area was designated a National Wildlife Refuge under the control of the U.S. Fish and Wildlife Service (USFWS) in 1989. Cave researchers access the cave through a steep-sided sinkhole entrance, which also is one of the two access points used by endangered bats. There is evidence of instability of one of the entrance slopes that has raised concerns that the entrance could close if slope failure was to occur. At the request of USFWS, we performed an engineering geologic investigation of the sinkhole to evaluate stability of this slope, which is comprised of soil, and other mechanisms of sediment transport into the cave entrance. The investigation included engineering geologic mapping, sampling and laboratory testing of subsurface geologic materials, and slope-stability analysis. We found that the sinkhole slope that extends into the entrance of the cave is comprised of sandy and gravelly soil to the depths explored (6.4 meters). This soil likely was deposited as alluvium within a previous, larger sinkhole. Based on properties of the alluvium, geometry of the slope, and results of finite-element slope-stability analyses, we conclude that the slope is marginally stable. Future failures of the slope probably would be relatively thin and small, thus several would be required to completely close the cave entrance. However, sediment is accumulating within the cave entrance due to foot traffic of those accessing the cave, surface-water erosion and transport, and shallow slope failures from the other sinkhole slopes. We conclude that the entrance will be closed by sediment in the future, similar to another entrance that we identified that completely closed in the past. Several measures could be taken to reduce the potential for closure of the cave entrance, including periodic sediment removal, installation of materials that reduce erosion by foot traffic and surface water, construction of a sediment-retention wall, and excavation of the soil slope. Any measures taken must be carefully planned and executed so that they have no impact on organisms within the cave.
Reconnaissance engineering geology of the Ketchikan area, Alaska, with emphasis on evaluation of earthquake and other geologic hazards
The Alaska earthquake of March 27, 1964, dramatically emphasized the need for engineering geologic studies of urban areas in seismically active regions. A reconnaissance study of the Ketchikan area in southeastern Alaska is part of a program to evaluate earthquake and other geologic hazards in most of the larger Alaska coastal communities. These evaluations in the Ketchikan area should provide broad guidelines useful in city and land-use planning. Ketchikan, which had a population of approximately 7,000 in 1970, is built on the southwestern end of Revillagigedo Island along the northeastern coastline of Tongass Narrows. Altitudes reach 1,000 feet (305 m) within half a mile (0.8 km) of the coast and near-vertical cliffs characterize the terrain in places. The climate is predominantly marine. Average precipitation is approximately 152 inches (386 cm). The Ketchikan area was covered by glacier ice at least once and probably several times during the Pleistocene Epoch. The present topography, characterized by elongate lakes, U-shaped valleys, fiords, inlets, and passages, clearly reflects the effects of glaciation. The presence of emergent marine deposits, at least 300 feet (91 m) above sea level, shows that the land has been uplifted relative to sea level since the last deglaciation of the region. Bedrock is exposed or is near the surface throughout most of the mapped area. The bedrock consists chiefly of metamorphic rocks. In a few places these rocks have been intruded by igneous rocks. Exposed metamorphic rocks are mostly thinly foliated schists and phyllites, metamorphosed to greenschist facies. Foliation generally strikes northwest with moderate to steep dips to the northeast. Most of the rock is fairly competent and near-vertical cuts tend to be stable. The more indurated metamorphic rock can be used for riprap, but more durable blocks generally can be obtained from the igneous rock. The surficial deposits have been divided into the following map units on the basis of their time of deposition, mode of origin, and grain size: (1) undifferentiated drift (Qd), (2) elevated marine deposits (Qm), (3) stream alluvium (Qa), (4) fan-delta deposits (Qf), and (5) modern beach deposits (Qb). Manmade fill (f) also is mapped as a separate unit. Muskeg, colluvium, and offshore deposits are not included as map units but are discussed in the report under the heading "Surficial deposits (not shown on map)." The undifferentiated drift deposits consist mostly of till or other diamictons, generally less than 25 feet (7.6 m) thick. Exposed elevated marine deposits (Qm) generally consist of sand and gravel less than 5 feet (1.5 m) thick. Stream alluvium (Qa) is chiefly sand, gravel, cobbles, and boulders probably everywhere less than 15 feet (4.6 m) thick. Fan-delta deposits (Qf) consist mostly of loose sand, gravel, and boulders as much as 50 feet (15 m) thick. Modern beach deposits (Qb) are mostly loose sand and gravel generally less than 10 feet (3 m) thick. Two basically different types of manmade fill are present: (1) large fills along the waterfront, commonly 5 to 15 feet (1.5-4.6 m) thick, consisting of silt, sand, gravel, rock, and diverse other materials, and (2) fills, generally less than 10 feet (3 m) thick and consisting of sand, gravel, or crushed rock, placed inland from the waterfront and used as pads for buildings and parking areas. Fairly thick deposits of muskeg may be present in the southeastern part of the mapped area but have not been examined in the field. Colluvial deposits, locally 5 to 8 feet (1.5-2.4 m) thick, consist mostly of decomposing bedrock fragments. Offshore deposits are poorly known; near-shore loose sand and gravel rest on a sloping bedrock surface. Southeastern Alaska lies within the circum-Pacific seismic belt that rims the northern Pacific Basin and has been tectonically active since at least early Paleozoic time. Large-scale faulting has been common. The two most prominent fault systems in southeastern Alaska and surrounding regions are (1) the Denali fault system, and (2) the Fairweather-Queen Charlotte Islands fault system. Of the two, the Fairweather-Queen Charlotte Islands fault system is the more active and of most significance in relation to the Ketchikan area. Ketchikan lies within the northwest trend of the Gravina-Nutzotin belt of fault thrusting. The trends of at least some of the linear fiords near the mapped area are controlled by faults. However, it is not known whether a major fault extends up Tongass Narrows offshore from Ketchikan. Between 1899 and 1970, five earthquakes having magnitudes of 8 or greater occurred in or near southeastern Alaska or in adjacent offshore areas; three have occurred having magnitudes of between 7 and 8, at least eight with magnitudes of between 6 and 7, 15 with magnitudes of between 5 and 6, and about 140 have been recorded with magnitudes of less than 5 or of unassigned magnitudes. All of the earthquakes with magnitudes greater than 8, and a large proportion of the others, appear to be related to the Fair-weather-Queen Charlotte Islands fault system or to the connecting Chugach-St. Elias fault to the northwest. Within a 50-mile (80-km) radius of Ketchikan, epicenters of three earthquakes with magnitudes of 5 or less have been recorded. Within a radius of 100 miles (160 km), 10 epicenters have been recorded, two with magnitudes between 6 and 7 and eight with magnitudes of 5 or less. Although no instrumentally recorded earthquakes had epicenters in the mapped area, at least 32 earthquakes that had epicenters elsewhere were felt or possibly felt in Ketchikan. Most of these earthquakes probably had epicenters along the Queen Charlotte Islands fault. Ketchikan is tentatively assigned by me to seismic zone 2. This is a zone in which magnitudes of the largest expectable earthquake would range from 4.5 to 6.0 and where moderate damage could be expected. Large earthquakes of magnitude 8 or greater, however, can be expected to occur from time to time along the Queen Charlotte Islands fault. Ground motion from these earthquakes, although attenuated with distance, may still be sufficiently strong at Ketchikan to cause substantial damage. Possible future earthquake effects include: (1) land-level changes caused by local faulting or by large-scale regional deformation, (2) ground shaking, (3) compaction, (4) liquefaction, (5) subaerial and submarine sliding, (6) water-sediment ejection and ground fracturing, (7) reaction of sensitive and quick clays, and (8) effects of tsunamis, seiches, and other abnormal water waves. Although land-level changes due to local faulting are unlikely, large-scale regional deformation may cause uplift or subsidence in Ketchikan. Adverse effects would be confined mainly to the waterfront area. This area also would be most heavily damaged if Ketchikan were strongly shaken by an earthquake. Nonengineered, loose, manmade fills and fan-delta deposits in this area probably would be subject to the strongest shaking. These deposits probably also are most subject to compaction, liquefaction, sliding, and water-sediment ejection. Earthquake effects expectably would be considerably fewer and less severe for the part of Ketchikan upslope from the harbor area because bedrock is at or near the surface in large parts of the area. No sensitive clays have been identified but, if present, they probably are confined to the till and other diamicton deposits in the northeastern part of the mapped area. Tsunami waves are not expected to have a local generation source. Those arriving from a distant source, although potentially highly destructive, probably would be greatly attenuated before arriving at Ketchikan. Seiche waves may develop on lakes near the mapped area and possibly cause failure of earth-fill dams. Destructive waves generated by earthquake-induced local submarine sliding appear to be unlikely in the Ketchikan area. Geologic hazards in the area that are not caused by earthquakes are believed to be relatively minor. They include: (1) landsliding and subaqueous sliding, and (2) flooding. Only minor landsliding has occurred in the mapped area, but the potential for sliding may increase as the city expands and heavily timbered areas are cleared, with attendant accelerated erosion and mass wasting. The greatest potential for subaqueous sliding is along the shoreline, where fairly thick fan-delta deposits rest on a sloping bedrock surface. Periodic flooding has occurred on some creeks in the mapped area and can be expected to occur from time to time in the future. In order that more accurate evaluations of geologic hazards can be made in the future, several recommendations are made for additional studies.
Ancient engineering geology projects in China; A canal system in Ganzu province and trenches along the Great Wall in Ningxia Hui Autonomous Region
Two major construction projects of ancient times in China involved what today would be considered engineering geology. We describe an ancient canal system in Gaotai County, Gansu province that was possibly begun in the Han dynasty (206 BC-220 AD). The canal system heads at the Dasha River and extends northwestward for about 55 km to the City of Camels and Xusanwan village. Four parallel canals are present at the local site we examined. The canals were likely built primarily to transport water but may also have served as defensive military barriers. A second project involves trenches and berms along the north side of the Great Wall, clearly part of the Great Wall defensive system. This site is in Ningxia Autonomous Region near the town of Shizuishan. ?? 1994.
Reconnaissance engineering geology of the Haines area, Alaska, with emphasis on evaluation of earthquake and other geologic hazards
The Alaska earthquake of March 27, 1964, brought into sharp focus the need for engineering geologic studies in urban areas. Study of the Haines area constitutes an integral part of an overall program to evaluate earthquake and other geologic hazards in most of the larger Alaska coastal communities. The evaluations of geologic hazards that follow, although based only upon reconnaissance studies and, therefore, subject to revision, will provide broad guidelines useful in city and land-use planning. It is hoped that the knowledge gained will result in new facilities being built in the best possible geologic environments and being designed so as to minimize future loss of life and property damage. Haines, which is in the northern part of southeastern Alaska approximately 75 miles northwest of Juneau, had a population, of about 700 people in 1970. It is built at the northern end of the Chilkat Peninsula and lies within the Coast Mountains of the Pacific Mountain system. The climate is predominantly marine and is characterized by mild winters and cool summers. The mapped area described in this report comprises about 17 square miles of land; deep fiords constitute most of the remaining mapped area that is evaluated in this study. The Haines area was covered by glacier ice at least once and probably several times during the Pleistocene Epoch. The presence of emergent marine deposits, several hundred feet above sea level, demonstrates that the land has been uplifted relative to sea level since the last major deglaciation of the region about 10,000 years ago. The rate of relative uplift of the land at Haines during the past 39 years is 2.26 cm per year. Most or all of this uplift appears to be due to rebound as a result of deglaciation. Both bedrock and surficial deposits are present in the area. Metamorphic and igneous rocks constitute the exposed bedrock. The metamorphic rocks consist of metabasalt of Mesozoic age and pyroxenite of probable early middle Cretaceous age. The igneous rocks consist of diorite and quartz diorite (tonalite) of Cretaceous age. Sedimentary rocks of Tertiary age may be present in the mapped area but are not exposed. The surficial deposits of Quaternary age,-have been divided into the following map units on the basis of time Of deposition, mode of origin, and grain size: (1) undifferentiated drift deposits, (2) outwash and Ice-contact deposits; (3) elevated fine-grained marine deposits, (4) elevated shore and delta deposits, (5) alluvial fan deposits, (6) colluvial deposits, (7) modern beach deposits, (8) Chilkat River flood-plain and delta deposits, and (9) manmade fill. Offshore deposits are described but are not mapped. Southeastern Alaska lies within the tectonically active belt that rims the northern Pacific Basin and has been active since at least early Paleozoic time. The outcrop pattern is the result of late Mesozoic and Tertiary deformational, metamorphic, and intrusive events. Large-scale faulting has been common. The two most prominent inferred fault systems in southeastern Alaska and surrounding regions are: (1) The Denali fault system and (2) the Fairweather-Queen Charlotte Islands fault system. In the general area of Haines, rocks of Mesozoic age northeast of Chilkat River have a simple monoclinal structure. Paleozoic-Mesozoic rocks southwest of Chilkat River are gently to rather complexly folded. Several major and numerous minor faults probably transect the general area of Haines but their exact location and character can only be inferred because their traces are coincident to the long axes of fiords and river valleys, where they are concealed by water or by valley-floor deposits. Inferred faults in or near the Haines mapped area are: (1) Chilkat River fault, (2) Chilkoot fault, (3) Takhin fault, and (4) faults in the saddle area at Haines. Southeastern Alaska lies in one of the two most seismically active zones in Alaska, a State where 6 percent of the world's shallow earthqua
Engineering geology investigation, Little Granite Creek road corridor, Teton National Forest, Teton County, Wyoming
This report summarizes the results of an engineering geology investigation for the proposed Little Granite Creek Road Corridor access to the Getty drill site. The purpose of the investigation was to provide geologic data so that the U.S. Forest Service and U.S. Geological Survey can jointly draft an Environmental Impact Statement. The location of the proposed road corridor is shown on Fig. 1. The general geologic conditions within the corridor are described and their anticipated impacts on the proposed road are discussed. The data and conclusions presented in this report are suitable for evaluating general impacts; however, additional detailed studies will be required for final design purposes. The geologic conditions in the proposed road corridor were evaluated by reviewing published regional geologic maps, a field reconnaissance, and interpretation of aerial photographs. The largest scale geologic map available for the area is the 1:24,000, Geologic Map of the Bull Creek Quadrangle, Schroeder (1976). In early October, 1980, a field reconnaissance was made by Doug Stack and Ralph Mock of Chen and Associates, Inc. along the proposed road alignment. In addition, colored aerial photography at a scale of 1:15840 was available for our investigation.
Engineering geologic and geotechnical analysis of paleoseismic shaking using liquefaction effects: Field examples
The greatest impediments to the widespread acceptance of back-calculated ground motion characteristics from paleoliquefaction studies typically stem from three uncertainties: (1) the significance of changes in the geotechnical properties of post-liquefied sediments (e.g., "aging" and density changes), (2) the selection of appropriate geotechnical soil indices from individual paleoliquefaction sites, and (3) the methodology for integration of back-calculated results of strength of shaking from individual paleoliquefaction sites into a regional assessment of paleoseismic strength of shaking. Presented herein are two case studies that illustrate the methods outlined by Olson et al. [Engineering Geology, this issue] for addressing these uncertainties. The first case study is for a site near Memphis, Tennessee, wherein cone penetration test data from side-by-side locations, one of liquefaction and the other of no liquefaction, are used to readily discern that the influence of post-liquefaction "aging" and density changes on the measured in situ soil indices is minimal. In the second case study, 12 sites that are at scattered locations in the Wabash Valley and that exhibit paleoliquefaction features are analyzed. The features are first provisionally attributed to the Vincennes Earthquake, which occurred around 6100 years BP, and are used to illustrate our proposed approach for selecting representative soil indices of the liquefied sediments. These indices are used in back-calculating the strength of shaking at the individual sites, the results from which are then incorporated into a regional assessment of the moment magnitude, M, of the Vincennes Earthquake. The regional assessment validated the provisional assumption that the paleoliquefaction features at the scattered sites were induced by the Vincennes Earthquake, in the main, which was determined to have M ??? 7.5. The uncertainties and assumptions used in the assessment are discussed in detail. ?? 2004 Elsevier B.V. All rights reserved.
Engineering geology investigation, Game Creek-Cache Creek road corridor, Teton National Forest, Teton County, Wyoming
This report summarizes the results of an engineering geology investigation for the proposed Game Creek - Cache Creek Road Corridor, access to NCRA drill site. The purpose of the investigation was to provide geologic data so that the U.S. Forest Service and U.S. Geological Survey can jointly draft an Environmental Impact Statement. The location of the proposed road corridor is shown on Fig. 1. The general geologic conditions within the corridor are described and their anticipated impacts on the proposed road are discussed. The data and conclusions presented in this report are suitable for evaluating general impacts; however, additional detailed studies will be required for design purposes.
Landslides and engineering geology of the Seattle, Washington, area
This volume brings together case studies and summary papers describing the application of state-of-the-art engineering geologic methods to landslide hazard analysis for the Seattle, Washington, area. An introductory chapter provides a thorough description of the Quaternary and bedrock geology of Seattle. Nine additional chapters review the history of landslide mapping in Seattle, present case studies of individual landslides, describe the results of spatial assessments of landslide hazard, discuss hydrologic controls on landsliding, and outline an early warning system for rainfall-induced landslides.
Engineering geology as applied to highway construction
A geologic study of the site for a relocated segment of State Highway 93 northwest of Denver Colo., was made by by the Engineering Geology Branch of the U.S. Geological Survey as a demonstration of the applicability of geologic mapping to problems of highway construction. The relocated segment provides access to the Rocky Flats plant of the Atomic Energy Commission. The geologic conditions along five miles of the relocation route were examined. In most places apparently well-indurated sandstones of the Upper Cretaceous Fox Hills sandstone and Laramie formation can be excavated without using explosives. The intersection of a six foot thick coal seam in the roadbed in one proposed cut was predicted and removal and replacement with more suitable subgrade material was recommended. Near Marshall the alignment crosses three northeast-trending normal faults which do not adversely affect the highway. Clay minerals with expanding properties are present in some of the claystones of the Laramie, and special measures must be taken to ensure that ground water will not seep into them and cause swelling beneath the roadbed. Late Tertiary or Early Quaternary gravel cap pediments along the mountain front. Ground water issuing from seeps and springs found at the contact between these gravels and the underlying bedrock should be intercepted and removed from beneath the roadbed.
Engineering geology considerations for park planning, Antelope Island State Park, Davis County, Utah
Report : 00 - 1 In the mid-1980s, historically high levels of Great Salt Lake caused damage to park facilities on Antelope Island and destroyed the causeway linking the park to the mainland. Information on the engineering geology of Antelope Island can be used to improve park facilities and reduce the risk from geologic hazards and poor construction conditions. Certain characteristics of the geologic environment need to be considered in park planning . During wet cycles, Great Salt Lake may reach static levels of 4,217 feet (1,285.3 m), and wave- and wind-elevated levels locally may reach 6.5 feet (2 m) higher. A probabilistic assessment of the earthquake ground-shaking hazard along the Wasatch Front indicates that peak ground accelerations of approximately 0.20 to 0.30 g have a one-in-ten chance of being exceeded in 50 years on the island . A slope-failure hazard exists locally in colluvial and Lake Bonneville deposits, along the modern shore, and beneath cliffs. Flash-flood and debris-flow hazards exist on alluvial fans. Areas in the southern two-thirds of the island may have a relatively high potential for radon emission. Particular soil types on the island may be expansive, compressible, erodible, impermeable, or susceptible to liquefaction or hydrocompaction. The distribution of most geologic hazards can be defined, and many locations on the island have conditions suitable for construction. Lacustrine sand and gravel deposits are wide-spread and have engineering characteristics that are generally favorable for foundations. However, facilities and roads built close to the modern shoreline may be susceptible to lake flooding and erosion, slope failures, shallow ground water, and burial by active sand dunes. Well-graded (poorly sorted) alluvial-fan deposits are generally most suitable for wastewater disposal, although they may be subject to flooding or be underlain by low-permeability, fine-grained lacustrine deposits.
Engineering geology of the Northeast Corridor, Washington D.C., to Boston, Massachusetts: Bedrock geology
No abstract available.
Engineering geology of the Northeast Corridor, Washington, D.C. to Boston, Massachusetts: Coastal plain and surficial geology
No abstract available.
Preliminary geologic map of parts of Bristol quadrangle, Hartford, Litchfield, and New Haven counties, Connecticut, with preliminary engineering geologic interpretations
Explore the source record for details and available documents.
Field occurrences of liquefaction-induced features: A primer for engineering geologic analysis of paleoseismic shaking
Discussed in this paper are the factors that control the typical manifestations of liquefaction that are found in continental field settings. The factors are given mainly in terms of the local geologic field situation and the geotechnical properties there. A meaningful interpretation of liquefaction-based data for quantitative analysis of paleoseismic shaking requires understanding of both geologic and geotechnical roles in the mode of ground failure at a specific site. Recommendations are made for the size of the field area that must be searched for liquefaction effects, in order to develop adequate data for engineering geologic/geotechnical analyses of paleoseismicity. The areal extent must be based on an appreciation that the tectonic situation can cause seismically induced liquefaction effects to form in some locales, but not in others nearby, even for a strong earthquake in the region. Our guidelines for the conduct of the field search and preliminary analysis of the data relate to three issues for which liquefaction features are especially useful in answering: Has there been strong Holocene/latest Pleistocene shaking in the region? Where was the tectonic source? And what was the strength of shaking? Understanding of the various factors that control the manifestations of liquefaction effects, which we present in this paper, is essential for developing credible answers to these questions. ?? 2004 Elsvier B.V. All rights reserved.
Engineering-geology site appraisal of the Federal Capital Territory, Nigeria
The 7,700-km 2 -area Federal Capital Territory, Nigeria, is underlain by crystalline igneous and metamorphic rocks of Precambrian age. Sandstone and claystone of Cretaceous age overlie Precambrian rocks in the southwestern part of the Territory. Laterite caps many hills of Cretaceous rock, some hills of Precambrian rock, and crops out near stream banks in the east and northeast. The most conspicuous structural features are a broad “J”-shaped fold traversing the eastern and central part of the Territory and a north-trending shear zone along the eastern boundary. The soils of the Territory are lateritic and belong to the SW-SP-SM (Unified Soil Classification System) groups covering Precambrian migmatites gneisses and granites and the SC group covering Cretaceous sediments and Precambrian mica-rich schists. The average penetrometer shear strength of the soil is 3.11 bars. The engineering characteristics of the rocks are (1) medium- to high-strength massive and gneissic rock, (2) low-to medium-strength bedded rock, and (3) low-strength foliated and sheared rock. An area of at least 800 km 2 is free from apparent geological hazards and should be suitable for construction of a capital city, its environs and supporting facilities.