bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of test method and procedure on measurements of residual shear strength of bentonite from the Portuguese Bend landslide
Authors: Watry Stephen M. , Ehlig Perry L.
Published: May 2013

Palos Verdes Peninsula contains large landslides in areas that are otherwise desirable for residential development. The landslides can be developed providing the factor of safety is at least 1.5 or can be raised to 1.5 during development. The greatest uncertainty in the calculated factor of safety is the residual shear strength of bentonite that forms the bases of slides. The use of too high a shear strength inflates the calculated factor of safety and can result in landslide failure after development. Tests by various investigators yield a wide range of residual shear strengths for bentonite samples from Palos Verdes Peninsula. Most residual friction angles (4φr) range between 6° and 14° with one lower value (3.5°) and several higher values reported. Residual cohesions (Cr) range mostly between 0 and 36 kPa (0 to 750 lb/ft2). Data for various bentonite samples from Palos Verdes Peninsula indicate they have similar compositions and Atterberg limits. Calcium montmorillonite is the principal clay mineral; the liquid limit is generally between 80% and 110% with the plasticity index between 40% and 70%. The data suggest that much of the reported variation in residual shear strength is the result of differences in sample preparation, testing methods, and interpretation of results rather than true differences in strength. Bulk samples of bentonite from the base of the Portuguese Bend landslide were remolded and tested by conventional direct shear, long sample direct shear, and ring shear devices to determine the effect of testing method on residual shear strength measurements. The three devices gave similar results—for conventional direct shear, φr = 6.9° and Cr = 33.0 kPa (690 lb/ft2); for long sample shear, tyr = 6.8° and Cr = 23.8 kPa (497 lb/ft2); for ring shear, tyr = 6.7° and Cr = 7.2 kPa (150 lb/ft2). Back calculations indicate the ring shear results most closely simulate the residual strength along the base of the Portuguese Bend landslide. For all those devices, the residual shear envelope is a curve whose slope reaches an asymptote near a confining pressure of 200 kPa (approximately 4,000 lb/ft2). Reported φr angles are commonly too high because samples were not tested at sufficient confining pressure to define the asymptote and a best fit straight line was drawn through the data points.
Evaluation of viscoplastic slope movement based on triaxial tests
Authors: Wong Wylie W.-H. , Ho Carlton L. , Iverson Richard M. , Hovind Cynthia L.
Published: May 2013

Viscoplastic soil parameters are used in a nonlinear viscoplastic constitutive model to predict time-dependent displacement of slow-moving landslides. The viscoplastic material parameters are determined by a novel method that uses a standard triaxial apparatus. This method employs data obtained from consolidated drained triaxial tests and consolidated drained stress-controlled strain-rate tests. The methodology was applied to undisturbed samples from the Minor Creek landslide in the Franciscan Terrane of northern California. Viscoplastic parameters determined from the laboratory tests were combined with boring log data to calculate the landslide’s vertical velocity profile. This profile provided a reasonable match to a measured velocity profile obtained from repetitive inclinometer surveys.
Stability of slopes
Authors: Michalowski Radoslaw L.
Published: May 2013

Traditional analyses of earth slope stability are based on equilibrium considerations of “slices” into which the collapsing soil mass is divided. Such analyses require some static assumptions so that the system of equilibrium equations becomes determinate. It is proposed that the kinematics-based limit analysis be used to calculate the stability (factor of safety or the critical height), rather than using the limit equilibrium technique with arbitrary static assumptions (such as, for instance, inclination of forces between slices). The method described is straightforward, the analysis has a clear mechanical interpretation, and it stands on its own as a means of performing stability analyses for earth slopes. The method proposed, when used with identical failure mechanisms as in traditional slice methods, can be used to assess the static assumptions used in these conventional methods. It can be argued that all solutions using conventional slice methods can be bound by a rigorous upper bound solution and another approximate solution, both presented in this paper. Traditional solutions which fall beyond the range indicated lead to unrealistic consequences when interpreted in view of the collapse mechanism.

A convenient technique for including the influence of the pore pressure on stability of slopes is shown, and results of critical height calculations for homogeneous slopes are presented.
Geology education in the U.S. Army
Authors: Jens John C. , Stevens M. Merrill
Published: May 2013

The U.S. Army trains soldiers in geology under the guise of related topics. Thus, instructional responsibilities are disjointed.

The army considers geologic matters to be the responsibility of Engineer officers. Familiarization of topographic requirements and construction practices, both military and civil, is given in the Engineer Officer Basic Course, with specific concepts included in the Engineer Officer Advanced Course. Officers wanting more depth in topographic matters take the Mapping, Charting, and Geodesy Officers Course that emphasizes terrain analysis.

Enlisted personnel have more direct contact with geology. Construction materials specialists and quarry operations specialists receive instruction in rock identification and properties about quarrying and construction. On the topographic side, Basic Terrain Analysis teaches mineral and rock identification—weathering and soils are the targeted tasks. Sergeants learn more advanced geology concepts within an imagery analysis and interpretation block of classes in the Advanced Terrain Analysis Course.

Warrant officers, normally selected from the enlisted ranks, provide technical expertise in terrain analysis. Although they receive no formal training, the competitive selection process generally chooses those with the most extensive computer knowledge and field experience in terrain analysis. Geology skills per se are not a criterion.

The Topographic Engineering Center provides, when needed, a two-week intensive interdisciplinary imagery analysis and interpretation short course, which is primarily for federal agencies.
Location of sites for airstrips in North Greenland
Authors: Krinsley Daniel B.
Published: May 2013

Engineering geological investigations of North Greenland for the purpose of locating sites suitable for airstrips were conducted by earth scientists of the U.S. Geological Survey, Air Force Cambridge Research Laboratories, and the U.S. Army Corps of Engineers in 1956–1960. Potential sites that were approximately 5,000 ft (1,524 m) long with clear approaches, delineated through photogeologic studies and aerial reconnaissance, received on-site examination of their relief, frost features, drainage, depth to permafrost, soil composition, strength, and other engineering properties. The resulting favorable sites that required only a minimal amount of surface modification were selected for the test landings of heavy aircraft such as the C-124 and C-130. Successful landings were made at Bronlunds Fjord in 1957, at Polaris Promontory in 1959, and at Centrum Lake in 1960.

Soils are strong enough to support heavy aircraft at these tested sites except during the spring thaw in June and July. Permafrost conditions at the North Greenland sites do not impose severe restrictions on minor grading and light construction if the surficial materials on and immediately adjacent to the airstrips are not extensively removed.
Selected military geology programs in the Arctic, 1950–1970
Authors: DeGoes Louis , Neal James T.
Published: May 2013

The military environment of the post–World War II years was dominated by the principal threat of air and missile attacks over polar routes between North America and the former Soviet Union. The extremities of the arctic environment demanded unique adaptations to normal military operations, which provided military and engineering geologists an opportunity to exercise a broad range of technical applications. New knowledge and skills in ice physics and engineering, glaciology, arctic geomorphology, meteorology, oceanography, and permafrost engineering were all relevant, often requiring on-the-job learning. Such adaptability could be needed in the future and would once again challenge military geologists.
Hydrogeological assessments of United Nations bases in Bosnia Hercegovina
Authors: Nathanail C. Paul
Published: May 2013

The need to ensure reliable and secure water supply at United Nations bases in Bosnia Hercegovina led to a hydrogeological and water supply reconnaissance (recce) of each base to determine the feasibility of constructing boreholes within the base perimeter. The recce was conducted under full security measures at a time when the armed conflict in central Bosnia was at its fiercest. Fieldwork was severely limited by the ongoing war. Facilities such as generators, vehicle repair yards, and latrines excluded certain areas within the perimeter wire and restricted where boreholes could be sited.

Despite the disruption to the infrastructure and government caused by several years of conflict, some site-specific information was obtained. All sites were assessed as having a good potential for ground water. Preliminary well designs were determined. These were accepted and well drillers were deployed to Vitez, Gornji Vakuf, and Tomislavgrad. Following the deployment of the drillers to Bosnia, the author was able to use his experience of the ground to advise during the well construction phase.

The author also provided advice on slope stability along parts of the main supply route (MSR) near Prozor and on the location of suitable borrow pits for material to maintain the surface of the MSR near Redoubt Camp.

The participation of the Royal Engineer Specialist Advice Team geologist in Operation Grapple continued the tradition of geological input into recent major British army operations such as those in the Falklands, the Gulf, and northern Iraq.
Military geology in support of nation assistance exercises in Central and South America
Authors: Knowles Robert B.
Published: May 2013

Engineer construction training exercises throughout Central and South America have provided U.S. soldiers with construction experience and aided the host nation by developing infrastructure. Roads, airfields, bridges, schools, hospitals, and water wells are constructed in remote areas with maximum use of local materials. Military geologists support construction by locating potential sources of aggregate, evaluating suitability of materials for road metal and fill, designing roadcuts, developing quarries, and evaluating geologic hazards that may affect the construction effort.

In northern Honduras, excavation problems in a karstic limestone of the Mesozoic Yojoa Group delayed completion of a mountain road. Clay-filled solution cavities disrupted the blasting operation, jeopardizing the completion of the project. Geologists recommended rerouting the road through a rippable schist. Although longer, the new road was completed on time.

In southern Honduras the lack of a suitable aggregate for a new airfield required a thorough geologic reconnaissance for new sources. Local ignimbrites were unsuitable due to their low compressive strength. Rhyolite and andesite from nearby volcanic erosional remnants were evaluated for their suitability. A quarry was subsequently developed and provided the aggregate needed to complete the project.

In the Oriente of Ecuador a scarcity of suitable construction materials and unstable slopes created difficult conditions for a road and bridge construction project. Roadcuts into alternating layers of shale and limestone of the Cretaceous Lower Napo Formation created unstable slope conditions. Military geologists recommended new sources of aggregate and advised engineers on slope stability. Local construction methods were adopted to overcome these conditions.
American geologists at war
Authors: Pittman Walter E.
Published: May 2013

During World War I the combatants committed the total resources of their nations in this first great total war. This came to include geological expertise. The original use of geologists on the battlefield was to locate potable water supplies; later employments were an outgrowth of the stalemate on the battlefield. Mine warfare quickly developed as the belligerents tried to tunnel under the formidable trench systems. Geologists in uniform provided assistance for these efforts and came to be valued for their professional advice.

More uses were quickly found for geologists. Trafficability studies of terrain, predictions of stream and river heights, sources of construction materials, and location of water supplies were important missions. Later, as both sides learned to communicate through ground-loop telephony, ground-conductivity studies became important.

By the time the United States entered the war in 1917, mine warfare had been neutralized by countermining, and no further active mine operations were undertaken. The U.S. Army sent 10 geologists (three more were en route on November 11, 1918), a mining regiment, and a water supply regiment of engineers to support the American Expeditionary Force. Most geologic work was in terrain studies and in mapping, water supply, and soil trafficability studies. In the United States, other geologists worked to discover sources of scarce raw materials. American geologists generally were disappointed, however, at the contributions they were able to make to the war effort, whether in France or America.
Geology and military operations, 1800–1960
Authors: Kiersch George A. , Underwood James R.
Published: May 2013

The first recorded use of terrain analysis was in 1813 during the Napoleonic Wars, and in most major military operations since that time, geologic counsel and assessment have played important roles. Intelligent use of the terrain of the battlefield, movement of supplies and personnel, and the procurement of adequate supplies of water and of construction materials all have relied on an understanding and application of geologic principles.

During the 19th century, as the value of geologic insight came to be recognized, books on military geology appeared as did basic courses in geology at military academies in the United States and abroad. Beginning in World War I, vital geologic data were placed on increasingly sophisticated specialized terrain maps and used both tactically and strategically. Successful military mining beneath enemy fortifications in World War I required an understanding of subsurface geology, including hydrogeology. And in the 1940s and 1950s, geologic principles were applied on an unprecedented scale to the construction of massive underground installations. Moreover, in the 1950s, these principles, applied in a massive research effort, resulted in the ability to distinguish the release of energy by an underground nuclear test from that produced by a natural seismic event.

As weapons and defenses against them continue to evolve, geoscience and geoscientists will play an increasingly important role in military planning and operations in diverse and challenging environments worldwide.
Military Geology Branch of the U.S. Geological Survey from 1945 to 1972
Authors: Terman Maurice J.
Published: May 2013

After World War II, the Military Geology Unit of the U.S. Geological Survey was transformed into the Military Geology Branch, which recruited about 150 younger scientists over time to continue the compilation of terrain intelligence on a global scale. Source materials were the scientific journals, books, maps, and photographs available in the Washington area, and most topics were presented on maps accompanied by succinct tables and short narrative texts. The following principal administrative units and research programs evolved: (1) Strategic Studies Section (1945–1972; funded by the U.S. Army Corps of Engineers and later by the Defense Intelligence Agency) was the major production unit. Its principal responsibility was to contribute to the comprehensive small-scale National Intelligence Surveys Program. Another significant section effort included the Pacific Engineer Intelligence Program, which involved the compilation in Washington of seven series of 1:250,000-scale thematic maps for most of Southeast Asia. (2) Pacific Field Program (1945–1962; Corps of Engineers) was a research and mapping program in areas formerly occupied by Japan. (3) Alaska Terrain and Permafrost Section (1947–1965; Corps of Engineers and U.S. Geological Survey) conducted field studies on surficial geology and permafrost phenomena in Alaska and other Arctic areas and compiled reports with maps and engineering interpretations, most at a 1:250,000 scale of Alaska. (4) European Field Program, principally undertaken by the U.S.G.S. Team (Europe) (1953–1964; U.S. Army Europe), published a series of 24 1:250,000-scale maps of military engineering geology for western Germany and 131 1:100,000-scale maps of cross-country movement for all of Germany, and the team served as a consultant. (5) Austere Landing-Site Program (1956–1970; U.S. Air Force) compiled large-scale studies on arid lands, both inside and outside the United States and on Arctic ice-free land. (6) Special Intelligence Element (established 1959; Corps of Engineers and Defense Intelligence Agency) continues to serve as geoscientific consultants to the special intelligence community. (7) Nuclear-Test Detection Program (principally 1962–1972; Advanced Research Projects Agency) compiled studies assisting in the interpretation of global seismic signals, particularly the five-volume 1:5,000,000-scale Atlas of Asia and Eastern Europe.
Quantifying terrain fabric in digital elevation models
Authors: Guth Peter L.
Published: May 2013

Eigenvector analysis of a topographic landform reveals a directional fabric consisting of surface roughness or slope, organization or fabric strength, and preferred orientation. This analysis uses a digital elevation model (DEM) to compute slope and aspect at all points in a region and uses those values to define the normal surface. Standard techniques contour the distributions, extract eigenvectors and eigenvalues from the matrix of the sum of cross products of the directional cosines, and compute eigenvalue ratios. The terrain fabric at a point depends on the size of the region used for the computation and reveals different scales over which directional fabrics operate. With large-scale DEMs, the directional fabric varies in a systematic manner and proves relatively insensitive to the horizontal resolution of the DEM or its quality and creation method. Quantitative measurement of terrain fabric belongs in all studies of terrain analysis and geomorphometry.
Unsurfaced road investigation and management plan, Fort Leonard Wood, Missouri
Authors: Isaacson Jon B. , Hurst A. Elaina , Miller Danny L. , Albertson Paul E.
Published: May 2013

Unsurfaced roads, common throughout both private and public sectors, are the source of engineering, economic, and ecological concerns. The U.S. Army currently maintains a large number of unsurfaced roads on its training and testing installations. These road networks must be maintained in a safe and serviceable condition to sustain training and testing requirements. Fort Leonard Wood’s (FLW) road network was examined to identify present problems and future engineer training requirements so that a proper maintenance plan could be recommended. Standard U.S. Army methods were used. A road management system was developed using a dynamic digital database of road conditions linked to the FLW Geographic Information System (GIS). The field data, the extent of road distresses and severity level measurements, were used to determine the unsurfaced road condition index (URCI). A repair budget was estimated for road segments with a URCI value below an established threshold. GIS analyses correlated URCI values to physical and operational conditions. Well-graded soils with a low plastic index were correlated to high URCI values. Operations data were examined to identify types of use, requested maintenance, and the resulting road condition. URCI values were higher for frequently traveled and maintained roads. Continuation of current reductions in maintenance will result in higher repair costs and possible road closures. Road rehabilitation to accommodate future traffic volume and increased vehicle loads will require proper selection of geometric design parameters, aggregate type, gradation, and layer thickness.
Geology without borders
Authors: Dunbar Joseph B. , Wakeley Lillian D. , Miller S. Paul , Swartzel Stanley M.
Published: May 2013

Research by the U.S. Army Corps of Engineers at numerous military facilities has shown that a regional geologic approach is the key to cost-effective risk assessment and environmental remediation. This approach addresses the needs of the facility by placing it directly in the larger framework of the land, water, and the people off post who comprise potential contaminant receptors. Application of a regional geologic framework to a large military facility requires extensive research and focused study to establish the overall picture.

A regional geologic and geomorphic model was developed for the Aberdeen Proving Ground (APG), located in the headwaters of Chesapeake Bay near Aberdeen, Maryland, USA. Regional geologic information and interpretation of data from over 2000 geologic and water well borings indicate that APG is situated upon Pleistocene terraces of the ancestral Susquehanna River, which unconformably overlie Cretaceous unconsolidated sediments. Pleistocene terraces represent estuarine and fluvial filling of an earlier manifestation of Chesapeake Bay during interglacial periods of high sea level during the past 1.5 m.y. During episodes of low sea level, corresponding to glacial maxima, the Susquehanna River downcut into Pleistocene and Cretaceous deposits. The remnants of at least three and possibly four separate filling cycles, ranging from middle Wisconsin to early Pleistocene in age (youngest to oldest), are present at APG. The geologic and geomorphic model of APG is being used to define aquifer limits and to assess the movement of groundwater for potential impacts to public drinking water supplies on the Aberdeen Peninsula and to Chesapeake Bay.
Terrain evaluation for peacekeeping with examples from Bosnia Herzegovina
Authors: Nathanail C. Paul
Published: May 2013

Geology has influenced military commanders and the outcome of military operations since ancient times. Terrain evaluation was developed in the 1960s and has benefited greatly from recent developments in GIS (geographic information systems). Peacekeeping operations are increasingly becoming a component of armed forces workload. Geologic support based on terrain evaluation principles was provided to the UN and NATO during peacekeeping and humanitarian relief operations in Bosnia Herzegovina. This included assessments of slope stability, seismic hazard, flood risk, groundwater potential, and construction materials.

The role of the geologist advising military commanders during peace support operations essentially becomes a hybrid of those roles of military geologists and conventional civilian engineering geologists. As ever, training in the engineering operations of the “client” is essential to delivering a successful product—usually defined as an approximate answer within a very limited time frame rather than a “good” answer late.
A three-phase program of investigation for site selection and development
Authors: Caggiano J.A.
Published: May 2013

The selection of a site and the development of geologic and seismic design parameters may be facilitated through the use of a three-phase program of investigation. This program is cost effective and expedites management decisions that benefit from current relevant geologic information. A resource review and regional reconnaissance during Phase I serve to eliminate areas of low potential, to focus on favorable areas, and to identify possible problems that may require further study. Preliminary estimates of certain design parameters during Phase I may be used to initiate contract negotiations with a plant supplier. Candidate sites and associated problems can then be examined through analysis of large-scale maps and imagery, preliminary geologic mapping, and subsurface investigation during Phase II. Phase II may lead to preparation of an Early Site Review Report (ESRR) for submission to the Nuclear Regulatory Commission (NRC). A Phase III investigation leading to the preparation of a Preliminary Safety AnalysisrReport (PSAR) can be performed concurrently or sequentially on any or all candidate sites recommended at the conclusion of Phase III.

This approach is illustrated with examples from Spain and Iran showing how such a program assists in selection and study of possible sites.
Application of microfacies analysis to the identification of stratigraphic marker beds in the Tertiary strata of northern Puerto Rico
Authors: Osborne Robert H. , Junge Walter R. , Seiglie George A.
Published: May 2013

Microfacies analysis is a mature and sophisticated set of procedures for solving a variety of stratigraphic problems. One of the most important of these problems is the identification and definition of surfaces for stratigraphic correlation. There is virtually no end to the list of potential correlative surfaces that can be defined by microfacies analysis, particularly when used in conjunction with available mathematical techniques for the quantification of geologic data. Such procedures are particularly useful in stratigraphic units characterized by complex fades relationships, such as reef-associated paleoenviron-ments. The utility of microfacies analysis in evaluating potential sites for nuclear power plants and other engineered structures is exemplified by studies performed in conjunction with the NORCO-NP-1 nuclear power plant site in northern Puerto Rico. The definition of three microfacies (Globigerinidea, Nummulites cojimarensis, and A mphistegina spp., in ascending order) within the Quebradillas Limestone (Tertiary) at the NORCO-NP-1 nuclear power plant site demonstrated that two surfaces along which important natural gamma ray peaks occur are strati-graphically controlled rather than being controlled by dislocation surfaces, unconformities, jointing, or karstification. This was accomplished by showing that the surfaces defined by the gamma ray peaks are parallel or subparallel to two deposi-tional surfaces, the base and top of the N. cojimarensis microfacies, within the apparently massive carbonates of the Quebradillas Limestone.
Trenching as an exploratory method
Authors: Hatheway Allen W. , Beach Leighton F.
Published: May 2013

The critical nature of siting nuclear power plants has led to increased emphasis on exploratory trenching. Trenching is the most definitive of all subsurface exploratory methods; it permits inspection of a continuous geologic section by both geologists and regulatory authorities and makes possible the preparation of a graphic log that delineates both obvious and subtle geologic features. About one of every two nuclear plant licensing efforts utilizes exploratory trenching. Many geologic hazards, such as "capable" faults, can be detected from trench exposures; they may otherwise remain undetected.

Trenches must be judiciously located, survey-controlled, excavated safely and adequately shored, logged in detail, and properly diagnosed. Useful techniques of trench logging include thorough cleaning of the trench walls, teamwork between geologist and recorder, logging against a carefully surveyed baseline and vertical reference grid, and panoramic photography. Soils, including paleosols, and glacial and glaciofluvial deposits present some of the most difficult media to log.

Trench logs must be thoroughly interpreted and correlated so that they document the geologic conditions governing suitability of the site. Age-determination techniques utilized in exploratory trenching include petrographic analyses, quartz inclusion studies, clay mineralogic analyses, and radiometric methods.
Seismicity of the central United States
Authors: Nuttli Otto W.
Published: May 2013

The combination of moderate seismic activity, sparsity of seismograph stations and relatively low density of population makes it difficult to assign quantitative seismicity values to most of the central United States. In the New Madrid seismic zone, where the level of seismic activity is higher and the number of seismograph stations is more adequate, one can delineate the active fault zone and determine a magnitude-recurrence relation. These capabilities will be extended to other seismic zones as arrays of seismographs are installed for recording microearthquakes, which will give information on fault delineation, focal mechanism, and magnitude frequency. Only after such information is available will we be able to make positive statements relating seismic activity to specific geologic features.

The seismicity data suggest that earthquakes that occur outside the recognized seismic zones or major structural features will have a maximum body-wave magnitude mb of 5.5 and that this maximum value will occur only infrequently. Experience shows that if these relatively minor earthquakes are only a few kilometres deep they may have an epicentral intensity at least as large as VII (observed for an earthquake of mb = 3.8), but their magnitude and area of perceptibility will be small. With the exception of the New Madrid seismic zone and possibly the Wabash Valley seismic zone, a conservatively reasonable value for the maximum body-wave magnitude to be expected in the major seismic and structural zones of the central United States is 6.5. For the New Madrid seismic zone an earthquake of body-wave magnitude equivalent to that of a great earthquake (mb = 7.5) can be expected, on the basis of what has already been experienced in 1811-1812.

Because of low anelastic attenuation, the earthquakes in the central United States are felt and cause damage over much wider areas than earthquakes of comparable magnitude in the western United States. Further consequences are that the ground shaking has a longer duration and that the ground-motion spectrum shifts at the larger distances to lower frequencies, which results in relatively low ground acceleration for relatively large ground displacements and a greater effect on high-rise than low-rise structures.
Seismicity of the western United States
Authors: Bolt Bruce A.
Published: May 2013

A critical review is given of the present status of the record of earthquakes in the western United States. Special field studies for siting of nuclear reactors and other major structures have brought to light major modifications and revisions of some earlier inferences on the intensity and fault location of historical earthquakes. For example, the hypocenters of the Washington State earthquake of December 14, 1872, and the Lompoc, California, earthquake of November 4, 1927, have recently been redetermined. Presentation and retrieval of both modern and historical seismicity records are still not optimum, with various errors and inconsistencies—some introduced by computer processing.

Increased density of seismographic networks is providing sharper resolution in seismicity mapping. In northern California the pattern of widespread minor seismicity has been defined for the first time; earthquake foci in the Humboldt County region are concentrated in two crustal levels, 0 to 10 km and 18 to 20 km. Use of ocean-bottom seismographs is improving knowledge of the offshore seismicity pattern. Seismotectonic properties of northwestern California, Puget Sound (Washington), and the intermountain seismic belt are now emerging.
Toronto’s subsurface geology
Authors: White Owen L.
Published: May 2013

The subsurface geology in the Toronto area, in which much underground con-struction has taken place in the past 30 years, is, in general, fairly simple, consisting of almost flat-lying Ordovician sediments overlaid by a variable thickness of Quater-nary drift deposits.

The Ordovician rocks provide an interbedded sequence of shales, siltstones and limestones; and the Quaternary deposits, which range in age from Illinoian to Late Wisconsinan, consist of several tills interbedded with water-bearing sands and lacustrine clays and silts.

Construction difficulties arising from the local geological conditions are not great, but unexpected encounters with excess ground water do occur. The presence in the bedrock of high horizontal stresses at shallow depths can cause difficulties, especially to the completed structure, unless the stress condition is recognized, designs are modified, and construction procedures are adapted to the unusual stress environment.
Effects of geology on the development of Edmonton, Alberta, Canada
Authors: Rutter N. W. , Thomson S.
Published: May 2013

The City of Edmonton is underlaid by a thick sequence of Quatenary glacial deposits overlying gently dipping late Cretaceous clastic sediments. The Quaternary stratigraphy consists of Saskatchewan gravels and sands, two continental till deposits (upper and lower till) separated in places by Tofield sand, all overlaid by Glacial Lake Edmonton sediments. Underground activity has centered on tunneling for sanitary and storm sewer systems and, more recently, for part of Edmonton’s Light Rapid Transit system. Nearly all tunneling is in the competent till or bedrock. Other underground activity took place around the turn of the century when coal mining shafts and adits were constructed. Surface subsidence continues today and has to be considered when planning. The greatest hazard in the development of Edmonton is natural landslides that occur along river banks and man-made slopes. Major failures take place mainly in bedrock with small slips in the Lake Edmonton sediments.
Field-based computational techniques for predicting subsidence due to fluid withdrawal
Authors: Helm Donald C.
Published: May 2013

Choice of a predictive technique for land subsidence is based on the availability of appropriate field data. If only the depth and thickness of compressible beds can be estimated, a simple hand calculation is available as a predictive technique and for many purposes is adequate. An example of such a technique uses Schatz, Kasameyer, and Cheney's depth-porosity model. Their depth-porosity model for reservoir compaction is modified in the present paper and is combined with a modified form of Geertsma's nucleus of strain model to form a single predictive technique. The nucleus of strain model accounts for attenuation of vertical movement through the overburden. Based on this combined model, predictions of ultimate vertical subsidence are made at eleven specified locations. At five of these sites in California, Texas, and New Zealand, these predictions are compared to measured subsidence. Agreement between predicted and observed subsidence is good.

If field measurements of water-level fluctuations and the resulting time-dependent compression and expansion of geologic strata are locally available, use of a more refined predictive technique is justified. An example of such a technique uses Tolman and Poland's aquitard-drainage model in conjunction with a field-based method of parameter evaluation (such as Riley's field-based method of estimating specific storage and vertical hydraulic conductivity). Tolman and Poland's conceptual model and Riley's parameter evaluation method have been combined with Helm's one-dimensional finite difference computational scheme to form a powerful time-dependent predictive technique. This technique has been field verified successfully at more than two dozen sites in California and Texas. Use of such a computer code allows prediction of observed time lags in nonlinear compression and expansion of layered sedimentary materials in response to arbitrary sequences of rising and falling water levels.
Organic soil subsidence
Authors: Stephens John C. , Allen Leon H. , Chen Ellen
Published: May 2013

Organic soil subsidence occurs mainly with drainage and development of peat for agriculture. Subsidence occurs either from densification (loss of buoyancy, shrinkage, and compaction) or from actual loss of mass (biological oxidation, burning, hydrolysis and leaching, erosion, and mining). Densification usully occurs soon after drainage is established. Slow, continuous loss of mass is due mainly to biological oxidation. Erosion is minor except in specific sites. Mining losses vary greatly and depend upon direct removal of the materials.

Subsidence rates are determined mainly by type of peat, depth to water table, and temperature. Subsidence losses have been carefully measured in several locations (e.g., the Florida Everglades), and predictions of future subsidence developed in 1950 have proved reliable.

Peat drainage and subsidence have several consequences: loss of plant rooting depth where the substrate is unfavorable (stony, acidic, saline), increased pumping for drainage, instability of roads and other structures, increase in nutrient outflows, colder surface temperature during winter nights, and increase of CO2 flux to the global atmosphere

The water table for organic soils should be held as high as crop and field conditions allow to reduce subsidence.

Computer models offer methods for refining oxidation rate processes and prediction of subsidence losses where adequate calibration data are available. Remote sensing offers a method of assessing organic soil area and drainage changes. These new technologies should improve our assessment, and guide our management, of organic soil resources.
Compound landslides
Authors: Cronin Vincent S.
Published: May 2013

Large host landslides commonly encompass smaller, secondary landslides; hence the term “compound landslide.” Secondary landslides differ significantly from their host landslide in that secondary slides (1) have smaller volume; (2) often have greater surface exposure; (3) are more readily saturated by water infiltration; (4) require a smaller driving force to initiate movement; (5) have greater frequency of movement; and (6) their capacity for movement can be either independent of the host and other adjacent secondary landslides, or induced by adjacent landslides. Multilevel flow systems (perched water tables) commonly form within compound landslides due to the relatively low permeability of slip-surface gouge, which may slow recharge from the overlying secondary landslides to the host landslide. Movement-inducing pore-fluid pressures can often be reached more rapidly in secondary landslides. Controlled sources of water, for example, from irrigation and septic waste-water injection systems, can supplement vastly natural recharge from rainfall, artificially maintaining saturation in near-surface secondary landslides.

The progressive movement of a host landslide can generate a family of precursive failure surfaces in the landslide’s interior that can coalesce to form secondary landslides. Evolution of local topography contributes to the morphology and slip direction of secondary landslides to the extent that stress trajectories within a host landslide are perturbed by changes in the shape of the ground surface; for example, increased slope gradient along a landslide’s toe is a common cause of secondary landsliding. The non-plane strain nature of compound landslides, exemplified by the complex interactions between host and secondary landslides, often precludes the meaningful application of general, plane strain, mechanical models in assessing the hazard potential of a specific compound landslide. Rote stability analyses of compound landslides based upon assumed homogeneous, isotropic, linear-elastic behavior throughout the slide prism fail to consider the intrinsically more unstable (and thus more hazardous) secondary landslides.

Geologists involved in landslide exploration must be aware of the characteristics of compound landsliding; those involved in mitigation must consider the hydrologic and dynamic implications of secondary landsliding in order to conduct the requisite field investigations and make appropriate design recommendations, which must be individu-ally suited to each compound landslide.
Differentiation between normal residence performance and landslide-related distress in the evaluation and treatment of slope instability in southern California
Authors: Robertson Hugh S. , Hollingsworth Robert A.
Published: May 2013

The evaluation and repair of hillside properties damaged by slope instability presents a challenging problem for the geotechnical professional. An increasing number of residential distress evaluations are being requested by homeowner insurance companies to resolve earth-movement claims. Early recognition of instability is essential to the successful mitigation of the hazard. Thorough observation of structural distress, experience, and an understanding of construction are needed to differentiate typical distress from subtle distress associated with the initiation of slope instability. Other soil-related processes cause distress similar in appearance to major slope movement, and complicate recognition of an impending hazard.

Property-line limitations and reluctant neighbors hamper site and neighborhood reconnaissance. High costs and physical constraints limit the subsurface exploration, which is critical to determining the mechanics of movement. Conventional exploration techniques are aided by modern instrumentation and detailed site monitoring to define probable causes. Selection of reasonable repair methods and stabilization devices de-pends on the limits of the failing mass and whether instability is associated with failure along a predetermined defect or through an inherently weak mass. Continued monitor-ing from recognition through stabilization helps verify the causes of instability, the design scheme, and the success of the treatment. Repairs are effective if the factor of safety is sufficiently increased by common and economical construction techniques in a timely manner.
Infectious mediastinal lymphadenopathy after repeated transbronchial needle aspiration
Authors: Hiraishi Yoshihisa , Goto Yasushi , Ohishi Nobuya , Nagase Takahide
Published: May 2013

A man in his 70s was diagnosed with squamous cell carcinoma (cT1aN2M0) by repeated transbronchial needle aspirations (one conventional and one using endobronchial ultrasonography) of the subcarinal lymph node. Shortly after the initiation of chemoradiotherapy, he began to have chest pain with a high fever. CT showed only subcarinal lymph node swelling. Treatment with several antibiotics was started, and his fever decreased gradually. Chest CT showed shrinking of the subcarinal lymph node, and a diagnosis of infectious lymphadenopathy was made. Infectious lymphadenopathy can be difficult to diagnose because the symptoms are often non-specific and CT findings are not useful in differentiating tumour growth.
Attitudes of general practitioners to screening for cystic fibrosis
Authors: Mennie M , Campbell H , Liston W A , Brock D J H
Published: May 2013

Objective To ascertain the views of general practitioners (GPs) about screening for cystic fibrosis. To find out whether and under what conditions they might play a part in the delivery of such programmes.

Setting All GP practices within the Lothian Health Board area.

Methods A self administered questionnaire was sent to each of the 532 GPs in the area.

Results 334 (63%) GPs participated in the study. Only 23% of these claimed to have no professional or personal experience of the disorder. 77% of GPs were aware of the existence of a programme of antenatal screening for cystic fibrosis (CF), which had been running in Edinburgh for the past six years, with only 2% unfavourably disposed to it. However, when asked to rank CF screening against antenatal screening for spina bifida and Down's syndrome, or cervical and breast screening, 55% gave it the lowest priority. There was fairly equal support for the screening site being an antenatal clinic, a genetic centre, a family planning clinic, or a GP surgery, but little enthusiasm for programmes in schools or the workplace. Surprisingly, only 13% of GPs thought that screening should be offered to those with a negative family history of the disorder. Although the idea of involvement in screening was favoured, GPs claimed that any aspect of delivery that they undertook would need to be supported. There were no significant differences between the responses of fundholding GPs and non-fundholders.

Conclusions The low ranking by GPs of CF screening against other programmes, together with the need for support if they were to be involved, suggests that it is currently impractical to move the programme from its existing site in antenatal clinics.
Breast cancer in East Anglia: the impact of the breast screening programme on stage at diagnosis
Authors: McCann J , Stockton D , Day N
Published: May 2013

Objectives To assess the impact of the National Health Service breast screening programme on overall and stage-specific incidence of breast cancer in East Anglia; also, to predict the magnitude of the screening induced reduction in breast cancer mortality.

Setting Women resident in East Anglia aged 50–69, diagnosed between 1976 and 1995.

Methods Comparison of numbers and incidence of breast cancer by age, stage, and mode of detection; investigation of relative contributions of advanced (stages II, III, and IV) cancers to total incidence by detection mode; estimation of the reduction in advanced cancer incidence.

Results There has been a large increase in early stage incidence in the age group 50–64 targeted by the screening programme. By 1995, the estimated decrease in advanced cancer incidence was between 7 and 19%. In 1995, of all breast cancers arising in the age group 50–69 years, 33% were screen detected, 27% were interval cancers, 15% were in non-attenders, 9% were in lapsed attenders, 7% occurred before invitation, and 4% arose in women outside the birth year range for invitation. Of the advanced cancers diagnosed in 1995, 31% were interval cancers, 20% were screen detected, 19% were in non-attenders, 12% were in lapsed attenders, 8% occurred before invitation, and 4% presented in women outside the birth year range for invitation.

Conclusions Screening has brought about a large increase in detection of early stage cancers. This increase has not yet been fully matched by a corresponding deficit in advanced cancers, possibly because the full effect of screening has not yet been achieved. Reducing the proportion of interval cancers is necessary to increase the effect of screening on mortality.