Late Holocene relative sea-level changes and the earthquake deformation cycle around upper Cook Inlet,Alaska

Multiple peat-silt couplets preserved in tidal marsh sediment sequences suggest that numerous great plate boundary earthquakes caused the coast around Cook Inlet, Alaska, to subside over the past 3500 years. Field and laboratory analyses of the two youngest couplets record the well-documented earthquake of AD 1964 and the penultimate one, approximately 850 cal yr BP. Diatom assemblages from a range of modern day estuarine environments from tidal flat through salt marsh to acidic bog produce quantitative diatom transfer function models for elevation reconstructions based on fossil samples. Only nine out of 124 fossil assemblages analysed, including previously published data for the AD 1964 earthquake, have a poor modern analogue. Calibration of fossil samples indicate co-seismic subsidence of 1.50±0.32 m for AD 1964, similar to measurements taken after the earthquake, and 1.45±0.34 m for the ∼850 cal yr BP earthquake. Elevation standard errors for individual fossil samples range from ∼0.08 m in peat layers to ∼0.35 m in silt units. Lack of a chronology within fossil silt units prevents identification of changes in the rate of recovery and land uplift between the post-seismic and inter-seismic periods. However, preservation of multiple peat-silt couplets indicates no net emergence over multiple earthquake cycles. Glacio-isostatic movements from Little Ice Age glacier advance and retreat explains a ∼0.15 m relative sea-level oscillation recorded within the peat layer subsequently submerged as a result of the AD 1964 earthquake. Before both this and the ∼850 cal yr BP earthquake, diatom assemblages suggest pre-seismic relative sea-level rise of ∼0.12±0.13 m, representing possible precursors to great earthquakes.     

Real-time application of an oil spill movement prediction system

This paper deals with the prediction, in real time, of the motion of experimental oil slicks. The experiments were conducted during September 1983 offshore near Halifax on the east coast of Canada. The objectives of the experiments were (i) to determine the suitability of oil spill dispersants as countermeasures and (ii) the testing and verification of oil spill trajectory models and systems.The Atmospheric Environment Service (AES) participated in the experiments to test the capability of its oil spill motion prediction system in providing real-time trajectory forecasts. The experiment consisted of three sets of spills. Each set had a control slick and a test slick. Sixteen barrels of crude oil were used in each spill. The test slicks were used to test the effectiveness of various dispersants, the control slicks were used to verify trajectory forecasts.The spill trajectories and oil weathering information obtained from the system during the experiments demonstrated the relative ease with which the system could handle the required input and provide timely forecasts. The accuracy of these forecast trajectories was confirmed by observations, and their utility was demonstrated by their application in the operational decision-making process.     

Use of Regional Geochemical Survey Data and exploratory statistics to estimate natural condition concentrations for trace metals in stream sediments: a case study for the Cook Inlet watershed,Alaska

The United States and other nations use the term natural conditions or reference conditions in legislation providing for the protection of aquatic ecosystems. Natural or reference conditions are generally used to describe environmental conditions in an aquatic resource before any human introduced pollution. The natural or reference conditions are used in establishing water quality criteria for protection of aquatic resources, helping classify aquatic resources within a regulatory category, and for assessing effectiveness of aquatic resource restoration actions. Regional scale geochemical mapping of stream sediments is available for many countries that when combined with exploratory data analysis and geospatial data can be used to establish screening level natural conditions for trace metals in stream sediments. This approach is applied to the Cook Inlet watershed in Alaska using the US Geological Survey National Geochemical Survey stream sediment trace metals data. Upper concentration limits are developed for As, Cr, Cu, Pb, Hg, Ni, and Zn in the Cook Inlet watershed to aid in screening sediments for potential anthropogenic contamination.     

A social assessment of the Hebei-Spirit oil spill

This paper examines the early social consequences of the largest oil spill in Korea from December 2007 up to May 2008. The focus is on the social impact of the oil spill and its social implications in three major areas of oil spill response: (1) clean-up operations, (2) compensation, and (3) ecological impact. The paper highlights both the positive and negative consequences of the spill and the significance of the early social assessment to understand subsequent responses and adaptation in the long run.     

Response of the phoxocephalid amphipod,Rhepoxynius abronius,to a small oil spill in Yaquina Bay,Oregon

A spill of approximately 284,000 liters of Bunker C and diesel fuel oils occurred at the entrance of Yaquina Bay, Oregon, following the wreck of the freighterBlue Magpie on 19 November 1983. A portion of this oil entered the lower estuary and was deposited on subtidal benthic habitats occupied by the phoxocephalid amphipodRhepoxynius abronius. This species is particularly sensitive to contaminants in sediment and its life history had previously been studied at the same sites affected by the spill. The oil was initially present as small, sand-coated globules at the study site, and persisted in association with detritus and sediment for months. Bioassays withRhepoxynius abronius showed that the oil globules were not acutely toxic unless mixed into the sediment at concentrations of 1.0 parts per thousand or greater. A series of 10-d bioassays before and after the spill showed that sediment collected from oiled subtidal sites did not become acutely toxic to this species. Although the density of theR. abronius population declined by 75% after the spill, similar declines of the same population were observed at this site in fall 1980. Oil-exposedR. abronius from Yaquina Bay were slightly more sensitive to cadmium in sediment than individuals from Whidbey Island, Puget Sound, Washington. Although mean fecundity was greater in 1984 than in 1981, recruitment following the spill was lower than in the 1980–1981 study. Thus, there is limited evidence for a small impact of the oil spill on this sensitive amphipod.     

Weathering of fuel oil spill on the east Mediterranean coast, Ashdod, Israel

Residual fuel oil spilled into the sea from the Eshkol power station on 8 February, 1998 contaminated about 9 km of the foreshore north of the Ashdod harbour. A study of the aliphatic, polycyclic alkane and polyaromatic hydrocarbon (PAH) composition of the spilled oil shows rapid weathering in the early stages followed by gradual slowdown after about three months. Weathering of isoprenoids and PAH compounds and variation in Pr/Ph ratio appear to occur almost contemporaneously with that of n-alkanes, at a relatively moderate level of degradation, when much of the >C₂₀ n-alkane envelope is still well preserved. Depletion of various compounds in accordance with molecular size rather than molecular structure appears to imply that physical weathering processes, i.e. evaporation and perhaps flushing due to wave energy, might have played an important role in the degradation of the spilled residual fuel oil in this study case.     

Hazard assessment of the Tidal Inlet landslide and potential subsequent tsunami, Glacier Bay National Park, Alaska

An unstable rock slump, estimated at 5 to 10 × 10⁶ m³, lies perched above the northern shore of Tidal Inlet in Glacier Bay National Park, Alaska. This landslide mass has the potential to rapidly move into Tidal Inlet and generate large, long-period-impulse tsunami waves. Field and photographic examination revealed that the landslide moved between 1892 and 1919 after the retreat of the Little Ice Age glaciers from Tidal Inlet in 1890. Global positioning system measurements over a 2-year period show that the perched mass is presently moving at 3–4 cm annually indicating the landslide remains unstable. Numerical simulations of landslide-generated waves suggest that in the western arm of Glacier Bay, wave amplitudes would be greatest near the mouth of Tidal Inlet and slightly decrease with water depth according to Green’s law. As a function of time, wave amplitude would be greatest within approximately 40 min of the landslide entering water, with significant wave activity continuing for potentially several hours.     

Measuring individual vulnerability to floods in the lower and middle Grijalva River Basin,Tabasco, Mexico

Natural Hazards - We built an easy-to-interpret individual vulnerability index to floods that is amenable for empirical testing and may be adapted to any perceived hazard or ecological setting. An...     

A procedure for mapping vulnerability of sea-coastal zones to oil

An algorithm for mapping the vulnerability of sea-coastal zones is described. Normalization of the distribution densities of the biotic groups to the annual average abundance for presenting these data in identical measurement units is offered. Sensitivity of biota to oil should be normalized to the maximum permissible concentrations for the species inhabiting the water column and to the maximum permissible thickness of the film that has contacted with the water surface. All parameters should be estimated by the metric scale. The proposed algorithm makes it possible to calculate the vulnerability of a sea-coastal zone to oil pollution caused by oil spills.     

PAH refractory index as a source discriminant of hydrocarbon input from crude oil and coal in Prince William Sound,Alaska

Geochemical correlation and differentiation of hydrocarbons from crude oils and coals is difficult. The complex mixture of the hydrocarbon constituents and the dynamic nature of these constituents in the environment as they weather contribute to this difficulty. A new parameter, the polycyclic aromatic hydrocarbon (PAH) refractory index, is defined here to help in this correlation. The PAH refractory index is a ratio of two of the most refractory constituents of most crude oils, namely triaromatic steranes and monomethylchrysenes. These are among the most persistent compounds in oil after deposition in the environment and thus retain reliably the signature of the original petroleum input. This index is utilized in Prince William Sound (PWS) to differentiate three different oils, as well as to provide evidence that coal, not oil, is the dominant source of the PAHs which are prominent constituents of marine sediments from PWS and the Gulf of Alaska.     

Particulate oil spill recovery. I,Oil sorption properties of plastic foams

Reusable, reticulated, polyurethane foams are broadcast at sea, absorb oil in the presence of water, are recovered, oil removed and foam particles rebroadcast. Combining dimensional and mathematical analysis with experimental data, a mathematical model of foam sorption efficacy and rate is developed showing the system to be practical. Oil viscosity, wave height, recovery ship speed, and system geometry influence foam selection.     

地下水易污性评价方法——DRASTIC指标体系

本文较详细地介绍了目前欧美国家在地下水易污性评价中所广泛采用的ＤＲＡＳＴＩＣ指标体系方法,对其中所含的地下水埋深,含水层的净补给,岩性,土壤类型,渗流区介质,水力传导系数７个参数的评分以及在评分过程中所应注意的问题进行了具体的阐述,最后简要介绍了ＤＲＡＳＴＩＣ易污性指标体系法在大连沿海地区地下水易污性评价中应用的情况,实际应用表明该方法可适用于我国广大地区的地下水易污性评价工作。     

Effects of rainfall,geomorphological and geometrical variables on vulnerability of the lower Mississippi River levee system to slump slides

This study investigated the importance of rainfall and various geomorphological and geometrical factors to the vulnerability of earthen levees to slump slides. The study was performed using a database including 34 slump slides that occurred in the lower Mississippi River levee system from 2008 to 2009. The impact of rainfall within the six months prior to slide occurrence was studied for 23 slides for which an accurate occurrence date was available. Several variables were used to develop a logistic regression model to predict the probability of slump slide occurrence. The proposed model was verified for both slide and non-slide cases. The regression analysis depicts the impact of channel width, river sinuosity index, riverbank erosion, channel shape condition and distance to river. Excluding the sinuosity index, the impact of the other independent variables examined was found to be significant. Occurrence of riverbank erosion around the slide locations was the most significant predictor factor. A channel width of less than 1000?m was ranked as the second most significant variable. The proposed model can aid in locating high-risk areas on levees in order to take prompt protective measures, increase monitoring efforts and enable early response under emergency conditions.     

Evaluation of groundwater vulnerability in the lower Varuna catchment area,Uttar Pradesh,India using AVI concept

Groundwater vulnerability assessments calculate the sensitivity of quality of groundwater to an imposed contaminant load which is essential element of the aquifer management plans. Seventy five groundwater samples have been analyzed for different chemical parameters to understand the groundwater quality of the lower Varuna river basin, Uttar Pradesh, India. The intrinsic groundwater vulnerability map of the lower Varuna catchment area in the north of the city of Varanasi (India) shows a high dependency on the depth to groundwater. The topmost layer of alluvial silty clay, protects the groundwater against contamination in this urban area, but the retention time in the unsaturated zone can be estimated to several months only. The input dataset is very sparse i.e. groundwater levels were measured twice (pre- and post-monsoon 2009) and the geological map shows only alluvium as the outcrop. Several boreholes in this area show, that the alluvium has a thickness of about 4 m and below that are fine grained sands. The surface information does not allow the development of a risk map since land use changes very fast and contamination areas can not be identified accurately. The vulnerability maps developed in this study have become important tools for environmental planning and predictive management of the groundwater resources in the fast urbanizing region in the Varanasi area.     

Scale implications and evolution of a social vulnerability index in Atlanta,Georgia, USA

Natural Hazards - The implications of hazards on populations are accentuated or alleviated by the nature of social systems, yet the multi-scalar variations of socioeconomic and demographic...     

Late Pleistocene and Holocene glaciation of the Fish Lake valley,northeastern Alaska Range,Alaska

We reconstructed a chronology of glaciation spanning from the Late Pleistocene through the late Holocene for Fish Lake valley in the north‐eastern Alaska Range using ¹⁰Be surface exposure dating and lichenometry. After it attained its maximum late Wisconsin extent, the Fish Lake valley glacier began to retreat ca. 16.5 ka, and then experienced a readvance or standstill at 11.6 ± 0.3 ka. Evidence of the earliest Holocene glacial activity in the valley is a moraine immediately in front of Little Ice Age (LIA) moraines and is dated to 3.3–3.0 ka. A subsequent advance culminated at ca. AD 610–900 and several LIA moraine crests date to AD 1290, 1640, 1860 and 1910. Our results indicate that ¹⁰Be dating from high‐elevation sites can be used to help constrain late Holocene glacial histories in Alaska, even when other dating techniques are unavailable. Close agreement between ¹⁰Be and lichenometric ages reveal that ¹⁰Be ages on late Holocene moraines may be as accurate as other dating methods. Copyright © 2009 John Wiley & Sons, Ltd.     

Magma storage prior to the 1912 eruption at Novarupta, Alaska

New analytical and experimental data constrain the storage and equilibration conditions of the magmas erupted in 1912 from Novarupta in the 20th century's largest volcanic event. Phase relations at H₂O+CO₂ fluid saturation were determined for an andesite (58.7 wt% SiO₂) and a dacite (67.7 wt%) from the compositional extremes of intermediate magmas erupted. The phase assemblages, matrix melt composition and modes of natural andesite were reproduced experimentally under H₂O-saturated conditions (i.e., P_H2O=P_TOT) in a negatively sloping region in T-P space from 930 °C/100 MPa to 960 °C/75 MPa with fO₂~NNO+1. The H₂O-saturated equilibration conditions of the dacite are constrained to a T-P region from 850 °C/50 MPa to 880 °C/25 MPa. If H₂O-saturated, these magmas equilibrated at (and above) the level where co-erupted rhyolite equilibrated (~100 MPa), suggesting that the andesite-dacite magma reservoir was displaced laterally rather than vertically from the rhyolite magma body. Natural mineral and melt compositions of intermediate magmas were also reproduced experimentally under saturation conditions with a mixed (H₂O + CO₂) fluid for the same range in P_H2O. Thus, a storage model in which vertically stratified mafic to silicic intermediate magmas underlay H₂O-saturated rhyolite is consistent with experimental findings only if the intermediates have X_H2O^fl=0.7 and 0.9 for the extreme compositions, respectively. Disequilibrium features in natural pumice and scoria include pristine minerals existing outside their stability fields, and compositional zoning of titanomagnetite in contact with ilmenite. Variable rates of chemical equilibration which would eliminate these features constrain the apparent thermal excursion and re-distribution of minerals to the time scale of days.     

Developmental geology of coalbed methane from shallow to deep in Rocky Mountain basins and in Cook Inlet–Matanuska basin, Alaska, U.S.A. and Canada

The Rocky Mountain basins of western North America contain vast deposits of coal of Cretaceous through early Tertiary age. Coalbed methane is produced in Rocky Mountain basins at depths ranging from 45 m (150 ft) to 1,981 m (6,500 ft) from coal of lignite to low-volatile bituminous rank. Although some production has been established in almost all Rocky Mountain basins, commercial production occurs in only a few. Despite more than two decades of exploration for coalbed methane in the Rocky Mountain region, it is still difficult to predict production characteristics of coalbed methane wells prior to drilling. Commonly cited problems include low permeabilities, high water production, and coals that are significantly undersaturated with respect to methane. Sources of coalbed gases can be early biogenic, formed during the early stages of coalification, thermogenic, formed during the main stages of coalification, or late stage biogenic, formed as a result of the reintroduction of methane-generating bacteria by groundwater after uplift and erosion. Examples of all three types of coalbed gases, and combinations of more than one type, can be found in the Rocky Mountain region. Coals in the Rocky Mountain region achieved their present ranks largely as a result of burial beneath sediments that accumulated during the Laramide orogeny (Late Cretaceous through the end of the Eocene) or shortly after. Thermal events since the end of the orogeny have also locally elevated coal ranks. Coal beds in the upper part of high-volatile A bituminous rank or greater commonly occur within much more extensive basin-centered gas deposits which cover large areas of the deeper parts of most Rocky Mountain basins. Within these basin-centered deposits all lithologies, including coals, sandstones, and shales, are gas saturated, and very little water is produced. The interbedded coals and carbonaceous shales are probably the source of much of this gas. Basin-centered gas deposits become overpressured from hydrocarbon generation as they form, and this overpressuring is probably responsible for driving out most of the water. Sandstone permeabilities are low, in part because of diagenesis caused by highly reactive water given off during the early stages of coalification. Coals within these basin-centered deposits commonly have high gas contents and produce little water, but they generally occur at depths greater than 5,000 ft and have low permeabilities. Significant uplift and removal of overburden has occurred throughout the Rocky Mountain region since the end of the Eocene, and much of this erosion occurred after regional uplift began about 10 Ma. The removal of overburden generally causes methane saturation levels in coals to decrease, and thus a significant drop in pressure is required to initiate methane production. The most successful coalbed methane production in the Rocky Mountain region occurs in areas where gas contents were increased by post-Eocene thermal events and/or the generation of late-stage biogenic gas. Methane-generating bacteria were apparently reintroduced into the coals in some areas after uplift and erosion, and subsequent changes in pressure and temperature, allowed surface waters to rewater the coals. Groundwater may also help open up cleat systems making coals more permeable to methane. If water production is excessive, however, the economics of producing methane are impacted by the cost of water disposal.     

Measuring the vulnerability of populations susceptible to lead contamination in the Dominican Republic: evaluating composite index construction methods

There are several suspected sources of lead contamination in the Dominican Republic (DR) to which populations, to a greater or lesser extent, may be exposed. These sources include: a lead battery recycling plant, a gold mine and vehicles using leaded gasoline. In this paper we create and compare indices of spatial vulnerability using different index construction methods including: the weighted average, ordered weighted average, and Data Envelopment Analysis. The vulnerability attributes used to create these indices include: exposure to lead effluents in water from the gold mine as measured by distance from potentially contaminated water, point source lead air emissions from the battery recycling plant estimated by air plume analysis; and mobile source exposure to lead emissions from road transportation measured by potential traffic impacts. The intensities of vulnerability to lead of the towns and cities in the DR, produced by each of the different index construction methods, are compared and evaluated.     

基于脆弱指数法的曹妃甸海岸带脆弱性评价

了解海岸带脆弱程度对于海岸带可持续开发和防灾避灾是至关重要的.基于脆弱指数法选取风暴潮灾害风险等6项因子构建指标体系对曹妃甸地区海岸带脆弱程度进行评价,采用2种赋权重方法对比讨论结果的合理性.结果表明:海岸带脆弱程度由近岸至内陆呈逐渐降低趋势,高脆弱和较高脆弱区主要分布在涧河至滦南第三盐场近岸、高尚堡盐场至大清河盐场近岸;风暴潮灾害风险和地面沉降速率是影响曹妃甸海岸带脆弱性高低的2个主要指标.