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At least 649 records · Page 36Linked to original sources

A digital elevation model for simulating the 1945 Makran tsunami in Karachi Harbour

The digital elevation model documented here provides a tool for calibrating tsunami models to effects of the 1945 Makran tsunami that were observed in Karachi Harbour. The DEM bathymetry is derived from soundings made mainly during the first 8 years post-tsunami. While deficient in its portrayal of interior tidelands and upland topography, the DEM accurately represents the setting of a tide gauge that recorded the 1945 tsunami.

Karachi Harbour↗

Karachi tides during the 1945 Makran tsunami

This paper extends and detides a Karachi tide-gauge record as an observational basis for assessing Indian Ocean tsunami risk. The extended marigram encompasses the time of the great 1945 Makran earthquake of early November 28, local time, and of the ensuing tsunami, which continued into November 29. The marigram was published previously as a 9-h excerpt that begins 1 h after the earthquake. The full marigram presented here covers most of 17 days from November 15 to December 1. Gaps include a tsunami-induced outage that may help explain why the highest water level gauged is 1 m below the maximum water level reported nearby. The detiding method computes a reference tidal curve that disregards all observations from November 28 and 29. For those 2 days, the reference tide is guided by Admiralty tide tables and, secondarily, by high waters and low waters gauged before and after. As in previous estimates, the detided tsunami crests about 0.5 m above ambient tide, but now with the possibility that the gauge failed to record a higher wave. Anomalies described for the first time include an early one that likely resulted from a recognized problem with the Karachi tide station, but which might instead represent an earthquake precursor.

Karachi↗

Groundwater salinity and the effects of produced water disposal in the Lost Hills-Belridge oilfields, Kern County, California

Increased oil and gas production in many areas has led to concerns over the effects these activities may be having on nearby groundwater quality. In this study we determine the lateral and vertical extent of groundwater with less than 10,000 milligrams per liter (mg/l) total dissolved solids (TDS) near the Lost Hills-Belridge oilfields in northwestern Kern County, California and document evidence of impacts by produced water disposal within the Tulare aquifer and overlying alluvium—the primary protected aquifers in the area. The depth at which groundwater salinity surpasses 10,000 mg/l ranges from 150 m (500 ft [ft]) in the northwestern part of the study area to 490 to 550 m (1,600-1,800 ft) in the south and east respectively as determined by geophysical log analysis and lab analysis of produced water samples. Comparison of logs from replacement wells with logs from their older counterparts shows relatively higher resistivity intervals representing the vadose zone or fresher groundwater being replaced by intervals with much lower resistivity due to infiltration of brines from surface disposal ponds and injection of brines into disposal wells. The effect of the surface ponds is confined to the alluvial aquifer—the underlying Tulare aquifer is largely protected by a regional clay layer at the base of the alluvium. Sand layers affected by injection of produced waters in nearby disposal wells often exhibit log resistivity profiles that change from high resistivity in their upper parts to low resistivity near the base due to stratification by gravity segregation of the denser brines within each affected sand. The effects of produced water injection are mainly evident within the Tulare Formation and can be noted as far as 550 m (1,800 ft) from the main group of disposal wells located along the east flank of South Belridge.

California↗

Tracking solutes and water from subsurface drip irrigation application of coalbed methane-produced waters, Powder River Basin, Wyoming

One method to beneficially use water produced from coalbed methane (CBM) extraction is subsurface drip irrigation (SDI) of croplands. In SDI systems, treated CBM water (injectate) is supplied to the soil at depth, with the purpose of preventing the buildup of detrimental salts near the surface. The technology is expanding within the Powder River Basin, but little research has been published on its environmental impacts. This article reports on initial results from tracking water and solutes from the injected CBM-produced waters at an SDI system in Johnson County, Wyoming. In the first year of SDI operation, soil moisture significantly increased in the SDI areas, but well water levels increased only modestly, suggesting that most of the water added was stored in the vadose zone or lost to evapotranspiration. The injectate has lower concentrations of most inorganic constituents relative to ambient groundwater at the site but exhibits a high sodium adsorption ratio. Changes in groundwater chemistry during the same period of SDI operation were small; the increase in groundwater-specific conductance relative to pre-SDI conditions was observed in a single well. Conversely, groundwater samples collected beneath another SDI field showed decreased concentrations of several constituents since the SDI operation. Groundwater-specific conductance at the 12 other wells showed no significant changes. Major controls on and compositional variability of groundwater, surface water, and soil water chemistry are discussed in detail. Findings from this research provide an understanding of water and salt dynamics associated with SDI systems using CBM-produced water.

Wyoming↗

Unraveling the stratigraphy of the Oriskany Sandstone: A necessity in assessing its site-specific carbon sequestration potential

The widespread distribution, favorable reservoir characteristics, and depth make the Lower Devonian Oriskany Sandstone a viable sequestration target in the Appalachian Basin. The Oriskany Sandstone is thickest in the structurally complex Ridge and Valley Province, thins toward the northern and western basin margins, and is even absent in other parts of the basin (i.e., the no-sand area of northwestern Pennsylvania). We evaluated four regions using petrographic data, core analyses, and geophysical log analyses. Throughout the entire study area, average porosities range from 1.35 to 14%. The most notable porosity types are primary intergranular, secondary dissolution, and fracture porosity. Intergranular primary porosity dominates at stratigraphic pinch-out zones near the Oriskany no-sand area and at the western limit of the Oriskany Sandstone. Secondary porosity occurs from dissolution of carbonate constituents primarily in the combination-traps natural gas play extending through western Pennsylvania, western West Virginia, and eastern Ohio. Fracture porosity dominates in the central Appalachian Plateau Province and Valley and Ridge Province. Based on average porosity, the most likely regions for successful sequestration in the Oriskany interval are (1) updip from Oriskany Sandstone pinch-outs in eastern Ohio, and (2) western Pennsylvania, western West Virginia, and eastern Ohio where production occurs from a combination of stratigraphic and structural traps. Permeability data, where available, were used to further evaluate the potential of these regions. Permeability ranges from 0.2 to 42.7 md. Stratigraphic pinch-outs at the northern and western limits of the basin have the highest permeabilities. We recommend detailed site assessments when evaluating the sequestration potential of a given injection site based on the variability observed in the Oriskany structure, lithology, and reservoir characteristics. ?? 2009. The American Association of Petroleum Geologists/Division of Environmental Ceosciences. All rights reserved.

Environmental Geosciences↗

Depositional and diagenetic variability within the Cambrian Mount Simon Sandstone: Implications for carbon dioxide sequestration

The Cambrian Mount Simon Sandstone is the major target reservoir for ongoing geologic carbon dioxide (CO 2 ) sequestration demonstrations throughout the midwest United States. The potential CO 2 reservoir capacity, reactivity, and ultimate fate of injected CO 2 depend on textural and compositional properties determined by depositional and diagenetic histories that vary vertically and laterally across the formation. Effective and efficient prediction and use of the available pore space requires detailed knowledge of the depositional and diagenetic textures and mineralogy, how these variables control the petrophysical character of the reservoir, and how they vary spatially. Here, we summarize the reservoir characteristics of the Mount Simon Sandstone based on examination of geophysical logs, cores, cuttings, and analysis of more than 150 thin sections. These samples represent different parts of the formation and depth ranges of more than 9000 ft ( 2743 m) across the Illinois Basin and surrounding areas. This work demonstrates that overall reservoir quality and, specifically, porosity do not exhibit a simple relationship with depth, but vary both laterally and with depth because of changes in the primary depositional facies, framework composition (i.e., feldspar concentration), and diverse diagenetic modifications. Diagenetic processes that have been significant in modifying the reservoir include formation of iron oxide grain coatings, chemical compaction, feldspar precipitation and dissolution, multiple generations of quartz overgrowth cementation, clay mineral precipitation, and iron oxide cementation. These variables provide important inputs for calculating CO 2 capacity potential, modeling reactivity, and are also an important baseline for comparisons after CO 2 injection.

Indiana↗

Modeling geologic sequestration of carbon dioxide in a deep saline carbonate reservoir with TOUGH2–ChemPlugin, a new tool for reactive transport modeling

This paper outlines the development and demonstration of a new tool, TOUGH2–ChemPlugin (T2CPI) for predicting rock–water–CO 2 interaction following injection of supercritical CO 2 into a heterogeneous carbonate system. Specifically, modeling capabilities of TOUGH2, which examines multiphase flow and supercritical CO 2 behavior, were combined with the geochemical modeling capabilities of The Geochemist’s Workbench ® (GWB), using ChemPlugin TM . ChemPlugin is a self-linking re-entrant software object that, when coupled to a transport simulator, retains the flow and transport capabilities of the simulator but enables incorporation of reactive chemistry via GWB. To test and assess the capabilities of T2CPI, results from T2CPI simulations were compared to those of TOUGHREACT, using the same carbonate reservoir parameters (based on the Dollar Bay Formation of the South Florida Basin). Overall, results of simulations from TOUGHREACT and T2CPI were very similar for nearly all evaluated parameters. Dissimilarities between the two programs included qualitative differences in how TOUGHREACT and T2CPI predicted calcite dissolution and the subsequent spatial pattern of the porosity gain caused by how each handles evaporation of water near the injection point. The TOUGHREACT program is a proven, widely used tool for evaluating CO 2 –brine–rock interaction following supercritical CO 2 injection. The T2CPI tool offers similar capabilities and strengths of TOUGHREACT, with the ability to read in and use databases for a wide range of activity coefficient types. This program also has abilities to use a wide range of kinetic constraints, define those kinetic constraints with scripts or compiled libraries, account for colloidal transport, and/or account for a wide range of surface sorption models.

Florida↗

Reconstructing suspended sediment mercury contamination of a steep, gravel-bed river using reservoir theory

We use sediment ages and mercury (Hg) concentrations to estimate past and future concentrations in the South River, Virginia, where Hg was released between 1930 and 1950 from a manufacturing process related to nylon production. In a previous study, along a 40 km (25 mi) reach, samples were collected from 26 of 54 fine-grained deposits that formed in the lee of large wood obstructions in the channel and analyzed for grain size, Hg concentration, and organic content. We also obtained radiometric dates from six deposits. To create a history that reflects the full concentration distribution (which contains concentrations as high as 900 mg/kg [900 ppm]), here, we treat the deposits as a single reservoir exchanging contaminated sediments with the overlying water column, and assume that the total sediment mass in storage and the distribution of sediment ages are time invariant. We use reservoir theory to reconstruct the annual history of Hg concentration on suspended sediment using data from our previous study and new results presented here. Many different reconstructed histories fit our data. To constrain results, we use information from a well-preserved core (and our estimate of the total mass of Hg stored in 2007) to specify the years associated with the peak concentration of 900 mg/kg. Our results indicate that around 850 kg (1874 lb) of Hg was stored in the deposits between 1955 and 1961, compared to only 80 kg (176 lb) today. Simulations of future Hg remediation suggest that 100-yr timescales will be needed for the South River to remove Hg-contaminated sediments from the channel perimeter through natural processes.

Environmental Geosciences↗

Environmental impacts of oil production on soil, bedrock, and vegetation at the U.S. Geological Survey Osage-Skiatook Petroleum Environmental Research site A, Osage County, Oklahoma

The U.S. Geological Survey is investigating the impacts of oil and gas production on soils, groundwater, surface water, and ecosystems in the United States. Two sites in northeastern Oklahoma (sites A and B) are presently being investigated under the Osage–Skiatook Petroleum Environmental Research project. Oil wells on the lease surrounding site A in Osage County, Oklahoma, produced about 100,000 bbl of oil between 1913 and 1981. Prominent production features on the 1.5-ha (3.7-ac) site A include a tank battery, an oil-filled trench, pipelines, storage pits for both produced water and oil, and an old power unit. Site activities and historic releases have left open areas in the local oak forest adjacent to these features and a deeply eroded salt scar downslope from the pits that extends to nearby Skiatook Lake. The site is underlain by surficial sediments comprised of very fine-grained eolian sand and colluvium as much as 1.4 m (4.6 ft) thick, which, in turn, overlie flat-lying, fractured bedrock comprised of sandstone, clayey sandstone, mudstone, and shale. A geophysical survey of ground conductance and concentration measurements of aqueous extracts (1:1 by weight) of core samples taken in the salt scar and adjacent areas indicate that unusual concentrations of NaCl-rich salt are present at depths to at least 8 m (26 ft) in the bedrock; however, little salt occurs in the eolian sand. Historic aerial photographs, anecdotal reports from oil-lease operators, and tree-ring records indicate that the surrounding oak forest was largely established after 1935 and thus postdates the majority of surface damage at the site. Blackjack oaks adjacent to the salt scar have anomalously elevated chloride ( 400 ppm) in their leaves and record the presence of NaCl-rich salt or salty water in the shallow subsurface. The geophysical measurements also indicate moderately elevated conductance beneath the oak forest adjoining the salt scar.

Oklahoma↗

Progression of methanogenic degradation of crude oil in the subsurface

Our results show that subsurface crude-oil degradation rates at a long-term research site were strongly influenced by small-scale variations in hydrologic conditions. The site is a shallow glacial outwash aquifer located near Bemidji in northern Minnesota that became contaminated when oil spilled from a broken pipeline in August 1979. In the study area, separate-phase oil forms a subsurface oil body extending from land surface to about 1 m (3.3 ft) below the 6–8-m (20–26 ft)-deep water table. Oil saturation in the sediments ranges from 10–20% in the vadose zone to 30–70% near the water table. At depths below 2 m (6.6 ft), degradation of the separate-phase crude oil occurs under methanogenic conditions. The sequence of methanogenic alkane degradation depletes the longer chain n-alkanes before the shorter chain n-alkanes, which is opposite to the better known aerobic sequence. The rates of degradation vary significantly with location in the subsurface. Oil-coated soils within 1.5 m (5 ft) of land surface have experienced little degradation where soil water saturation is less than 20%. Oil located 2–8 m (6.6–26 ft) below land surface in areas of higher recharge has been substantially degraded. The best explanation for the association between recharge and enhanced degradation seems to be increased downward transport of microbial growth nutrients to the oil body. This is supported by observations of greater microbial numbers at higher elevations in the oil body and significant decreases with depth in nutrient concentrations, especially phosphorus. Our results suggest that environmental effects may cause widely diverging degradation rates in the same spill, calling into question dating methods based on degradation state.

Environmental Geosciences↗

Impacts of petroleum production on ground and surface waters: Results from the Osage-Skiatook Petroleum Environmental Research A site, Osage County Oklahoma

Kharaka has been a research hydrogeochemist with the U.S. Geological Survey since1975. His current research covers the fields of water-rock-gas interactions, CO 2 sequestration, contamination from agricultural drainage and petroleum produced water, and fluid-fault interactions. Kharaka has authored more than 100 scientific papers and book chapters and has delivered about 200 presentations. He received his Ph.D. from the University of California, Berkeley, in 1971. Thordsen is a geologist, employed with the U.S. Geological Survey since 1981 and presently working in the project team Hydrogeochemistry of Fine Grained Sediments, in the Water Resources Division, National Research Program. His recent research covers water-rock interactions and geochemical modeling in geothermal systems, fault-fluid systems, and petroleum produced water brine impacts. He received his M.S. in geology from the Ohio State University in 1988. Kakouros has been a hydrogeologist in the U.S. Geological Survey Water Resources Division in Menlo Park, California, since 1999. His current research covers the fields of Se contamination from agricultural drainage, CO 2 sequestration, and contamination from petroleum and petroleum-produced water. Kakouros received his M.Sc. from the San Jose State University in 2001. Herkelrath is a physicist in the U.S. Geological Survey's Water Resources Division National Research Program in Menlo Park, California. Herkelrath received his Ph.D. in physics from the University of Wisconsin at Madison. His recent research interests include multiphase flow and solute transport modeling in shallow ground-water systems where oil or brine is present.

Oklahoma↗

Measuring permanence of CO 2 storage in saline formations: The Frio experiment

If CO 2 released from fossil fuel during energy production is returned to the subsurface, will it be retained for periods of time significant enough to benefit the atmosphere? Can trapping be assured in saline formations where there is no history of hydrocarbon accumulation? The Frio experiment in Texas was undertaken to provide answers to these questions. One thousand six hundred metric tons of CO 2 were injected into the Frio Formation, which underlies large areas of the United States Gulf Coast. Reservoir characterization and numerical modeling were used to design the experiment, as well as to interpret the results through history matching. Closely spaced measurements in space and time were collected to observe the evolution of immiscible and dissolved CO 2 during and after injection. The high-permeability, steeply dipping sandstone allowed updip flow of supercritical CO 2 as a result of the density contrast with formation brine and absence of a local structural trap. The front of the CO 2 plume moved more quickly than had been modeled. By the end of the 10-day injection, however, the plume geometry in the plane of the observation and injection wells had thickened to a distribution similar to the modeled distribution. As expected, CO 2 dissolved rapidly into brine, causing pH to fall and calcite and metals to be dissolved. Postinjection measurements, including time-lapse vertical seismic profiling transects along selected azimuths, cross-well seismic topography, and saturation logs, show that CO 2 migration under gravity slowed greatly 2 months after injection, matching model predictions that significant CO 2 is trapped as relative permeability decreases.

Environmental Geosciences↗

Causes of hot-spot wetland loss in the Mississippi delta plain

Field surveys and sediment cores were used to estimate marsh erosion and land subsidence at Madison Bay, a well-known wetland loss hot spot in coastal Louisiana. Former marshes of Madison Bay are under about 1 m of water. Nearly two-thirds of the permanent flooding was caused by rapid subsidence in the late 1960s, whereas the other third was caused by subsequent erosion. Subsidence rates near Madison Bay since the 1960s ( 20 mm/yr) are an order of magnitude greater than deltaic subsidence rates averaged for the past 400 4000 yr ( 2 mm/yr). The rapid acceleration and unexpected decline in wetland losses in the Mississippi delta plain are difficult to explain on the basis of most physical and biogeochemical processes. There are, however, close temporal and spatial correlations among regional wetland loss, high subsidence rates, and large-volume fluid production from nearby hydrocarbon fields. The decreased rates of wetland loss since the 1970s may be related to decreased rates of subsidence caused by significantly decreased rates of subsurface fluid withdrawal. Annual fluid production from the Lapeyrouse, Lirette, and Bay Baptiste fields that encompass Madison Bay accelerated in the 1960s, peaked about 1970, and then declined abruptly. Large decreases in pore pressure in the Lapeyrouse field have likely altered subsurface stresses and reactivated a major fault that coincides with the wetland loss hot spot. Therefore, wetland losses at Madison Bay can be closely linked to rapid subsidence and possible fault reactivation induced by long-term, large-volume hydrocarbon production.

Environmental Geosciences↗

Forecasting eruptions in the Circum-Pacific

Many important advances have been made in the last few years in the techniques and approaches to forecasting volcanic eruptions. Yet some of the most dangerous volcanoes are in countries unable to provide either the equipment or the skills to monitor them and to warn endangered residents. This review of the many scientific, technical, social and even political factory involved in volcano forecasting will be of value to other scientists concerned with monitoring and coping with natural hazards and disasters.

Episodes, Journal of International Geoscience↗

Ground ruptures attributed to groundwater overexploitation damaging Jocotepec city in Jalisco, Mexico: 2016 field excursion of IGCP-641

IGCP Project 641 (Mechanisms, Monitoring and Modeling Earth Fissure generation and Fault activation due to subsurface Fluid exploitation – M3EF3) held its second international workshop from November 2 to 6, 2016, in Puerto Vallarta and included a two-day field trip to Guadalajara and Jocotepec in the Mexican state of Jalisco (Fig. 1a). M3EF3 is aimed at i) understanding the mechanisms that cause the formation of “ground ruptures”, as a response to changes in the stress state in the subsoil, ii) monitoring their occurrence, and iii) developing appropriate approaches to model their formation and growth. Notice that many times it is difficult to discern whether a particular instance of a “ruptured” land surface is due to an earth fissure with a surface manifestation or a surface failure associated with the activation of a pre-existing fault, especially where a fault has not been mapped and where there is no obvious scarp. Therefore, in M3EF3 we preferred to use the term “ground rupture”, to refer to both such occurrences.

Jalisco↗

Probabilistic assessment of precipitation-triggered landslides using historical records of landslide occurrence, Seattle, Washington

Ninety years of historical landslide records were used as input to the Poisson and binomial probability models. Results from these models show that, for precipitation-triggered landslides, approximately 9 percent of the area of Seattle has annual exceedance probabilities of 1 percent or greater. Application of the Poisson model for estimating the future occurrence of individual landslides results in a worst-case scenario map, with a maximum annual exceedance probability of 25 percent on a hillslope near Duwamish Head in West Seattle. Application of the binomial model for estimating the future occurrence of a year with one or more landslides results in a map with a maximum annual exceedance probability of 17 percent (also near Duwamish Head). Slope and geology both play a role in localizing the occurrence of landslides in Seattle. A positive correlation exists between slope and mean exceedance probability, with probability tending to increase as slope increases. Sixty-four percent of all historical landslide locations are within 150 m (500 ft, horizontal distance) of the Esperance Sand/Lawton Clay contact, but within this zone, no positive or negative correlation exists between exceedance probability and distance to the contact.

Washington↗

Usoi Landslide Dam and Lake Sarez, Pamir Mountains, Tajikistan

In 1911, a 2-km 3 (0.5-mi 3 ) earthquake-triggered rock slide blocked the Murgab River, southeastern Tajikistan, forming a still-existing, 600-m-high (1,970-ft-high) natural dam—the highest dam, natural or man-made, in the world. Lake Sarez, impounded by this blockage, is 60 km (37 mi) long, with a maximum depth of 550 m (1,800 ft) and a volume of approximately 17 km 3 (∼4 mi 3 ). This lake, which has never overtopped the dam, exits the downstream face as a series of large springs that regroup as the Murgab River. Freeboard between lake surface and the lowest point on the dam crest currently is approximately 50 m (∼165 ft), and the lake is rising at an average rate of 18.5 cm/yr (7.3 in./yr). If the blockage were to fail, a worst-case scenario could endanger tens or possibly hundreds of thousands of people in the Murgab, Bartang, Panj, and Amu Darya valleys downstream. Dam failure potentially could result from: 1) seismic shaking, 2) catastrophic overtopping caused by a landslide entering the lake from the valley wall at high velocity, 3) surface erosion caused by natural overtopping by the rising lake, 4) internal erosion (piping), 5) instability caused by lake pressure against the dam, or 6) slope instability of the dam faces. Occurrence of an overtopping wave resulting from a potential landslide high on the right bank of Lake Sarez seems to be the most realistic of these slight possibilities for failure. Because of the high cost of installing physical remediation to the dam in this rugged mountain area (no roads lead to the site), the main protective measures now being undertaken are hydrological monitoring at the dam and installation of a flood early warning system downstream.

Lake Sarez↗

Transient hazard model using radar data for predicting debris flows in Madison County, Virginia

During the rainstorm of June 27, 1995, roughly 330-750 mm of rain fell within a 16-hour period, initiating floods and over 600 debris flows in a small area (130 km2) of Madison County, VA. We developed a distributed version of Iverson's transient response model for regional slope stability analysis for the Madison County debris flows. This version of the model evaluates pore-pressure head response and factor of safety on a regional scale in areas prone to rainfall-induced shallow (<2-3 m) landslides. These calculations used soil properties of shear strength and hydraulic conductivity from laboratory measurements of soil samples collected from field sites where debris flows initiated. Rainfall data collected by radar every 6 minutes provided a basis for calculating the temporal variation of slope stability during the storm. The results demonstrate that the spatial and temporal variation of the factor of safety correlates with the movement of the storm cell. When the rainstorm was treated as two separate rainfall events and a larger hydraulic conductivity and friction angle than the laboratory values were used, the timing and location of landslides predicted by the model were in closer agreement with eyewitness observations of debris flows. Application of spatially variable initial pre-storm water table depth and soil properties may improve both the spatial and temporal prediction of instability.

Environmental & Engineering Geoscience↗