Deriving effects of pressure depletion on elastic framework moduli from sonic logs     

Anne-Kari Furre  Mona Andersen  Anita Smalø Moen  Randi Kristin Tønnessen 《Geophysical Prospecting》2009,57(3):427-437

We have developed a method to determine the effect of pore pressure depletion on elastic framework moduli, by utilizing sonic logs from wells drilled at different locations through a reservoir at varying depletion stages. This is done by first inverting the sonic logs for elastic framework bulk and shear moduli, thus carefully removing pressure dependent fluid effects. By crossplotting these elastic framework moduli against an increase in net stress (which is directly related to depletion), we derive the stress sensitivity of the elastic framework moduli. We found that the observed stress sensitivity was consistent with time-lapse seismic results and that the sensitivity derived from the sonic logs was much smaller than predicted by hydrostatic measurements on core samples. This method is applicable to depletion scenarios in mature fields and can be used both for modelling and inverting time-lapse seismic data for effects of pore pressure depletion on seismic data.  相似文献   

Organophosphates and Synthetic Musk Fragrances in Freshwater Streams in Hessen/Germany     

Kristin Quednow  Wilhelm Püttmann 《洁净——土壤、空气、水》2008,36(1):70-77

Four small freshwater river systems in Hessen, Germany, have been investigated with respect to seasonal and spatial concentration variations and transported load of the organophosphates tri‐n‐butyl phosphate (TBP), tris(2‐butoxyethyl)phosphate (TBEP), tris(2‐chloroethyl)phosphate (TCEP), tris(1‐chloro‐2‐propyl)phosphate (TCPP), and tris(1,3‐dichloro‐2‐propyl)phosphate (TDCPP) and the synthetic musk fragrances 1,3,4,6,7,8‐hexahydro‐4,6,6,7,8,8‐hexa‐methylcyclopenta‐[γ]‐2‐benzopyran (HHCB) and 7‐acetyl‐1,1,3,4,4,6‐hexamethyl‐1,2,3,4‐tetrahydronaphthalene (AHTN). Data originate from water samples collected in the time span from September 2003 to April 2005 at 25 sampling locations. The detection frequency for all compounds was about 90%. Mean concentration levels of organophosphates were 502 ng/L (TCPP), 276 ng/L (TBP), 183 ng/L (TBEP), 118 ng/L (TCEP), and 117 ng/L (TDCPP). The synthetic musk fragrances HHCB and ATHN were detected with mean concentrations of 141 and 46 ng/L, respectively. The variability of the concentration of all compounds was high with respect to space and time. The highest concentrations were observed in the Schwarzbach system characterized by the highest proportion of wastewater compared to the other river systems. Concentration levels of synthetic musk fragrances were significantly lower in summer times compared to winter times.  相似文献   

An Atlas of ShakeMaps and population exposure catalog for earthquake loss modeling     

Trevor I. Allen  David J. Wald  Paul S. Earle  Kristin D. Marano  Alicia J. Hotovec  Kuowan Lin  Michael G. Hearne 《Bulletin of Earthquake Engineering》2009,7(3):701-718

We present an Atlas of ShakeMaps and a catalog of human population exposures to moderate-to-strong ground shaking (EXPO-CAT) for recent historical earthquakes (1973–2007). The common purpose of the Atlas and exposure catalog is to calibrate earthquake loss models to be used in the US Geological Survey’s Prompt Assessment of Global Earthquakes for Response (PAGER). The full ShakeMap Atlas currently comprises over 5,600 earthquakes from January 1973 through December 2007, with almost 500 of these maps constrained—to varying degrees—by instrumental ground motions, macroseismic intensity data, community internet intensity observations, and published earthquake rupture models. The catalog of human exposures is derived using current PAGER methodologies. Exposure to discrete levels of shaking intensity is obtained by correlating Atlas ShakeMaps with a global population database. Combining this population exposure dataset with historical earthquake loss data, such as PAGER-CAT, provides a useful resource for calibrating loss methodologies against a systematically-derived set of ShakeMap hazard outputs. We illustrate two example uses for EXPO-CAT; (1) simple objective ranking of country vulnerability to earthquakes, and; (2) the influence of time-of-day on earthquake mortality. In general, we observe that countries in similar geographic regions with similar construction practices tend to cluster spatially in terms of relative vulnerability. We also find little quantitative evidence to suggest that time-of-day is a significant factor in earthquake mortality. Moreover, earthquake mortality appears to be more systematically linked to the population exposed to severe ground shaking (Modified Mercalli Intensity VIII+). Finally, equipped with the full Atlas of ShakeMaps, we merge each of these maps and find the maximum estimated peak ground acceleration at any grid point in the world for the past 35 years. We subsequently compare this “composite ShakeMap” with existing global hazard models, calculating the spatial area of the existing hazard maps exceeded by the combined ShakeMap ground motions. In general, these analyses suggest that existing global, and regional, hazard maps tend to overestimate hazard. Both the Atlas of ShakeMaps and EXPO-CAT have many potential uses for examining earthquake risk and epidemiology. All of the datasets discussed herein are available for download on the PAGER Web page (). T. I. Allen and M. G. Hearne—contracted through Synergetics Incorporated.  相似文献   

Enacting things through numbers: Taking nature into account/ing     

Kristin Asdal 《Geoforum》2008,39(1):123-132

In this article I make use of a combination of actor-network-theory, governmentality studies and feminist studies of science to show how nature is done or enacted within politics and administration. In particular I show how it relates to the theories and practices of economics and accounting. I explore the process by which the ‘critical limits’ of nature under the impact of acidification was created as a part of the politics and negotiations about acid rain. I demonstrate that even though the outcome was not ‘Nature’ as such, understood as a form of moral high-ground, the effect of this process was to produce ‘a nature as a whole’, in a process of unification. This I argue can only be understood relationally: ‘Nature’ is taken into account by way of accounting. In doing this I engage with Latour’s work on the politics of Nature and argue that nature is not necessarily such a deadly tool to politics as is sometimes taken for granted. Before we throw Nature out with our empirical studies of sciences, natures and politics, in the plural, we need to look first at how Nature-wholes emerge, are enacted, and take part in politics.  相似文献   

Towards a multi-scale approach for an Earth observation-based assessment of natural resource exploitation in conflict regions     

Elisabeth Schoepfer  Kristin Spröhnle  Olaf Kranz  Xavier Blaes  Jan Kolomaznik  Filip Hilgert 《国际地球制图》2017,32(10):1139-1158

The exploitation of resources, if not properly managed, can lead to spoiling natural habitats as well as to threatening people’s health, livelihoods and security. The paper discusses a multi-scale Earth observation-based approach to provide independent information related to exploitation activities of natural resources for countries which are experiencing armed conflict. The analyses are based on medium to very high spatial resolution optical satellite data. Object-based image analysis is used for information extraction at these different scales. On a subnational level, conflict-related land cover changes as an indication of potential hot spots for exploitation activities are classified. The regional assessment provides information about potential activity areas of resource exploitation, whereas on a local scale, a site-specific assessment of exploitation areas is performed. The study demonstrates the potential of remote sensing for supporting the monitoring and documentation of natural resource exploitation in conflict regions.  相似文献   

Effects of suspended sediment characteristics and bed sediment transport on streambed clogging     

Kristin J. Rehg  Aaron I. Packman  Jianhong Ren 《水文研究》2005,19(2):413-427

Fine sediment deposition in streambeds can reduce pore water fluxes and the overall rate of hyporheic exchange, producing deleterious effects on benthic and hyporheic ecological communities. To increase understanding of the factors that control the reduction of hyporheic exchange by fine sediment deposition, we conducted experiments in a laboratory flume to observe changes in the rates of solute exchange and kaolinite clay deposition as substantial amounts of kaolinite accumulated in the streambed. Two long‐term experiments were conducted, with durations of 14 days and 29 days. Use of a laboratory flume system allowed steady stream flow conditions to be maintained throughout both experiments, and alternating injections of known quantities of kaolinite and a sodium chloride tracer were used to assess the effect of clay accumulation on hyporheic exchange directly. In the first experiment, there was no bed sediment transport and kaolinite deposition formed a highly clogged near‐surface layer that greatly reduced hyporheic exchange. Application of a fundamental model for advective hyporheic exchange indicated that the effective permeability and porosity of the streambed decreased substantially during the course of the experiment. In the second experiment, the kaolinite was prepared with different surface properties to be more mobile, and the experiment was conducted with a small degree of bed sediment transport. As a result, no distinct clogged layer developed, and the rate of hyporheic exchange was found to remain approximately constant throughout the experiment (29 days). These results indicate that increasing fine sediment loads, e.g. those that occur from changes in land use, can have substantially different impacts on hyporheic exchange and associated ecological processes depending on the stream flow conditions, the rate and frequency of bed sediment transport, and the extent of interaction of the introduced fines with bed sediments. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   

Aggregate performance in managing marine ecosystems of 53 maritime countries     

Jacqueline Alder  Sarika Cullis-Suzuki  Vasiliki Karpouzi  Kristin Kaschner  Suzanne Mondoux  Wilf Swartz  Pablo Trujillo  Reg Watson  Daniel Pauly 《Marine Policy》2010

Fourteen indicators of marine living resource management performance by country, reflecting both their intention to sustainably use the resource within their Exclusive Economic Zones and the effectiveness of their policies, were developed and the performances of 53 maritime countries were assessed. Four rankings of the countries, which jointly account for over 95 percent of the world's marine fisheries landings, are presented here as aggregated scores of the fourteen indicators, using different schemes for weighting the indicators, each reflective of the management preferences identified by the Global Environment Outlook 4 (GEO4) future development scenarios: Market First; Policy First; Security First; and Sustainability First. The resulting rankings differed substantially between the weighting schemes for the top performing countries but less so for the countries performing poorly.  相似文献   

Global earthquake casualties due to secondary effects: a quantitative analysis for improving rapid loss analyses   总被引：1，自引：0，他引：1  

Kristin D. Marano  David J. Wald  Trevor I. Allen 《Natural Hazards》2010,52(2):319-328

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Physics of the Omori law: Inferences from interevent time distributions and pore pressure diffusion modeling     

Mattias Lindman  Bjrn Lund  Roland Roberts  Kristin Jonsdottir 《Tectonophysics》2006,424(3-4):209

Empirical laws and statistics of earthquakes are valuable as a basis for a better understanding of the earthquake cycle. In this paper we focus on the postseismic phase and the physics of aftershock sequences. Using interevent time distributions for a catalogue of Icelandic seismicity, we infer that the parameter C₂ in the Omori law, often considered to represent incomplete detection of aftershocks, is at least in part related to the physics of the earthquake process. We investigate the role of postseismic pore pressure diffusion after two Icelandic earthquakes on the rate of aftershocks and what we can infer about the physical meaning of C₂ from the diffusion process. Using the Mohr–Coulomb failure criterion we obtain a rate of triggered points in our diffusion model that agrees with the modified Omori law, with a value of C₂ that is consistent with data. Our pore pressure diffusion model suggests that C₂ is related to the process of reducing high pore pressure gradients existing across a fault zone at short times after a main shock.  相似文献   

Bacterial responses in activity and community composition to photo-oxidation of dissolved organic matter from soil and surface waters   总被引：1，自引：0，他引：1  

Kristin E. Judd  Byron C. Crump  George W. Kling 《Aquatic Sciences - Research Across Boundaries》2007,69(1):96-107

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