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541.
Muhammad BASHARAT Joachim ROHN Mirza Shahid BAIG Muhammad Rustam KHAN Markus SCHLEIER 《山地科学学报》2014,11(1):19-30
The SPOT image analysis in Muzaffarabad Azad Kashmir,northwest Himalayas,Pakistan reveals that the Kashmir earthquake 2005 triggered a number of coseismic mass movements along the hanging wall block of the Muzaffarabad Fault.The Neelidandi and Langarpura rock falls have been identified as two major reactivated mass movements with an estimated volume of 3.1 × 106m3and 5.76 × 106m3,respectively.The Neelidandi and Langarpura mass movements were initiated during earthquake in the direction of northwest-southeast extension and northeastsouthwest directed thrusting,respectively.The Neelidandi rock fall occurred in sheared cherty dolomites and limestones of the Cambrian Muzaffarabad Formation,whereas the Langarpura rock fall occurred in alternating clays,shales,claystones,siltstones and sandstones of the Miocene Murree Formation.These rock units along the fault are highly fractured and jointed.The geotechnical maps and geological longitudinal profiles show the relationship between the geometrical characteristics and mechanism of these mass movements.Their characteristics were analyzed according to the role of topographic,seismic,geological and tectonic factors.The steep topography,sheared rocks,lithology,coseismic uplift and strong ground shaking of the hanging wall block along Muzaffarabad Fault facilitated the gravity collapse of these mass movements. 相似文献
542.
Phosphorus (P) and other chemical elements have been used to identify residential middens at archaeological sites. This study discusses the relationship of soil chemical elements and middens at Group Chispa, a Late Classic residential complex at a commoner village in the Maya lowlands. The complex was extensively excavated and soil sampled. Ceramic sherd densities, which serve as a proxy for artifact densities, correlate only partially with phosphorus and other chemical elements. One of the three middens in Group Chispa coincides with the highest concentration of P while the two others—including the most extensive one—have medium to low P levels. A spectrum of human activities that include the preparation of pigments explains the nontraditional distribution of chemical elements. High P levels remain useful to detect middens but they provide an incomplete picture and need to be contextualized by comprehensive archaeological data. 相似文献
543.
Hydration/dehydration of water-active rocks under non-isothermal conditions is encountered in many industries, in particular
the drilling industry. Water-active rocks can adsorb water on their basal crystal surfaces on both the external, and, in the
case of expanding lattice clays, the inter-layer surfaces. There are two main mechanisms in which the instability may occur
for a structure built in water-active rocks. First mechanism is the change in stresses resulted from mechanical, hydraulic,
chemical and thermal interaction, which we formulate based on the concept of non-equilibrium thermodynamics. Second mechanism
illustrates the change in mechanical properties of the rock due to physic-chemical interaction between the rock and exposed
fluid. We postulate the later mechanism in terms of chemically active plastic deformation by using the modified Cam Clay model.
The complete governing equations for non-isothermal chemo-poro-elastoplastic rock are therefore presented. A three-dimensional
finite element model is then developed to solve the obtained governing equations. From the numerical results, it was found
that the effect of temperature coupling term on stress cannot be ignored when non-isothermal conditions are encountered. However,
this effect is almost trivial on pore pressure. It was also revealed that the effect of change in the shale’s mechanical properties
on stability due to physic-chemical interaction is as important as change in stresses due to mechanical, hydraulic, chemical
and thermal interactions. 相似文献
544.
Mineral-organic associations act as mediators of litter-derived N flow to the mineral soil, but the time scales and pathways involved are not well known. To close that gap, we took advantage of decade old 15N litter labeling experiments conducted in two European forests. We fractionated surface soils by density with limited disaggregating treatment and investigated organic matter (OM) characteristics using δ13C, δ15N and the C/N ratio. Mineral properties were studied by X-ray diffraction and selective dissolution of pedogenic oxides.Three types of associations were isolated: plant debris with few trapped minerals (<1.65 g/cm3), aggregates dominated by phyllosilicates (1.65-2.4 g/cm3), and single mineral grains and pedogenic oxides with little OM (>2.4 g/cm3). A small proportion of 15N tracer was rapidly attached to single mineral grains, while most of it moved from plant debris to aggregates of low density and progressively to aggregates of higher density that contain a more microbially processed OM. After a decade, 60% of the 15N tracer found in the investigated horizon was retained in aggregates, while plant debris still contained 40% of the tracer.We present a conceptual model of OM and N flow through soil mineral-organic associations, which accounts for changes in density, dynamics and chemistry of the isolated structures. It suggests that microbial reworking of OM entrapped within aggregates (1.65-2.4 g/cm3) causes the gradient of aggregate packing and, further on, controls the flow of litter-derived N through aggregates. For associations with denser material (>2.4 g/cm3), mineralogy determines the density of the association, the type of patchy OM attached to mineral surfaces and controls the extent of litter-derived N incorporation. 相似文献
545.
Despite the long tradition of technical mitigation on a catchment scale in European mountain regions, losses due to mountain
hazards are still considerably high in number and monetary loss. Therefore, the concept of technical mitigation had been supplemented
by land-use planning and, more recently, local structural protection. Local structural protection includes measures directly
implemented at or adjacent to endangered objects, and has proven to be particularly cost-effective with respect to integral
risk management strategies. However, the effect of local structural protection in reducing the vulnerability of elements at
risk, and the associated consequences with respect to a reduction of structural vulnerability have not been quantified so
far. Moreover, there is a particular gap in quantifying the expenditures necessary for local structural protection measures.
Therefore, a prototype of residential building adapted to mountain hazards is presented in this study. This prototype is equipped
with various constructional elements to resist the incurring impact forces, i.e., of fluvial sediment transport and of snow
avalanches. According to possible design loads emerging from these hazard processes, the constructive design necessary is
presented, and the amount of additional costs required for such an adaptation is presented. By comparing these costs with
quantitative loss data it is shown that adapted building design is particularly effective to reduce the consequences of low-magnitude,
high-frequency events in mountain regions. 相似文献
546.
547.
Hundreds of natural catastrophes occur worldwide every year—there were 780 loss events per year on average over the last 10 years. Since 1980, these disasters have claimed over two million lives and caused losses worth US$ 3,000 billion. The deadliest disasters were caused by earthquakes: the tsunami following the Sumatra quake (2004) and the Haiti earthquake (2010) claimed more than 220,000 lives each. The Great East Japan Earthquake of 11 March 2011 was the costliest natural disaster of all times, with total losses of US$ 210 billion. Hurricane Katrina, in 2005, was the second costliest disaster, with total losses of US$ 140 billion (in 2010 values). To ensure that high-quality natural disaster analyses can be performed, the data have to be collected, checked and managed with a high degree of expertise and professionality. Scientists, governmental and non-governmental organisations and the finance industry make use of global databases that contain losses attributable to natural catastrophes. At present, there are three global and multi-peril loss databases: NatCatSERVICE (Munich Re), Sigma (Swiss Re) and EM-Dat (Centre for Research on the Epidemiology of Disasters). They are supplemented by numerous databases focusing on national or regional issues, certain hazards and specific sectors. This paper outlines the criteria and definitions relating to how global and multi-peril databases are operated, and the efforts being made to ensure consistent and internationally recognised standards of data management. In addition, it presents the concept and methodology underlying the NatCatSERVICE database, and points out the many challenges associated with data acquisition and data management. 相似文献
548.
Christoph Haase Andreas Dahmke Markus Ebert Dirk Schäfer Frank Dethlefsen 《Aquatic Geochemistry》2014,20(6):639-661
Among the risks of CO2 storage is the potential of CO2 leakage into overlaying formations and near-surface potable aquifers. Through a leakage, the CO2 can intrude into protected groundwater resources, which can lead to groundwater acidification followed by potential mobilisation of heavy metals and other trace metals through mineral dissolution or ion exchange processes. The prediction of pH buffer reactions in the formations overlaying a CO2 storage site is essential for assessing the impact of CO2 leakages in terms of trace metal mobilisation. For buffering the pH-value, calcite dissolution is one of the most important mechanisms. Although calcite dissolution has been studied for decades, experiments conducted under elevated CO2 partial pressures are rare. Here, the first study for column experiments is presented applying CO2 partial pressures from 6 to 43 bars and realising a near-natural flow regime. Geochemical calculations of calcite dissolution kinetics were conducted using PHREEQC together with different thermodynamic databases. Applying calcite surface areas, which were previously acquired by N2-BET or calculated based on grain diameters, respectively, to the rate laws according to Plummer et al. (Am J Sci 278:179–216, doi:10.2475/ajs.278.2.179, 1978) or Palandri and Kharaka (US Geol Surv Open file Rep 2004–1068:71, 2004) in the numerical simulations led to an overestimation of the calcite dissolution rate by up to three orders of magnitude compared to the results of the column experiments. Only reduction of the calcite surface area in the simulations as a fitting procedure allowed reproducing the experimental results. A reason may be that the diffusion boundary layer (DBL), which depends on the groundwater flow velocity and develops at the calcite grain surface separating it from the bulk of the solution, has to be regarded: The DBL leads to a decrease in the calcite dissolution rate under natural laminar flow conditions compared to turbulent mixing in traditional batch experiments. However, varying the rate constants by three orders of magnitudes in a field scale PHREEQC model simulating a CO2 leakage produced minor variations in the pH buffering through calcite dissolution. This justifies the use of equilibrium models when calculating the calcite dissolution in CO2 leakage scenarios for porous aquifers and slow or moderate groundwater flow velocities. However, the selection of the thermodynamic database has an impact on the dissolved calcium concentration, leading to an uncertainty in the simulation results. The resulting uncertainty, which applies also to the calculated propagation of an aquifer zone depleted in calcite through dissolution, seems negligible for shallow aquifers of approximately 60 m depth, but amounts to 35 % of the calcium concentration for aquifers at a depth of approximately 400 m. 相似文献
549.
A geological database for parameterization in numerical modeling of subsurface storage in northern Germany 总被引:1,自引:0,他引:1
Underground land use can play a significant role in future concepts of energy and gas storage and requires an improved understanding of the parameters of potential storage formations (saline aquifers), for instance of porosity and permeability, and also of mineralogical and gas compositions. This study aims at providing data examples and calculating vertical spatial variations through variogram analyses of important North German geological reservoirs from Dogger, Rhaetian, Middle Buntsandstein, and Rotliegend (Sub)Groups and Formations, focusing on the western part of the North German Basin. Vertical correlation lengths of porosity and permeability data range between 0 and 30 m, while most results are calculated at approximately 2–4 m and do not show relevant differences among the evaluated formations. In the majority of the regarded formations, the Kozeny–Carman relationship between porosity and permeability is supported as long as low porosity and permeability values are excluded from the evaluation. Mineral percentages varied significantly among the evaluated sediments. Besides quartz, ankerite is the main compound in the Dogger Group, while feldspars and clay minerals were more frequent in the Rhaetian, Middle Buntsandstein, and Rotliegend sediments. Methane was the main gas compound in the reservoirs, followed by nitrogen, ethane, and carbon dioxide. This study serves as preparatory work to allow for the parameterization of geological models and a subsequent simulation of fluid transport to evaluate (long-term) safety and impacts of geothermal and gas storage projects. 相似文献
550.
Homogeneous reprocessing of GPS,GLONASS and SLR observations 总被引:3,自引:2,他引:1
Mathias Fritsche Krzysztof Sośnica Carlos Javier Rodríguez-Solano Peter Steigenberger Kan Wang Reinhard Dietrich Rolf Dach Urs Hugentobler Markus Rothacher 《Journal of Geodesy》2014,88(7):625-642
The International GNSS Service (IGS) provides operational products for the GPS and GLONASS constellation. Homogeneously processed time series of parameters from the IGS are only available for GPS. Reprocessed GLONASS series are provided only by individual Analysis Centers (i. e. CODE and ESA), making it difficult to fully include the GLONASS system into a rigorous GNSS analysis. In view of the increasing number of active GLONASS satellites and a steadily growing number of GPS+GLONASS-tracking stations available over the past few years, Technische Universität Dresden, Technische Universität München, Universität Bern and Eidgenössische Technische Hochschule Zürich performed a combined reprocessing of GPS and GLONASS observations. Also, SLR observations to GPS and GLONASS are included in this reprocessing effort. Here, we show only SLR results from a GNSS orbit validation. In total, 18 years of data (1994–2011) have been processed from altogether 340 GNSS and 70 SLR stations. The use of GLONASS observations in addition to GPS has no impact on the estimated linear terrestrial reference frame parameters. However, daily station positions show an RMS reduction of 0.3 mm on average for the height component when additional GLONASS observations can be used for the time series determination. Analyzing satellite orbit overlaps, the rigorous combination of GPS and GLONASS neither improves nor degrades the GPS orbit precision. For GLONASS, however, the quality of the microwave-derived GLONASS orbits improves due to the combination. These findings are confirmed using independent SLR observations for a GNSS orbit validation. In comparison to previous studies, mean SLR biases for satellites GPS-35 and GPS-36 could be reduced in magnitude from \(-35\) and \(-38\) mm to \(-12\) and \(-13\) mm, respectively. Our results show that remaining SLR biases depend on the satellite type and the use of coated or uncoated retro-reflectors. For Earth rotation parameters, the increasing number of GLONASS satellites and tracking stations over the past few years leads to differences between GPS-only and GPS+GLONASS combined solutions which are most pronounced in the pole rate estimates with maximum 0.2 mas/day in magnitude. At the same time, the difference between GLONASS-only and combined solutions decreases. Derived GNSS orbits are used to estimate combined GPS+GLONASS satellite clocks, with first results presented in this paper. Phase observation residuals from a precise point positioning are at the level of 2 mm and particularly reveal poorly modeled yaw maneuver periods. 相似文献