震前卫星热红外环形应力场特征   总被引：6，自引：1，他引：5  

强祖基  姚清林  魏乐军  赵勇  郭坚峰  曾佐勋  谢红接 《地球学报》2008,29(4):486-494

本文包括两部分内容:①描述了1996年2月3日云南丽江Ms7.0级地震,震前几天的卫星热红外图像呈现圆形,它的NNW、NW、SN、及NE向的热旋扭面往S收敛。该地震地表破裂由一系列张扭性裂缝组成,呈左旋左列,水平位错不明显,垂直断距数厘米。垂直力对构造变动的作用较为明显;而丽江地震震源机制解破裂面II的走向NNE6o,倾向W,倾角44o,P轴方位为NNE3o、仰角75o,近于直立,综合热旋扭面展布、地震地表破裂特征及震源机制解,得出该旋扭椭圆为地幔外侧右旋上涌所造成;②菲律宾萨马岛Ms7.0～7.5强震群及青海共和Ms7.0地震前热应力环椭圆的推进路径。根据这一特征得出交变潮汐力的地球动力学解释。卫星热红外图像震前应力热场的方法是临震预测地震的有效方法,卫星热红外技术辅以震源机制解和地表破裂带力学分析是研究地球动力学有力工具。地球自转速度变化,交变潮汐力和地幔旋扭上涌力是地球动力学的主因。  相似文献   

Characterizing groundwater flow in a faulted karst system using optical brighteners from septic systems as tracers     

K. E. Murray  D. R. Straud  W. W. Hammond 《Environmental Geology》2007,53(4):769-776

This study used optical brighteners (OB) released from septic systems to show that groundwater flow direction is largely controlled by the structural framework in a faulted karst groundwater system. Effective protection of groundwater resources requires that groundwater systems are adequately characterized and source water protection areas (SWPA) are developed for drinking water wells. Karst aquifers are among the most sensitive to contamination due to high recharge rates, and among the most difficult aquifers to characterize due to heterogeneity, and anisotropy. Because septic systems may be used to treat wastewater within SWPAs for karst aquifers there is a need to characterize these groundwater systems using tracers. The objective of this study was to characterize groundwater flow in a faulted portion of the Edwards aquifer in Bexar County, Texas using OB that are released as incidental tracers from septic systems. This study included measurement of water levels, sampling of groundwater and surface water, analysis for OB, and spatial analysis in a GIS. Results show that OB intensities were highest to the southwest of the septic area, a direction that is sub-parallel to the fault and fracture orientation and nearly perpendicular to the hydraulic gradient. This indicates that movement of OB, solutes, or non-aqueous liquids/solids in a faulted karst system can be largely controlled by fault/fracture orientation and structural relay ramps.  相似文献   

Environmental geology     

Peter T. Flawn 《Environmental Geology》1975,1(1):3-4

  相似文献   

Sulphate efflorescences at the geyser near Pinchollo,southern Peru     

《Journal of South American Earth Sciences》2013

Sulphate mineralization precipitated around a geyser located above the village of Pinchollo, Chivay district and below Hualca Hualca volcano (6025 m a.s.l.) in the Western Cordillera of southern Peru is described. The geyser is one of many manifestations of thermal activity in the Arequipa department. Its age is estimated to be Upper Pleistocene–Holocene, as the discharge point lies at the intersection of a fault system with latitudinal dip-slip fault cutting a volcanic-debris avalanche of probably Pleistocene age. Thermal waters present in the Chivay district are mainly chloride-rich with a neutral pH. They are rich in Li, Sr, and B. The water erupting in the geyser boils at about 85 °C, as it lies at some 4353 m a.s.l.The minerals examined, of various habits and various yellow, orange and white colours were precipitated on the soil and on plants close to the geyser (location 1), on the walls of a 1 m diameter pothole filled with boiling water (location 1a) and at a distance of some 100 m to the west of the geyser (location 2). All are sulphates. Their chemical composition is fairly simple, consisting of Al, Fe, K, Mg, Ca, S, NH₄ and O, and all display chemical zoning. But the phase composition is more complex. In all locations, alunogene, copiapite, coquimbite, tschermigite and gypsum are present. Close to the geyser (location 1) magnesium-containing sulphates, namely, boussingaultite and pickeringite also occur. Iron sulphates such as mohrite and rozenite precipitate on the walls of the pothole (location 1a). Sulphates containing potassium such as jarosite, alunite and voltaite–voltaite (Mg) dominate among the efflorescences in location 2, where hematite was also noted. Any quartz and kaolinite or illite/mica admixture identified in some samples derives from adjacent soil.The present geothermal system does not involve the deposition of precious-metal deposits such as those associated with an earlier deep-going epithermal system that scavenged a large volume of rock. Most likely, as the present-day thermal waters do not involve a juvenile-water component, the geyser waters derive from a shallower source.  相似文献   

An evaluation of the exposure in nadir observation of the JEM-EUSO mission     

《Astroparticle Physics》2013

We evaluate the exposure during nadir observations with JEM-EUSO, the Extreme Universe Space Observatory, on-board the Japanese Experiment Module of the International Space Station. Designed as a mission to explore the extreme energy Universe from space, JEM-EUSO will monitor the Earth’s nighttime atmosphere to record the ultraviolet light from tracks generated by extensive air showers initiated by ultra-high energy cosmic rays. In the present work, we discuss the particularities of space-based observation and we compute the annual exposure in nadir observation. The results are based on studies of the expected trigger aperture and observational duty cycle, as well as, on the investigations of the effects of clouds and different types of background light. We show that the annual exposure is about one order of magnitude higher than those of the presently operating ground-based observatories.  相似文献   

Simulated various characteristic waves in acoustic full waveform relating to cement bond on the secondary interface     

Hongbing Zhang  Danyan Xie  Zuoping Shang  Xuebing Yang  Hongjian Wang  Honggen Tao 《Journal of Applied Geophysics》2011,73(2):139-154

Bad cement bond with water channeling or low strength cement is usually generated on the first and/or secondary interfaces which lie between the cement and casing, and the cement and formation, respectively. It is an inherently complicated problem to evaluate cement bond on the secondary interface (SICB) in a cased borehole. So we need to find a useful wave for evaluating SICB and provide its propagation features. To achieve this, we simulated the acoustic full waveform, 2-D spectrum and dispersion curves in cased boreholes based on the real axis integration method, and a propagator matrix. Simulation results indicated that “casing-cement mode” wave can be utilized to evaluate SICB, as it is most sensitive to water channeling on the secondary interface. Velocity of this mode wave is in between that of the casing wave and the formation wave, so that it is easy to extract it in time. The dispersion curves showed that the casing-cement wave is a dispersion wave, but not a pseudo-Rayleigh wave. Its velocity is obviously larger than v_s of cement. Simulation results further indicated that the amplitude of casing-cement wave is decreasing with increasing cement sheath thickness, but not water channeling thickness, and its travel time is influenced by casing and cement together. Moreover, we investigated factors influencing the casing–cement wave and found that casing diameter and peak frequency are major factors influencing the amplitude and the travel time, while other factors, such as P-wave velocities of cement and wall thickness of casing, are minor factors. But none of these factors greatly influence bond index which is computed from the amplitude. So the bond index has an advantage over the amplitude during evaluating SICB. Formation wave is a helpful signal to evaluate low strength cement without water channeling, and its amplitude is mainly related to the velocities (or impedances) of both cement and formation except for formation attenuation and disturbance wave. Experimental data in calibration pits and field data detecting channeling demonstrated the simulation results.  相似文献   

Dusty roads and disconnections: Perceptions of dust from unpaved mining roads in Mongolia’s South Gobi province     

《Geoforum》2015

South Gobi province is at the center of Mongolia’s mining boom, where companies began exporting minerals over dirt-track roads in the early 2000s. This paper examines recent controversies surrounding road dust near the Oyu Tolgoi copper–gold mine, the so-called coal road from Tavan Tolgoi mines, and the Chinese border. At the time of the research, local residents, particularly nomadic herders, were concerned that dust produced from unpaved mining roads was coating the pasture, causing illnesses among livestock, and endangering their livelihoods in the region. The presence of dust rendered mining an uncomfortably intimate experience as state and corporate actors negotiated responsibility for infrastructure development. The paper builds on the concept “technologies of distantiation” to reveal the complex ways that dust from unpaved roads creates distances and disconnections between people, livelihoods, and landscapes, representing an enclosure of the pasture. Methods for the paper include interviews, focus groups, and participant observation conducted in South Gobi province and Ulaanbaatar in 2010, 2011, and 2012 as well as follow-up research carried out in spring 2015.  相似文献   

Middle atmosphere polar warmings on Mars: Simulations and study on the validation with sub-millimeter observations     

《Planetary and Space Science》2007,55(9):1103-1112

Temperature inversions and the warmings over the winter poles in the Martian atmosphere occur due to the adiabatic heating associated with the downward branch of the Hadley circulation. We present results of simulations with a recently developed GCM which suggest that the warmings are the manifestations of the global meridional transport, and are strongly related to atmospheric eddies (planetary waves and tides). To date, sets of data required for the validation of the predicted warmings and the corresponding circulation patterns do not extend far enough into the middle atmosphere of Mars. This motivated our radiative and retrieval simulations to demonstrate that sub-millimeter observations can provide the required fields to validate and constrain the GCM results.  相似文献   

On aliasing Rossby waves induced by asynchronous time stepping     

《Ocean Modelling》2003,5(1):65-76

The errors introduced by asynchronous time stepping are analyzed. It is shown that asynchronous time stepping distorts the structure and the speed of the lowest mode. For typical time step ratios used in climate simulations, the lowest mode is no longer a strictly barotropic mode, and the associated wave is much slower than the barotropic Rossby waves in the oceans. As a result, seasonal cycles simulated in model runs based on asynchronous time stepping are severely contaminated.  相似文献   

Chemical reactions and porosity changes during sedimentary diagenesis     

《Applied Geochemistry》2002,17(1):39-47

It is of interest to simulate the porosity changes associated with fluid flow and water–rock reactions in sedimentary systems. The chemical species taken into account are: {H₂O, H⁺, Ca⁺⁺, HCO₃⁻, Mg⁺⁺, Al(OH)₄⁻, H₄SiO₄, K⁺, Na⁺, Cl⁻}. The solution is assumed to be locally at equilibrium with different mineral assemblages including at least calcite, dolomite and one Mg–Al-silicate. These assemblages buffer the partial pressure of CO₂ (Pco₂ ) which increases with temperature (T) as is commonly observed in natural systems. The nature of the Mg–Al-silicate and the presence or absence of other at-equilibrium minerals (i.e. the feldspars) do not modify the Pco₂–T relationship. Considering complete transfer between the solution and the solid phases, computed relative porosity increases with increasing temperature for all the systems that were investigated. However, the direction and the amount of the clay transfer depend on the presence of feldspars. Furthermore, it is shown that computing mass transfer using a prescribed Pco₂, as is commonly done, leads to very different values of mineral transfers. Hence, it must be concluded that prescribing a Pco₂ value, even if the proper Pco₂–T relationship is used, leads to erroneous results.  相似文献