Role of fluids in surface deformation caused by the 1999 Chi‐Chi earthquake in Taiwan     

Jiin‐Shuh Jean  Chuan‐Cheng Liu  Wei‐Teh Jiang  Jinder Chow  Ting‐To Yu  Ching‐Weei Lin  Shih‐Wei Huang 《地球表面变化过程与地形》2002,27(1):1-10

The 1999 Chi‐Chi earthquake significantly altered the landscape of central Taiwan. Surface deformation produced by the earthquake along the trace of the Chelungpu thrust can be classified into two styles: (1) uplift without significant surface rupture, and (2) uplift accompanied by surface rupture. Here we examine areas that exhibited the first style of deformation (e.g. Wufeng). Seismic stress at the time of the main shock may have been relieved by high pore‐fluid pressure in a 300‐m‐thick sand and gravel aquifer. Along the thrust fault, frictional heating of these sediments resulted in thermal expansion and an increase in pore‐fluid pressure. High pore‐fluid pressure damped seismic‐wave energy and enhanced intergranular slips of unconsolidated sandy and gravel sediments, which were possibly assisted by sulphuric acid corrosion, leading to a high sulphate content in the groundwater (c. 70 mg L^?1). These changes permitted surface folding and terrace‐style uplifting to occur without significant rupture. In contrast, other areas in which the second style of deformation is dominant (e.g. Fengyuen‐Shihkang) have thin (0–10 m) sand and gravel deposits and lower concentrations of sulphate (c. 30 mg L^?1) in groundwater. In these areas, sediments were heated but not sufficiently to produce significant thermal expansion and increase in pore‐fluid pressure; accumulation of stress in these locations led to rupture at the ground surface, with the formation of steep fault scarps. The areas exhibiting the first deformation style are characterized by the presence of high pore‐fluid pressure, frictional heat conduction, and possibly chemical corrosion related to sulphuric acid attack and formation of sulphate, in contrast to those involving significant uplift and surface rupture. The areal distribution of these two surface deformation styles suggests that the aforementioned fluid‐related subsurface processes may have altered the characteristics of sediments and caused diverse responses to the quake. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   

Simulation of Meteorological Fields Within and Above Urban and Rural Canopies with a Mesoscale Model   总被引：3，自引：4，他引：3  

Sylvain Dupont  Tanya L. Otte  Jason K. S. Ching 《Boundary-Layer Meteorology》2004,113(1):111-158

Accurate simulation of air quality at neighbourhood scales (on order of 1-km horizontal grid spacing) requires detailed meteorological fields inside the roughness sub-layer (RSL). Since the assumptions of the roughness approach, used by most of the mesoscale models, are unsatisfactory at this scale, a detailed urban and rural canopy parameterisation, called DA-SM2-U, is developed inside the Penn State/NCAR Mesoscale Model (MM5) to simulate the meteorological fields within and above the urban and rural canopies. DA-SM2-U uses the drag-force approach to represent the dynamic and turbulent effects of the buildings and vegetation, and a modified version of the soil model SM2-U, called SM2-U(3D), to represent the thermodynamic effects of the canopy elements. The turbulence length scale is also modified inside the canopies. SM2-U(3D) assesses the sensible and latent heat fluxes from rural and urban surfaces in each of the computational layers inside the canopies by considering the shadowing effect, the radiative trapping by the street canyons, and the storage heat flux by the artificial surfaces. DA-SM2-U is tested during one simulated day above the city of Philadelphia, U.S.A. It is shown that DA-SM2-U is capable of simulating the important features observed in the urban and rural RSL, as seen in the vertical profiles of the shear stress, turbulent kinetic energy budget components, eddy diffusivity, potential air temperature, and specific humidity. Within the canopies, DA-SM2-U simulates the decrease of the wind speed inside the dense canopies, the skirting of the flow around the canopy blocks, warmer air inside the vegetation canopy than above open areas during the night and conversely during the day, and constantly warmer air inside the urban canopy. The comparison with measurements shows that the surface air temperature above rural and urban areas is better simulated by DA-SM2-U than by the `standard version' of MM5.  相似文献   

Ductile deformation and regional strain field in the southern segment of the Tancheng-Lujiang fault zone,eastern China     

Jiawei Xu  Ping Wang  Rengao Ching  Zhoujie Ye 《Pure and Applied Geophysics》1986,124(1-2):337-364

Studies in a segment of the Tancheng-Lujiang fault zone show that it is a major transcurrent ductile shear zone with a considerable sinistral displacement. The formations (PtT₁₊₂) at depths of 5 to 15 km may have cropped out in this area during subsequent erosion. Many ductilely deformed structures are in it. The deformed zone was formed during the Indo-Sinian orogeny. On the basis of measurements and analyses of many deformed pebbles within the shear zone, it is suggested that the deformation in the zone studied may be catagorized as a variation of simple shear and plane strain with a constant volume. The intensely deformed belt is generally 40 to 50 km wide, with the average strain ratio 27.68 and the maximum greater than 87.37. From analysis of elongation strain, we estimate that the deformed belt has been elongated by 164.23 km and narrowed by 222.5 km. The internal belt was formed by a high shear strain , calculated to be more than 11.34. The deformed belt is associated with syntectonic dynamothermal metamorphism, represented by greenschist facies and retrogressive metamorphism on previous amphibolite facies.  相似文献   

Urban-scale variations of turbulence parameters and fluxes     

Ching  J. K. S. 《Boundary-Layer Meteorology》1985,33(4):335-361

Sensible heat (H) and latent heat (LE) fluxes and turbulence statistics in St. Louis, Missouri and the surrounding region are presented. The urban-scale analyses were derived from a series of aircraft transects at 150 m above ground across the metropolitan area during the afternoon convective period. The results revealed that H varied by a factor of two to four in the region; the largest values were associated with the urban heat island. LE varied across the urban area by about a factor of four, but low values of LE overlaid the urban heat island. Consequently, the Bowen ratio (H/LE) exhibited large spatial variability, with a maximum value greater than 1.5 over the city and values less than 0.2 in nonurban areas. The areas along the Mississippi River and adjacent low lying marshland northeast of the downtown area displayed significantly smaller H and Bowen ratio. The derived surface heat storage term (G) for this area as well as for the urban area exceeded either H or LE.The spatial patterns for the standard deviations of the three velocity components ( _u,v,w ), temperature ( _T ), and absolute humidity ( _q ), are also presented. The patterns of _u,v,w were similar to the pattern of H. the highest values associated with the urban heat island. The correlation coefficient between the vertical velocity and temperature fluctuations was highest over the city, and a noteworthy minimum was observed in the upwind area over the river and marshland in association with low H. The convective similarity relationships for _u,v,w appeared to be approximately valid spatially, as variations were typically less than 10% from theory over the urban area and nonurban region, except for a 40% anomaly in the lowland around the river northeast of the city.Measurements of H from 30-m towers within various land-use areas were contrasted with the aircraft data. Land-use differences in H at the surface were at least as large as those observed at 150 m across the city. This was primarily because of the measurement requirement that the minimum resolvable fetch increases with measurement height.  相似文献   

Parameterization of subsurface heating for soil and concrete using net radiation data   总被引：2，自引：0，他引：2  

Dennis Doll  J. K. S. Ching  Jack Kaneshiro 《Boundary-Layer Meteorology》1985,32(4):351-372

The variability of surface sensible heat flux depends strongly on the heating rate of the material beneath the surface. This variability is expected to be large in urban areas where the surfaces are layered with a variety of man-made materials. Parameterization of the ground heat storage as a function of surface materials is presented based on analyses of data obtained during the U.S. Environmental Protection Agency's Regional Air Pollution Study conducted in St. Louis, Missouri. Ground heat flux data are derived from observations of surface and subsurface temperatures for a soil layer and for concrete slabs resting on soil. The data show that the presence of the concrete slabs increases the ground storage term relative to that for soil alone. The ground storage and sensible heat flux terms for a blackened concrete slab are larger than for an unpainted concrete slab. For the concrete surfaces, the ratio of ground storage to net radiation is >1 at night and <1 during the day. This ratio is discontinuous at sunrise and sunset transition periods. For soil, the ratio shows similar temporal behavior except that on average, there is a smoother transition at sunrise. Simple mathematical expressions giving the ratio of ground heat storage to net radiation as a function of time are presented.Now with Enviroplan, Incorporated, West Orange, NJ 07052, U.S.A.On assignment from the National Oceanic and Atmospheric Administration, U.S. Department of Commerce.  相似文献   

Big data and machine learning in geoscience and geoengineering: Introduction     

Wengang Zhang  Jianye Ching  Anthony T.C.Goh  Andy Y.F.Leung 《地学前缘(英文版)》2021,12(1):327-329

In recent years,we have entered the so-called Fourth Paradigm with the regular production of huge amount of observational data.Big data is often characterized by the three‘V's:Volume of data,Variety and Velocity.The concept of big data can potentially address some existing issues in areas of geoscience and geoengineering.Large-scale,comprehensive,multidirectional and multifield geotechnical monitoring is becoming a reality in the very near future.  相似文献   

Energy equation and stress–dilatancy relationship for sand     

Chang  Ching S.  Deng  Yibing 《Acta Geotechnica》2022,17(7):2675-2696

The energy equation is an expression of the first law of thermodynamics or the law of conservation of energy. According to the first law of thermodynamics, the externally applied work to a system is equal to the sum of dissipation energy and Helmholtz free energy of the system. However, most of the currently available stress–dilatancy relationships are based on the energy equation of Taylor-Cam Clay type, which hypothesizes that the applied plastic work is equal solely to the frictional dissipation energy. The Helmholtz free energy has been completely neglected. Recently, observed from acoustic experiments, it has been recognized that Helmholtz free energy can be caused by deformation mechanisms other than friction between particles. Thus, it is necessary to include additional terms in the energy equation in order to correctly model the stress-dilatancy behavior. This paper addresses the issue regarding the balance of this energy equation. Analyses of experimental results are presented. Specific forms of the frictional energy and Helmholtz free energy are proposed. The proposed energy equation is verified with the experimental data obtained from Silica sand, Ottawa sand, and Nevada sand.

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Use of slow-release fertilizer and biopolymers for stimulating hydrocarbon biodegradation in oil-contaminated beach sediments   总被引：4，自引：0，他引：4  

Xu R  Yong LC  Lim YG  Obbard JP 《Marine pollution bulletin》2005,51(8-12):1101-1110

Nutrient concentration and hydrocarbon bioavailability are key factors affecting biodegradation rates of oil in contaminated beach sediments. The effect of a slow-release fertilizer, Osmocote, as well as two biopolymers, chitin and chitosan, on the bioremediation of oil-spiked beach sediments was investigated using an open irrigation system over a 56-day period under laboratory conditions. Osmocote was effective in sustaining a high level of nutrients in leached sediments, as well as elevated levels of microbial activity and rates of hydrocarbon biodegradation. Chitin was more biodegradable than chitosan and gradually released nitrogen into the sediment. The addition of chitin or chitosan to the Osmocote amended sediments enhanced biodegradation rates of the alkanes relative to the presence of Osmocote alone, where chitosan was more effective than chitin due to its greater oil sorption capacity. Furthermore, chitosan significantly enhanced the biodegradation rates of all target polycyclic aromatic hydrocarbons.  相似文献   

Effects of fishing on the structure and functioning of estuarine and nearshore ecosystems   总被引：9，自引：0，他引：9  

Blaber  S. J. M.; Cyrus  D. P.; Albaret  J.-J.; Ching  Chong Ving; Day  J. W.; Elliott  M.; Fonseca  M. S.; Hoss  D. E.; Orensanz  J.; Potter  I. C.; Silvert  W. 《ICES Journal of Marine Science》2000,57(3):590-602

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Spatial correlation for transformation uncertainty and its applications     

Jianye Ching  Kok-Kwang Phoon  Tsai-Jung Wu 《Georisk: Assessment and Management of Risk for Engineered Systems and Geohazards》2016,10(4):294-311

This paper shows that the transformation uncertainty varies in space and can be decomposed into (a) a slowly fluctuating component contributed by the systematic bias for a local site and (b) a rapidly fluctuating component partly contributed by the measurement error. Based on a piezocone database, the slowly fluctuating component is found to have a vertical scale of fluctuation (SOF) of 17–60 m, larger than the vertical SOFs for most soil properties and characteristic dimensions for many geotechnical structures. This paper provides an empirical basis to justify the assumption that the transformation uncertainty is fully correlated in space.  相似文献