Using Remote Sensing Technology to Assess Land - Use Changes after the Northridge Earthquake

Chang Liang 1 and Tang Zhenghong 2*

The 1992 Northridge Earthquake in Los Angeles, California is one of the costliest natural disasters in the U.S. history, causing more than $22 billion (in 2001 dollars) property damage. Using the U. S. Geological Survey Lands at remote sensing images of Los Angeles area before (1989) and after (2001) the earthquake, this paper aims to investigate how the earthquake affected the urban land use changes in Los Angeles area, California. By comparing the supervised classification of remote sensing images at different time, the land use changes in the seismic risk areas of Los Angeles were identified. The results can be useful for governmental agencies such as emergency management and planning departments as well as private business sectors in the high seismic-risk zones.

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Statistical Spatial Modeling of Ground Subsidence Hazard near an Abandoned Underground Coal Mine

Lee Saro 1*, Oh Hyun-Joo 1 and Kim Ki-Dong 2

This study constructs a hazard map for ground subsidence around abandoned underground coal mines (AUCMs) at Samcheok City in Korea using a probability (frequency ratio) model, a statistical (logistic regression) model and a Geographic Information System (GIS). To evaluate the factors related to ground subsidence, an image database was constructed from a topographical map, geological map, mining tunnel map, global positioning system (GPS) data, land use map, digital elevation model (DEM) data and borehole data. An attribute database was also constructed from field investigations and reports on the existing ground subsidence areas at the study site. Seven major factors causing ground subsidence were extracted from the probability analysis of the existing ground subsidence area: 1) depth of drift from the mining tunnel map and distance from drift; 2) slope gradient, calculated from the topographical map; 3) groundwater level and permeability, from borehole data; 4) geology from the geological map; and 5) land use from the land use map. The frequency ratio and logistic regression models were applied to determine each factor’s rating and the ratings were overlain for ground subsidence hazard mapping. The ground subsidence hazard map was then verified and compared with existing subsidence areas. The verification results showed that the logistic regression model (accuracy of 96.75%) is better in prediction than the frequency ratio model (accuracy of 95.64%). The verification results showed sufficient agreement between the hazard map and the existing data on ground subsidence area. Analysis of ground subsidence with the frequency ratio and logistic regression models suggests that quantitative analysis of ground subsidence near AUCMs is possible.

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Performance based Architectural Design Guideline for Multi-Storied Buildings in Seismic Zones

Bhattacharya S. P.1* and Chakraborty S. K.2

In the present article a four storey reinforced framed building structure with regular symmetrical plan is modeled for the seismic simulation. The analysis is encountered under the bureaus of Indian Standard provisions. Here, the building is considered to be situated at earthquake zone-V on a site with medium soil. Response spectrum method based on modal combination is adopted for the mathematical modeling of the structure. The mass and stiffness of the various floors of the building are being interacted in the model. The variability of the mass and stiffness in the top floor, intermediate floors and ground floor provides forty nine different cases for the entire study. The investigation finally reveals the significant /insignificant modal condition in comparison to the betterment of the design criteria in respect to architectural scenario.

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Cold Sea Outbreak near Cheju Island under Strong Wind and Atmospheric Pressure Change by Typhoon Rusa

Choi Hyo*

Cold sea water outbreak after the passage of Typhoon Rusa across Cheju Island in the south sea of Korea was investigated using GMS-MCSST satellite image of sea surface temperature (SST) distribution and GMS-Infrared image of cloud and a three dimensional non-hydrostatic numerical model - Weather Research & Forecasting Model (WRF) version 2.2 with FNL initial meteorological data from 0000 UTC, August 30 through 12 UTC, September 1, 2002. Before typhoon on August 29, northeasterly sea surface winds in the vicinity of Cheju Island were moderately less than 5 m/s and SST was 290C. After the typhoon passed across the island after 1500 LST on August 31, cyclonic surface winds were more than 12 m/s and the SST in the coastal sea of the island was remarkably changed into 170C, showing a 120C decrease. A cyclonic wind of typhoon and a fast movement of typhoon caused a divergence of ocean current by upwelling (Ekman pumping) process by which deep sea cold water was brought to the sea surface and outward spreading of cold water, resulting in colder water outbreak near the island, especially its observation behind the typhoon on its track. Simultaneously, on the typhoon track, negative minimum geo potential tendency of 500 hPa for 24 hours, was detected in typhoon eye and its vicinity where the shrunken of atmosphere existed in the negative area. On the other hand, a positive maximum value of geo potential tendency of 256 m/day was detected behind the moving typhoon, where the atmospheric depth should be maximum expanded and the expansion of the atmosphere induces ascending of sea surface, resulting in upwelling of deep sea cold water into the sea surface and extreme low temperature distribution in the southwestern coastal sea of Cheju Island.

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Simulation of Snow Drifting on Roof Surface of Terminal Building of an Airport

Zhou Xuanyi* and Li Xuefeng

For large-span roofs of unusual geometry, the effects of snow drifting on roof snow loads deserve more detailed study. Drifting snow in wind is considered in this paper as a two-phase flow problem. The mixture of air and snow is assumed to be one-way coupled so that the air phase can be treated as unaffected by the airborne snow and the snow transport is mainly controlled by the air flow and surface conditions. The commercial CFD software, FLUENT, is adopted with additional user C++ code. The mean wind pressures on the terminal 3A of Beijing International Airport obtained from the wind tunnel test and numerical method are first compared to verify the reliability of the CFD results to some extent. Then the characteristics of snow distribution on the building roof are numerically simulated. Finally the effects of some major parameters including the type of turbulence model, threshold of friction velocity, magnitude of wind velocity and wind directions, on the snow drift are analyzed.

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Disasters and Risk Reduction in Groundwater: Zagros Mountain Southwest Iran Using Geoinformatics Techniques

Ayazi M. Hasan 1, Pirasteh Saied* 1, 2, Pili A. K. Arvin 2, Pradhan Biswajeet3, Bijan Nikouravan4 and Shattri Mansor2

For more effective use of ground fresh water resources, a remote sensing and GIS have been used in many places in last decades. The digital topographic maps in scale 1:25000 within GIS environment have been studied to observe the risk reduction and changing of the water resources because of the tectonic activities which are crucial to generate a groundwater disaster in the study area. The area has been visually and digitally interpreted to delineate DEM, drainage network, drainage basin, karst landforms, lineaments and lithology for ground water reduction and possible new locations to explore and reduce the risk reduction and disasters. Image elements are used during visual and digital interpretation. Extensive field works have been attempted using global positioning system (GPS) to collect water samples. The study shows that the groundwater is controlled by geomorphology, landslides, lineament analysis, lithology and topography in the study area. This study shows the advantages of remote sensing and GIS techniques for Karst and water resources study. Use of GIS-technologies makes it possible to construct 3D models of river basins and adjust theoretical reserves of the deposits.

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Assessment of population doses and radiation hazards from rock samples collected in the South West of Cameroon

Abiama Ele P1, 3., Owono Ateba P 3., Ekobena F. H. P 3., Ben-Bolie G. H*3. and El Khoukhi T 2.

The concentrations of the natural radionuclides: 226Ra, 232Th, 40K, have been determined in syenites which are typical rocks from Awanda, Bikouéssi, and Ngombas, localities in the South West of Cameroon. A HPGe p-type detector coupled to a multichannel analyzer was used to perform measurements and data processing. The highest average value of 226Ra concentration (4026±270 Bq/kg) was observed at Ngombas whereas the highest average value of 232Th concentration (1385±176 Bq/kg), were detected at Awanda. However 40K contributes significantly to increase the radioactivity in rocks from the three locations studied in this work. The radium equivalent activity Raeq, the external hazard index Hex, the outdoor absorbed dose rate D in air and the annual effective dose equivalent E were evaluated to external radiation exposure for people living to studied areas. The mean absorbed dose rate in air is 1427.49 n Gy/h at 1.0 m above the soil.

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