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Disaster Advances

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Disaster Advances





Tsunami Hazard Valuation using Spatial Tools for Kuala Muda, Kedah, Malaysia

Seen Mohd. Ibrahim, Zanariah Wan Nor, Shariff Abdul Rashid Mohammed and Fook Loh Kok

Remote sensing technology has great potential for analyzing damages attributed to tsunami impacts in coastal areas. The Indonesian tsunami, triggered by a massive undersea earthquake registering 9.0 on the Richter scale on December 26, 2004, was regarded as the worst case scenario since the Great Chilean Tsunami in 1960. This Indonesian tsunami had caused extensive damages to many countries in Asia including Malaysia. In this study, Kuala Muda, Kedah, Malaysia was selected as the study site to conduct valuation of tsunami affected areas using spatial tools. It has adopted three change detection techniques - image difference, image ratio and pre-post classification comparison to map out tsunami affected areas using SPOT-5 data sets acquired over two dates, one before and the other after the December 26, 2004 tsunami. However only the classification output change map was used for valuation of tsunami affected areas because it has higher accuracy. Contextual information - Digital Elevation Model (DEM) and texture were incorporated in the digital classification of the SPOT-5 datasets. The classification changes showed clearly the tsunami affected coastal features. A digitized cadastral lot map was superimposed on this change map and the damage valuation analysis, based on a model developed in this study, was then done on a lot by lot basis. Valuation was based solely on market land value determined by the valuation agency of Malaysia. Relevant damage statistics of this analysis were tabulated and plotted to show the extent and severity of damage of the individual land lots. This research has proven that SPOT-5, a moderate resolution sensor, was reliable in assessing tsunami damage valuation of the affected study area. Although the information generated was solely based on the market land value of individual cadastral lots, it nevertheless gave a generalized assessment for the purpose of computing compensation to be paid by the Government of Malaysia to the affected land owners.

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A method for Rapid Evaluation of Masonary Buildings against Earthquakes

Alam Mahtab, Mahmoodzadeh Amir and Pirasteh Saied

At the present time weak buildings exist in Esfahan city, Iran which is not able to withstand earthquakes. At the same time, both private and public developers are trying to use scientific methods to prioritize and allocate budget in order to reinforce the weak structures. This is because of the limited financial resources and time. In the recent years the procedure of seismic assessment before rehabilitation of vulnerable buildings has been implemented in many countries. Now, it seems logical to reinforce the existing procedures with the mass of available data about the effects caused by earthquakes on buildings. The main idea is driven from FMEA (Failure Mode and Effect Analysis) in quality management where the main procedure is to recognize the failure, the causes and the priority of each cause and failure. Specifying the causes and effects which lead to a certain shortcoming in structural behavior during earthquakes, an inventory is developed and each building is rated through a yes-or-no procedure. In this way, the rating of the structure is based on some standard forms along relative weights that are developed in this study. The resulting criteria by rapid assessment have indicated whether the structure is to be demolished, has a high, medium or low vulnerability or is invulnerable.

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Landslides and Active Faults Using Remote Sensing and GIS Techniques in Central Alborz Mountains, Iran

Mousavi S. R., Pirasteh S., Shattri M. and Amani A.

The attempt has been done on study of habitat factors for the distribution of 370 landsides. This study is based on landform features and landslides associated with active faults distribution using remote sensing, GIS and GPS techniques in the Central Alborz, North Iran. Field observations show that the mass movements on low angle occur most frequently near to active faults. In steep slopes avalanche and planar slides are dominant. In this study digital image processing has been done on the ASTER L1A, L1B and Landsat7 ETM+ images. GIS layers have been extracted from 370 historical landslides and active faults over the study area. Digital Elevation Model (DEM) (15m) has been generated from ASTER stereo pair data using PCI Geomatica 9.1 software. The use of a (15m) DEM is a potential substitute in tectonic activity analysis, as it highly correlates with slope instability, geomorphologic processes and factors affecting landslides. Appropriate landform parameters have been derived which are indicating landslides and faults distribution, exposure towards rain and snow. Tectonic classification schemes decomposing the landscape into basic landform-elements proved useful for characterizing a zonal, altitudinal landslide classes. The results show that more than 72 percent of landslide points are situated on the active faults buffer zone. It can be used as fundamental data for hazard prediction, land use planning and construction in study area.

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Maximum Entropy Processing of Seismic Waveform Segments: A Novel Approach to Spectral Estimation

Arora S.K.

In the time series processing and analysis of seismic waveform data, the conventional method of spectrum estimation using Fourier transform often limits, at times severely, the spectral resolution so that the vital spectral features characterizing the seismic event not only suffer distortion but also give rise to some artifacts that mislead interpretations in respect of the seismic source. In comparison with this, it has been shown that the concept of maximum entropy (ME) affords efficient determination of spectra practically free from all those drawbacks. In this sense, the ME spectrum is rated far superior to that obtained through the conventional approach. This has been demonstrated by applying the ME technique in two typical cases, one of a synthetic piece of data and the other of a recorded segment of real seismic data. Both the theoretical and practical (computational) aspects of the MEM are dealt in this paper with emphasis on time series analysis and processing of seismic records including beamforming in frequency domain for a linear seismic array of equi-spaced detectors.

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Developing NGO Competencies in Post-Disaster Reconstruction: A Theoretical Framework

Von Meding J. K., Oyedele L. and Cleland D. J.

In the aftermath of recent natural disasters, NGOs have become increasingly involved in the permanent reconstruction of affected communities. These organizations, often operating well outside their expertise, encounter significant barriers as they implement reconstruction programmes. This paper presents the theoretical bedrock of a current research project, the overall goal of which is to design a competency-based framework model that can be used by NGOs in post-disaster reconstruction projects. Drawing on established theories of management, a unique perspective has been developed from which a competency-based reconstruction theory emerges. This theoretical framework brings together three distinct fields; Disaster Management, Strategic Management and Project Management, each vital to the success of the model. This theoretical study will incorporate a critical review of literature within each field. It is imperative that NGOs involved in post-disaster reconstruction familiarize themselves with concepts and strategies. It is hoped that the competence-based frame-work model that is produced on the basis of this theory will help define the standard of best practice to which future NGO projects might align themselves.

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Geophysical investigation of some prominent gully erosion sites in Calabar, southeastern Nigeria and its implications to hazard prevention

Akpan A. E., George N.J. and George A.M.

Prominent gully erosion sites in Calabar have been investigated using Schlumberger’s vertical electrical soundings and 2D imaging technique. These studies were aimed at investigating the remote cause of some isolated gully erosion problems in some parts of the town and to suggest possible remedial measures. Ten vertical electrical soundings involving Schlum-berger electrode array and 2D imaging techniques using Wenner electrode configuration were executed directly at the some gully erosion sites while fifteen vertical electrical soundings were executed outside the erosion devastated areas. Equipment used was a SAS 1000 model of an ABEM terrameter. Both manual and computer modelling techniques were employed to analyse the field data. Results of the analyses show that the subsurface which are nearly uniform in horizontal extent and lithologic composition can be approximated by a 3-4 layered subsurface structure with moderate to high resistivity values. The mean electrical resistivity of the first geoelectric layer is 711 Ωm with an approximate thickness of about 5m. This geoelectric layer was interpreted to be a lateritic sand layer. The second geoelectric layer that was interpreted to be a medium-coarse sand layer has a mean layer resistivity of 1980 Ωm with a mean depth to bottom of about 40m. The third geoelectric layer has a mean layer resistivity of 250 Ωm with a mean depth to bottom of about 55m though this depth could not be determined from the field data at some locations. This geoelectric layer was interpreted to be either a silty, or clayey or very fine sand layer. The fourth geoelectric layer whose thickness could not be determined from the data acquired in the field has a mean electrical resistivity of 2750 Ωm and was interpreted to be another medium-coarse sand layer. These results show that the subsurface is dominated by clastics that are not very susceptible to erosion problem. Thus the erosion problem is suspected to be associated with the energy of the moving water in the water channels that terminates abruptly at some points. Expanding and extending the existing water channels to the natural drains (streams, rivers, etc) that surround the city seem to be a potent remedial measure that can be used to avert the problem. Comprehensive policy on flood plain management and other land use restrictions can help in reducing the problem. Thus, adequate planning and legislation, construction and maintenance are relevant tools that can be employed to check such natural hazards.

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Neural Networks Models for the Flood Forecasting and Disaster Prevention System in the Small Catchment

Sungwon Kim, Jung-Hun Kim and Ki-Bum Park

Neural networks models are applied for the hydrological flood forecasting and disaster prevention system in small catchment, South Korea. Two kinds of neural networks models such as the multilayer perceptron neural networks model (MLP-NNM) and the cascade correlation neural networks model (CCNNM) are used in this study. The optimal parameters are set up during the training performance of the neural networks models. We apply them to evaluate the testing performance of the neural networks models. Neural networks models are used to forecast the flood streamflow at the Musung station (No.1) of the Wi-stream catchment, which was one of the IHP (International Hydrological Program) representative small catchments in South Korea. Cascade correlation neural networks model shows the better statistical results than those of the multilayer perceptron neural networks model. Using the results, we can construct / develop the flood forecasting and disaster prevention system, which include the structure and data-information aspects in small catchment. Further-more, neural networks models generally spend less time for the training performance and can be easily used by the hydrologists and engineers with little background knowledge of the neural networks theory.

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