Spectral Analysis of the Earthquake Sources around Roorkee (India) Region and its surrounding Indo-Gangetic Plains

Sen Arup, Kumar Ashwani, Gupta S. C. and Kumar Arjun

The characteristics of earthquake source can be well explained by the estimation of source parameters of that area. A moderate earthquake of magnitude 4.7 occurred on November 6, 1975 around Roorkee region of India. An attempt has been made to understand the seismic pattern and behavior of the earthquakes around Roorkee and its adjacent areas. The source parameters of 65 events have been estimated using the spectral analysis of SH-component of shear waves from the three component digital seismogram applying Brune model which falls in the study area encompassing Garhwal Lesser Himalaya and Indo-Gangetic plains. The values of Seismic moment (M0), Moment magnitude (Mw), Source radii (r) and Stress drops (σ) of sixty five events vary from 1.58 x 1011 (Nm) to 1.99 x 1014 (Nm), 1.4 to 3.3, from 139 m to 397.4 meters and between 0.199 bars to 25.8 bars. The values of stress drop increase significantly towards Indo-Gangetic plain indicating stress buildup. Two different data have been taken for computation of M0 vs. f0 scaling law, as generally breakdowns of self similarity have reported for events with moment magnitude less than 2.5. Another empirical relation Log M0 (N m) = 2.610 ML + 10.301 has been estimated between the seismic moment, M0 and local magnitude ML. This relation can be adopted to estimate Mw from ML in the magnitude range from 0.5 to 4.5. The near surface attenuation factor (κ) is found to be large, of the order of 0.02 suggesting thick low velocity sediment beneath the region.

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Development of Fault and Seismicity Maps for the State of Goa, India

Naik Nisha and Choudhury Deepankar

Earthquake magnitude recurrence relations are developed for the State of Goa on the west coast of Peninsular India. The Seismic influence zone for the study area of Goa was considered as 350 km from the state boundary. The zone comprises mainly of Koyna on the North, Latur region on the North – east and the Karnataka region on the west. The earthquake data consisted of both historical and instrumental earthquakes from the year 1767 to 2013. Foreshocks and aftershocks were removed from the catalogue and the de-clustered catalogue was tested for completeness by Cumulative VIsual (CUVI) method. The spatial and temporal distribution of the earthquake events in the Seismic influence zone of the study area was obtained. The recurrence relation established for the State of Goa was log λm = 6.41 – 0.91Mw. The Fault map and the Seismo-tectonic map of Goa were developed. To ascertain the extent of influence of the past earthquakes in the seismic influence zone on the study region of Goa, intensity based maps were developed for 5 past earthquake events. It was found that a maximum Intensity VII on MSK scale could be felt in the State of Goa in the case of re-occurrence of past earthquake events at or near the same location.

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Landslide Detection from Satellite images using Spectral Indices and Digital Elevation Model

Singh Krishna Kant, Mehrotra Akansha and Pal Kirat

An automatic approach for landslide detection from remote sensing images and digital terrain information is presented in this paper. The method classifies the pre and post landslide images using Normalized Difference Vegetation Index (NDVI), Normalized Difference Building Index (NDBI) and first component of Principal Component Analysis (PCA).The mean value of different classes is estimated using these images. The mean values are used by the minimum distance classifier to classify the images into different classes. Landslides result in loss of vegetation thus the change information is extracted by comparing the pre and post landslide classified images. Finally, slope of the changed areas is computed using Digital Elevation Model (DEM) and those points where slope is greater than a threshold value are validated as landslides. The proposed method is applied on Landsat 5 and Advanced Land Imager (ALI) EO-1 satellite images to detect the landslides that occurred in Sikkim state of India due to the Sikkim 2011 earthquake of magnitude Mw = 6.9. The terrain information is obtained using ASTER Digital Elevation Model (DEM) of the area. The results show that the landslides are detected accurately and efficiently.

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Early-warning approaches for landslide using rainfall indices

Kung Gordon Tung-Chin, Wang Chien-Chih, Tamrakar Surendra Bahadur, Tang Yu-Geng, Hsu Shih-Tsung and Lien-Chieh Chen

Landslides frequently occur during typhoon and Mei-yu seasons in Taiwan. As such, rainfall is the predominant factor causing the landslide disaster and thus it is desirable to develop method for forecasting the occurrence of landslides. This study collected a total of 148 landslide case histories recorded during 2006-2011 and analyzed the rainfall characteristics of these events. Then, two rainfall indices, one is short-term rainfall index in terms of 60-mins rainfall (rainfall intensity) and the other is long-term rainfall index in terms of accumulated precipitation (antecedent precipitation), are employed to develop early-warning approaches for forecasting the landslides. The concept of half-time is incorporated in calculating the contribution of antecedent precipitation prior to the occurrence time of landslide. The analysis results showed that the use of only one index, either the rainfall intensity or the antecedent precipitation, is not feasible for forecasting the occurrence of landslide. However, it revealed that the critical line developed by using two indices, the rainfall intensity and the antecedent precipitation, based on the four cases collected within a county is capable of identifying the boundary for forecasting the occurrence of landslide. Moreover, the difference in the accuracy of the three critical lines developed based on various scenarios of the antecedent precipitation in forecasting the occurrence of landslide is very less. The results of this study may provide a basis for further developing the early-warning approach for landslide forecasting at other areas.

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Computer Simulation of Evacuation and Escape from a Fire in an Entertainment Venue and Analysis of the Effect of Panic Psychology on Evacuees

Cherng-Shing Lin, Te-Chi Chen and Meng-Yin Chen

Entertainment venues are used for relaxation. Because such venues usually have a large number of guests, emphasizing and reinforcing their fire protection and safety is crucial. This study used the fire at the Ala Pub in Taichung City, Taiwan as a case study, applied Fire Dynamics Simulator (FDS) fire simulation software to analyze the fire field, compared and verified the data with pictures and information on the case, reconstructed the fire field by using a numerical model and rebuilt the fire context based on the results. Subsequently, evacuation and escape were simulated to examine the behaviors of the evacuees when evacuating and escaping from the fire field. The results indicate that the complexity of interaction between the rising of panic and scaring influenced their escape behaviors, thus yielding in differing results (i.e. death and survival). Furthermore, the simulation was used to examine the manner in which the fire field influenced the evacuation and escape of the evacuees under various heat release rates. This paper presents related quantified data, simulation results and analysis for improving evacuation and escape from entertainment venues in the event of fires to minimize the effects of fire.

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Single pile responses due to lateral spreading in two- and three-layered slopped ground

Lu Chih-Wei, Lin San-Shyan, Lin Jia-Shin, Kung Gordon Tung-Chin, Chien Chih-Jung and Lee Hsien-Yi

In this paper, the responses of single pile foundation due to liquefaction- induced ground flow in a physical model test were calculated using a 3-dimensional soil-water coupled dynamic analysis. The numerical procedure was used to simulate centrifuge test data from Abdoun et al1 in which seismic responses of a single pile foundation installed in slopping two- and three-layered grounds were carried out. The authors simulated the series of experiment tests numerically not for analysis validation but for a comparative discussion on the capability of the numerical approach to simulate an object in physical test and probe into the failure mechanism of the piles due to the lateral spread liquefied soils. As a result, the numerical simulation revealed general consistency to physical measurements of ground surface movement, pile head movement, and bending moment development in both sloping two- and three layered ground consisted of loose sand I and II respectively. Normalized bending moment distributions and ground displacement distributions in two- and three- layered also showed good agreement. In the normalization, M or H meant the bending moment or displacement of pile at any time, Mmax and Hmax meant maximum bending moment or displacement of pile. Numerical analysis predicted much greater value of displacement and bending moment because of much movable boundary provided in the numerical analysis. It illustrated that in design of liquefaction remediation to measures for single pile project, the results from both of centrifuge experiments and numerical modeling could be the usefulness and applicability in simulating the bending responses of single pile foundation to lateral spreading while the limitation was understood.

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Application of catastrophic theory on stability analysis of the counter-inclined stratified rock slope

Luo Hongming, Chen Shanxiong and Wang Guobin

The stability-losing of the counter-inclined stratified rock slope is one of the most urgent problems in engineering geology and rock mechanics. The catastrophic model with cusp point on the basis of catastrophic theory is established which is based on the rock mass structural characteristic of the counter-inclined stratified rock slope and the geological model and the bulking-tearing deformation. The conditions and mechanism of sudden change of stability-loss are studied as well. The critical stability-loss deepness of an instability point is given by the model. The method of stability evaluation is carried out based on catastrophic theory. A case for Zhangjiazui high cutting slope is studied by stability evaluation based on catastrophic theory. The results showed that the stability coefficient is 1.31 and the method of stability evaluation is effectively successful in the counter-inclined stratified rock slope.

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Study of rock burst quantitative prediction based on improved entropy coefficient and efficacy coefficient method

Xu Jie, Liu Quansheng, Jiang Jingdong and Liu Bin

Rock burst is a common engineering geological disaster in deep rock excavations. Multi-objective programming principle of efficacy coefficient method is suitable for the evaluation of rock burst intensity and quantitative prediction. Based on the efficacy coefficient method, a model for predicting and classifying rock bursts was established. Considering the key affecting factors of rock burst comprehensively, three factors were selected as evaluation indexes including the ratio of maximum tangential stress and rock uniaxial compressive strength, the ratio of compressive and tensile strength of rock and elastic energy index. Improved entropy method was adopted to determine the weighting coefficient of each evaluation index. Finally, the model was applied to predict rock burst in diversion tunnels of Jiangbian hydropower project.

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Social vulnerability and sedentarisation of pastoralists in Gode Zone, Ethiopia

Maputseni Clever and Ncube Alice

The study determined whether nomadic pastoralism increased or was a cause of vulnerability to hazards in Gode Zone (Ethiopia). The effect of sedentarisation on pastoralist livelihoods, whether this reduced vulnerability and could be considered an effective disaster risk reduction measure was also investigated. The research was survey-based and described sedentarisation and disaster risk management. Data were gathered using observation, interviews and document reviews. Overall risk scores suggested that sedentarisation was marginally more advantageous than pastoralism, but the advantage seemed too small to pass sedentarisation as an alternative to pastoralism. From the findings and taking the arid environment into consideration, it was not apparent that pastoralists necessarily needed to be sedentarised in order to reduce their risks. Government support to both may see pastoralism and sedentarisation mutually and successfully co-existing but the current policy for Gode Zone seemed to pursue the gradual end of pastoralism.

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Prolonged sedimentary effect from Earthquake-induced Landslides in Qionghai Lake basin, Southwest of China

Wei Xueli and Chen Ningsheng

Earthquake-triggered landslides are major geological hazards in eastern Tibetan Plateau and have prolonged impact on sediment yield. To determine for how long co-seismic landslides affected sediment yield in a basin, massive number of landslides existing in Qionghai Lake Basin were investigated about landslide distribution characteristics and geomorphological evidences and were further compared and analyzed using historic seismic analog method. These landslides found in Qionghai Lake Basin showed markedly features of seismic triggering strongly controlled by Zemuhe fault. Only one major landslide event occurred during the past 160 year period. Thus, we inferred that abundant landslides in Qionghai Lake Basin originated from 1850 Xichang large earthquake (MS7.5). These landslides are still active at present and some new distributed slides generally occurred in ancient slope failure zones which caused severe sediment deposition in recent years. The 1850 huge earthquake led to large amounts of unstable slopes with comprehensive fissures and cracks, predominating geological structure and slope failure. The shattering of small frequent earthquakes further increased the weathering of bedrock and enhanced the crack propagation and coalescence and rainfall infiltration into the fissures accelerated and re-motivated slope failure. Thus, in our study the landslides triggered by the 1850 Xichang earthquake (MS7.5) have a longer term impact on sediment yield with a period of more than 160 years.

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