Abstract

The great devastating tsunamigenic earthquake of 26 December 2004 in sumatra was quickly followed by another great one on 28 march 2005 in the same region. This is for the first time in the known histroy of seismology that 2 great earthquakes have occurred in close spatial proximity in such a quick succession. In the present study we highlight the role of the multiple plate junction comprising the India, Burma, Australia and Sunda plates in in generation of such great earthquakes.

Abstract

This article aims to understand the response of soil deposits underlying bedrock fault displacement in three dimensions. When an active bedrock fault ruptures, movement along the fault propagates through the overlying soil and produces zones of intense shear. Hence, it is important to study the surface behaviour based on fault characteristics. Hence we attempted to develop application of Ap- plied Element Method by modelling the fault rupture zone. In this article, we have modelled the fault rupture problem in three dimensions. First, a simple model is used to illustrate absorption of the bedrock deformation by the overlying soil in elastic case. In the later part, nonlinear analysis is car- ried out to study the complex failure propagation in three dimensions. Influence of mechanical properties of the material is also discussed.

Abstract

The great devastating tsunamigenic earthquake of 26 December 2004 (M9.0) in Sumatra was quickly followed by another great one on 28 March 2005 (M8.7) in the same region. This is for the first time in the known history of Seismology that 2 great earthquakes have occurred in close spatial proximity in such a quick succession. In the present study we highlight the role of the multiple plate junction comprising the India, Burma, Australia and Sunda plates, in generation of such great earthquakes. The 26 December 2004 and the 28 March 2005 earthquakes in the Andaman-Sumatra arc seem to have occurred on distinct India-Burma and Australia-Sunda mega-thrust segments possibly separated by a stress barrier or a lithospheric break at the junction that prevented stress transfer along the arc during both earthquakes. This is evidenced by the confinement of aftershock activity on either sides of the barrier during each of the earthquakes. It appears that the large impulsive co-seismic deformation during the first earthquake of 26 December 2004 triggered the already saturated adjoining segment of the Australia-Sunda plate boundary within a short period of 3 months, generating the second one on 28 March 2005. An examination of the locations of the world’s 12 largest earthquakes since the year 1900 indicates a strong correlation (>80%) with multiple plate junctions. Apart from the 2 great Sumatran earthquakes observed at the quadruple plate junction of India, Burma, Australia and Sunda, even the 2 greatest earthquakes in the Himalayas – the 1897 Shillong and the 1950 Assam earthquakes – each of magnitude 8.7, occurred at a quadruple junction near the eastern Himalayan syntaxis, comprising the India, Eurasia, Burma and Sunda plates. Finite element modeling of stress field at plate junctions indicates the mechanism of great stress build-up due to the plate geometry and variable plate velocities. In general, it is inferred that triple and quadruple plate junctions are potential targets for future great earthquakes.

Abstract

The great devastating tsunamigenic earthquake of 26 December 2004 (M9.0) in Sumatra was quickly followed by another great one on 28 March 2005 (M8.7) in the same region. This is for the first time in the known history of Seismology that 2 great earthquakes have occurred in close spatial proximity in such a quick succession. In the present study we highlight the role of the multiple plate junction comprising the India, Burma, Australia and Sunda plates, in generation of such great earthquakes. The 26 December 2004 and the 28 March 2005 earthquakes in the Andaman-Sumatra arc seem to have occurred on distinct India-Burma and Australia-Sunda mega-thrust segments possibly separated by a stress barrier or a lithospheric break at the junction that prevented stress transfer along the arc during both earthquakes. This is evidenced by the confinement of aftershock activity on either sides of the barrier during each of the earthquakes. It appears that the large impulsive co-seismic deformation during the first earthquake of 26 December 2004 triggered the already saturated adjoining segment of the Australia-Sunda plate boundary within a short period of 3 months, generating the second one on 28 March 2005. An examination of the locations of the world’s 12 largest earthquakes since the year 1900 indicates a strong correlation (>80%) w

Abstract

India has witnessed 6 earthquakes during past 15 years causing around 40,000 casualties and immense property loss. More than 90% of these casualties are due to collapse of buildings and they occurred within very short period of time after the earthquake. Hence, for reducing casualty losses and subsequent consequences due to earthquake, it is very important to study the response of structures due to seismic excitations. For studying the response of the structures and consequent issues after the earthquake disaster, information technology can play a major role. This paper contributes to understand the importance of information technology in earthquake disaster mitigation

Abstract

Earthquake, now everyone is familiar with this word. We have clearly witnessed during the recent Sumatra, Indonesia earthquake (M 9.0) the amount of damage an earthquake can cause to the society. Had this earthquake occurred on land, it would have easily damaged few hundreds of kilometers and the damage estimates would have been unimaginable. Earthquakes are not new to our country. We have had the long history of earthquake occurrences. Some of the major earthquakes of the world occurred in our country and neighborhood areas. During past 15 years also we have witnessed 6 moderate earthquakes: Bihar-Nepal border (M6.4) in 1988, Uttarkashi, Uttaranchal (M6.6) in 1991, Latur, Maharastra (M6.3) in 1993, Jabalpur, Madhya Pradesh (M6.0) in 1997, Chamoli, Uttaranchal (M6.8) in 1999 and Bhuj, Gujarat (M6.9) in 20011). These earthquakes caused around 40,000 casualties (see Table 1) and innumerable property loss. These events occurred with a time gap of 2 ~ 3 years. Are we ready to face another event?

Abstract

Natural disasters like earthquake, landslide, flood, drought, cyclone, forest fire, volcanic eruption are quite common in different parts of the globe. These natural disasters lead to the loss of life, property damage and socio-economic disruption. Earthquakes are one of the worst among the natural disasters. Seismic zonation map given in IS 1893:2002 shows that India is highly vulnerable for earthquake and over 60% of India is prone to moderate to major earthquakes. During past century, India has witnessed more than 650 earthquakes of magnitude greater than 5 and during past 15 years, 6 earthquakes of magnitude over 6. From recent earthquakes, it is very well understood that lack of awareness is one of the contributing factors for huge casualty losses. In order to increase the awareness about the effects of earthquakes among professionals involved in construction, it is necessary to make them understand the concepts of structural dynamics and earthquake engineering. For this, we have developed a software tool called “Interactive Structural Dynamics Learning Kit (ISDLK)” for explaining structural dynamics in a simple manner. For convenience in explaining the concepts, we divided the tool into six modules. Each module contains few experiments with good G.U.I. In these modules, user can input the value and he/she can find the desired results with explanation using graphical diagram. At the end of sixth module, user can understand the complete dynamic behavior of a structure. ISDLK aims to help students, architects and design professional in understanding structural dynamics.

Abstract

Earthquake problems in India need no introduction. From recent earthquakes, it is very well understood that lack of awareness is one of the contributing factors for huge casualty losses. In order to increase the awareness about the effects of earthquakes among professionals involved in construction, it is necessary to make them understand the concepts of structural dynamics and earthquake engineering. To address this issue, we have developed a software tool named Virtual Structural Dynamics Laboratory. Using this tool, a person with some knowledge of structural engineering can be able to learn by himself the fundamentals of structural dynamics. For convenience in explaining the concepts, we divided this tool into four modules. Each module contains few experiments with good G.U.I. In these experiments, user can find the explanation with graphical diagram. At the end of fourth module user can understand the dynamic behavior of the structure. This software tool aims to help students, architects and civil engineers in understanding the principles of structural dynamics.

Abstract

When an active bedrock fault ruptures, the movement along the fault propagates through the overlying soil and produces zones of intense shear. If the fault movement propagates upto or near the ground surface, the damage to constructed facilities due to faulting, in conjunction with that induced by strong ground motion, can be significant. This paper contributes to the understanding of the response of soil deposits to the underlying bedrock fault displacement. In the conventional attenuation relationship, peak ground acceleration shows maximum value at the closest distance from the fault. However, in the real observations, sometimes it is found that the damage near to the surface fault is not maximum, instead it is high little away from the surface rupture zone. To understand the above-mentioned response of soil deposits, we attempted to develop a new application to Applied Element Method (AEM) by modeling the fault rupture zone. In this, we study the behavior of dip-slip faults. The effect of the slip velocity on the ground motion is studied first and then the attenuation of PGA in the near fault zone is studied. Effect of the material properties is also discussed.

Abstract

This paper presents a software tool for performing the static and dynamic analysis of regular and simple multi-storied structures. This analysis procedure is based on IS 1893:2002 (Part I), Criteria for Earthquake Resistant Design of Structures. This tool is a windows based software program developed in Visual Basic. The tool provides a userfriendly GUI for the calculation of base shear and its distribution over the height of the structure, depending on the input parameters. Usual input parameters are structural dimensions, type of structure, soil type, purpose of structure and location. Though this tool is simple, can be used for verification of design within short time. This tool is aimed to help students, architects and engineers during design of earthquake resistant structures.