Isoseismals for the Kutch earthquake of 26th January 2001 (original) (raw)
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Bulletin of Earthquake Engineering, 2011
Although the M w = 6.1 Kovancilar-Turkey earthquake of March 8, 2010 had a moderate intensity with a recorded PGA of 0.07g, it caused heavy damages in 2870 residential buildings having traditional or masonry structural systems and 42 human loss. Damage has been reported to be particularly concentrated at Kovancilar and Palu counties of Elazig province. Five hours after this earthquake, an aftershock of M L = 5.6 with a PGA of 0.08g struck the same region, developing the existing damages in the structures. In order to investigate this significant amount of reported damages under the effect of such low ground shakings, our reconnaissance team arrived at the region and unexpectedly came across a two-story RC building settled on a slope in Yukari Demirci village, which suffered moderate damage during the shakes. The outline of this paper can be summarized as the presentation of the results of the investigations in the order of describing the overall observed damages within the region; evaluation of the recorded motions; the details of the field-work carried out for the two story RC building and the analytical estimation of the site-assessed damages by means of nonlinear dynamic analysis. Employing the gathered data, the building is analytically modeled as plane frames and analyses are performed under the effects of the processed earthquake records, which are applied to the structure one after another in the consistent directions due to the building location. It is shown herein that the structural elements remain in the elastic range subjected to the processed recorded motions; henceforth acceleration time histories are scaled step by step up to 0.40g and computations are repeated for each acceleration level. Comparison with the observed and the analytically obtained damages confirmed that approximately 0.30g of peak ground acceleration should have to be exposed during the earthquakes.
Aftershocks of 26th january 2001 Bhuj earthquake and seismotectonics of the Kutch region
Journal of Earth System Science, 2003
The 26th January 2001 Bhuj earthquake was followed by intense aftershock activity. Aftershock data from United States Geological Survey (USGS) utilized in this study encompasses three months period from 26th January to 26th April 2001. Epicenters of the aftershock are plotted on a map depicting active faults. All the aftershocks of magnitude > 5 and 70% of those ranging between magnitude 3 and 5 are confined to an area resembling a horseshoe pattern with a pointed end towards NE. The other 20% of magnitude 3 to 5 are enclosed within an almost parallel boundary. Only 10% are found to be beyond this limiting boundary. 50% of the recorded aftershocks took place within the first week of the main event and this study reveals that the basic characteristic pattern of aftershock activity can be determined on the basis of the data of only one week. Four major NW-SE trending active faults are mapped in the Kutch region. They define the western limit of Cambay structure and also mark the western limit of Dharangadhra and Wadhwan basins along the SE continuation in Saurashtra. These faults separate the Kutch region into two geologically different blocks. On the SW side the mapped horseshoe pattern gets characteristically truncated along the western most fault, which is characterized by a strike-slip movement in the south and vertical movement in the north. The present study has revealed that the epicenter of the 26th January earthquake is located in the vicinity of the Bhachau township, close to the intersection with the Kutch mainland fault. Furthermore, it has been noticed that most of the epicenters of the aftershock are confined in the intersectional area of the Kutch mainland fault and the NW-SE faults.
Intensity distribution of M 4.9 Haryana–Delhi border earthquake
Natural Hazards, 2013
In this study, we have prepared an intensity map based on macroseismic survey and all the available information from print and electronic media of damage and other effects due to March 05, 2012, M 4.9 Bahadurgarh (Haryana-Delhi border) earthquake and interpreted them to obtain modified Mercalli intensities (MMI) at over 62 locations surrounding the Haryana and Delhi. We have cross-checked the damage information from print and electronic media in the field at 25 sites within 110 km surrounding the epicenter for validation. Based on the questionnaire which is used in macroseismic survey and personal judgment, intensities were assigned accordingly as per physical survey at 25 sites and for rest based on media reporting. A maximum intensity of VI was assigned to this seismic event. Isoseismals of V and VI have been fully covered in the field observations. Beside this, some of the points have also been covered for isoseismal IV and isoseismal III and rest are based on media report only. The intensity map reveals several interesting features. Elliptically elongated shape of intensity map shows that most of the slightly damaged areas are concentrated toward the northwestern side of the epicenter having intensity V which may be due to directivity or site effects. A regression relation has also been derived between intensity and epicentral distance. The derived attenuation relation will be useful for assessing damage of a potential future earthquake (earthquake scenariobased planning purposes) for the Delhi NCR region.
Earthquake Spectra, 2007
Seismic intensity in the epicentral area of the 2003 Bam, Iran earthquake is estimated using a questionnaire survey conducted two months after the earthquake. The estimated average seismic intensity on the Japan Meteorological Agency (JMA) scale is 6.1 (VIII to IX in the MMI scale). The peak frequency of the horizontal-to-vertical spectral ratio derived from microtremor measurements conducted during reconnaissance is also compared with the seismic intensity. Collapse rates for various structure types, such as adobe, unreinforced/reinforced masonry, steel-frame, and reinforced concrete, are obtained by counting the number of demolished buildings within an area of about 50-m radius around an observation point. Results show large differences in collapse rates between unreinforced and reinforced masonry, and suggest the upper limit of seismic intensity that unreinforced masonry can sustain. This fact can be utilized for an initial damage assessment within affected areas after large earthquakes.
Earthquake Spectra, 2006
Reconnaissance surveys of building and infrastructure damage related to geotechnical engineering aspects were conducted four to six weeks after the 26 December 2004 earthquake and five weeks after the 28 March 2005 earthquake. These surveys identified many instances of building collapse and infrastructure damage that were probably caused by strong ground shaking and/or liquefaction-induced foundation or embankment failures. The survey results suggest the need for earthquake engineering research that identifies likely future earthquakes and their ground motion characteristics. Because of the observed variation in the level of damage, a seismic microzonation study should be performed to identify the spatial variability of strong ground shaking for the purpose of reconstruction and future planning of cities in Nangroe Aceh Darrusalam Province and Nias Island.
ASSESSMENT OF POST EARTHQUAKE DAMAGE AT BAGH DISTRICT, AJK THROUGH GEOSPATIAL TECHNOLOGIES
Earthquake is most unpredictable natural hazard, which creates sudden change in the normality of social processes. More than a million earthquakes arise around the world every year at the rate of two earthquakes per minute. Catastrophes have caused more than 780,000 deaths during the period of 2001-2011 of these calamities, the death toll caused by the earthquakes was estimated nearly 60% due to non-engineered building design and poor construction materials. Kashmir is highly vulnerable to seismicity because of consistent collision of Indian and Eurasian plates, while former continue to move into latter, thus building up great pressure at faults. This region was struck by severe earthquakes and hit a huge magnitude, consequently excessive loss was observed in the past 1555 and 1885. Recently in 8th October 2005 most disastrous earthquakes jolt the Azad Kashmir with the magnitude 7.6. Therefore, the objective of current study is to evaluate the postearthquake damage through Satellite Remote Sensing (SRS) mainly through visual interpretation techniques. In addition, to analyze the main effect of earthquake on human settlements and to evaluate the infrastructure and buildings damaged by the earthquake. GPS coordinated field survey has been conducted and marked the affected houses on Landsat-7 image by using geospatial techniques with the help of ArcGIS and ERDAS imagine software. The results show the identification of four different types of building (walls was made-up of mud, blocks, stones and bricks, while the roof comprised of iron sheet, wooden roof, reinforced concrete (RC) respectively) on the basis of the construction material used in the District Bagh. Preparedness of earthquake can effectively reduce the economic losses and fatalities that caused by earthquakes. This study focused on the preparedness of the peoples of mountainous areas (District Bagh is earthquake prone area) that which building material is suitable for the construction and the ultimate resilience. The proportion of engineered building was relatively low and approximately 90 % buildings were found non-engineered design in District Bagh.
Experimental vulnerability curves for the residential buildings of Iran
Natural Hazards, 2012
Iran is one of the most seismically active countries of the world located on the Alpine-Himalayan earthquake belt. More than 180,000 people were killed due to earthquakes in Iran during the last five decades. Considering the fact that most Iranians live in masonry and non-engineered houses, having a comprehensive program for decreasing the vulnerability of society holds considerable importance. For this reason, loss estimation should be done before an earthquake strikes to prepare proper information for designing and selection of emergency plans and the retrofitting strategies prior to occurrence of earthquake. The loss estimation process consists of two principal steps of hazard analysis and vulnerability assessment. After identifying the earthquake hazard, the first step is to evaluate the vulnerability of residential buildings and lifelines and also the social and economic impacts of the earthquake scenarios. Among these, residential buildings have specific importance, because their destruction will disturb the daily life and result in casualties. Consequently, the vulnerability assessment of the buildings in Iran is important to identify the weak points in the built environment structure. The aim of this research is to prepare vulnerability curves for the residential buildings of Iran to provide a proper base for estimating probable damage features by future earthquakes. The estimation may contribute fundamentally for better seismic performance of Iranian societies. After a brief review of the vulnerability assessment methods in Iran and other countries, through the use of the European Macroseismic method, a model for evaluating the vulnerability of the Iranian buildings is proposed. This method allows the vulnerability assessment for numerous sets of buildings by defining the vulnerability curves for each building type based on the damage observations of previous earthquakes. For defining the vulnerability curves, a building typology classification is presented in this article, which is representative of Iranian building characteristics. The hazard is described in terms of the macroseismic intensity and the EMS-98 damage grades have been considered for classifying the physical
Damage Analysis of the Great East Japan Earthquake
This paper tries to comprehensively summarize the reasons of damages at the Great East Japan Earthquake on March 11, 2011 and what are the lessons in terms of earthquake and tsunami safety of building and cities. The paper examines the damage of tsunami affected areas and analyses the damage to extract lessons in order to safely reconstruct the affected areas from the view point of building regulations such as " Disaster Risk Area " provided by the Article 39 of the Building Standard Law and the Urbanization Control Area and UPA (Urbanization Promotion Area) provided by the Article 8 of the Ordinance of the City Planning Law of Japan.