A STUDY ON EARTHQUAKE HAZARD ASSESSMENT IN PENINSULAR INDIA (original) (raw)
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Earthquake Hazard Assessment of Peninsular India
This paper presents the detailed seismic hazard assessment of the peninsular India (lat. 8°-28°N and long. 67.5°-90°E) which is considered to be seismically most stable landmasses of the Indian plate. Past seismic history in this region (Koyna, etc) clearly shows that the seismicity of the area is varying. There were more than five damaging earthquakes with magnitudes greater than M w 6.0 have occurred in this region, stressing the importance of detailed seismic hazard assessment for the region. For India, published a probabilistic seismic hazard map based on several well identified and prominent source zones in the country. An attempt has been made in this paper to study the present seismic status of this region incorporating the seismicity, tectonic and geological characteristics and using the collected earthquake data Peak Ground Acceleration was estimated using the attenuation relation developed by Iyengar and Raghukanth (2004). Estimated PGA values were used to compute the deviation with respect to assigned PGA values for various regions provided in Indian Standard code IS 1893:2002. The results show that, the estimated PGA in many areas of the Peninsular India is more than the specified value in the current seismic macrozonation map of the country. This provides an important basis for attempting the detailed microzonation of an area within the Penisular India.
Spatial-temporal variability of seismic hazard in peninsular India
Journal of Earth System Science, 2008
This paper examines the variability of seismic activity observed in the case of different geological zones of peninsular India (10 • N-26 • N; 68 • E-90 • E) based on earthquake catalog between the period 1842 and 2002 and estimates earthquake hazard for the region. With compilation of earthquake catalog in terms of moment magnitude and establishing broad completeness criteria, we derive the seismicity parameters for each geologic zone of peninsular India using maximum likelihood procedure. The estimated parameters provide the basis for understanding the historical seismicity associated with different geological zones of peninsular India and also provide important inputs for future seismic hazard estimation studies in the region. Based on present investigation, it is clear that earthquake recurrence activity in various geologic zones of peninsular India is distinct and varies considerably between its cratonic and rifting zones. The study identifies the likely hazards due to the possibility of moderate to large earthquakes in peninsular India and also presents the influence of spatial rate variation in the seismic activity of this region. This paper presents the influence of source zone characterization and recurrence rate variation pattern on the maximum earthquake magnitude estimation. The results presented in the paper provide a useful basis for probabilistic seismic hazard studies and microzonation studies in peninsular India.
Probabilistic Assessment of Earthquake Hazard in Gujarat and Adjoining Region of India
Pure and Applied Geophysics, 2008
The maximum likelihood estimation method is applied to study the geographical distribution of earthquake hazard parameters and seismicity in 28 seismogenic source zones of NW Himalaya and the adjoining regions. For this purpose, we have prepared a reliable, homogeneous and complete earthquake catalogue during the period 1500-2010. The technique used here allows the data to contain either historical or instrumental era or even a combination of the both. In this study, the earthquake hazard parameters, which include maximum regional magnitude (M max ), mean seismic activity rate (k), the parameter b (or b = b/log e) of Gutenberg-Richter (G-R) frequency-magnitude relationship, the return periods of earthquakes with a certain threshold magnitude along with their probabilities of occurrences have been calculated using only instrumental earthquake data during the period 1900-2010. The uncertainties in magnitude have been also taken into consideration during the calculation of hazard parameters. The earthquake hazard in the whole NW Himalaya region has been calculated in 28 seismogenic source zones delineated on the basis of seismicity level, tectonics and focal mechanism. The annual probability of exceedance of earthquake (activity rate) of certain magnitude is also calculated for all seismogenic source zones. The obtained earthquake hazard parameters were geographically distributed in all 28 seismogenic source zones to analyze the spatial variation of localized seismicity parameters. It is observed that seismic hazard level is high in Quetta-Kirthar-Sulaiman region in Pakistan, Hindukush-Pamir Himalaya region and Uttarkashi-Chamoli region in Himalayan Frontal Thrust belt. The source zones that are expected to have maximum regional magnitude (M max ) of more than 8.0 are Quetta, southern Pamir, Caucasus and Kashmir-Himanchal Pradesh which have experienced such magnitude of earthquakes in the past. It is observed that seismic hazard level varies spatially from one zone to another which suggests that the examined regions have high crustal heterogeneity and seismotectonic complexity.
Pure and Applied Geophysics, 1997
The Indian subcontinent is one of the most seismic prone areas of the world. The Himalayan mountains in the north, mid-oceanic ridges in the south and earthquake belts surrounding the Indian plate all show that the subcontinent has undergone extensive geological and tectonic processes in the past. The probability of the occurrence of earthquakes with magnitude 6 BM b B7 during a specified interval of time has been estimated on the basis of four probabilistic models namely Lognormal, Weibull, Gamma and Exponential distribution for the Indian subcontinent. The seismicity map has been prepared using the earthquake catalogue from the period 1963 -1994, and six different zones have been identified on the basis of clustering of events. The model parameters have been estimated by the method of maximum likelihood estimates (MLE) and method of moments (MOM). A computer program package has been developed for all four models, which represents the distributions of time intervals fairly well. The logarithmic of likelihood (ln L) is estimated for testing the models and different models have been found to be plausible. The probability of different magnitude thresholds has been evaluated using the Gutenberg-Richter formula Log N= a −bM for magnitude distribution. The constants a and b have been computed for each region and found to be varying between 5.46 -8.53 and 0.87-1.34, respectively.
Probabilistic seismic-hazard estimation for peninsular India
Bulletin of the Seismological Society of …, 2007
Peninsular India (10.0° N28.0° N; 68.0° E90.0° E) is one of the oldest and seismically most stable landmasses of the Indian plate. Recent seismic history, however, shows that more than five damaging earthquakes with magnitudes greater than M w 6.0 have occurred in this ...
New approaches for seismic hazard studies in the Indian subcontinent
Geomatics, Natural Hazards and Risk, 2013
Earthquakes constitute among the most feared natural hazards and these occur with no warning which can result in great destruction and loss of lives, particularly in developing countries. One way to mitigate the destructive impact of such earthquakes is to conduct a seismic hazard assessment and take remedial measures. This article aims at demonstrating significant contributions in the field of seismic zonation and microzonation studies in the Indian subcontinent. The contributions in the field of earthquake hazard have been very valuable and beneficial not only for science but also for society. The historical seismicity and seismic zonation studies as well as the present scenario of seismic hazard assessment in the Indian subcontinent, whether through probabilistic or deterministic approaches, are discussed. It has been found that many parts of the Himalayan region have peak acceleration values exceeding 0.6g. The epicentral areas of the great Assam earthquakes of 1897 and 1950 in northeast India represent the maximum hazard with acceleration values reaching 1.2-1.3g. The peak velocity and displacement in the same region is estimated as 120-177 cm s 71 and 60-90 cm, respectively. To mitigate seismic risk, it is necessary to define a correct response in terms of both peak ground acceleration and spectral amplification. These factors are highly dependent on local soil conditions and on the source characteristics of the expected earthquakes. This article will also present the findings of site-specific hazard assessment in megacities.
MOJ Civil Engineering
Earthquakes, the most dangerous and destructive natural hazards in the globe, manifest themselves in the form of vibrations of the earth which are caused by the sudden release of strain that has accumulated over time. Recent years have witnessed an increase in awareness about earthquake and their causes and mitigations. Seismic Hazard analysis is a method of quantifying the area in terms of topographical and seismological data. In the present paper, an attempt has been made to estimate seismic hazard at bedrock level in terms of PGA using state of art, probabilistic seismic hazard analysis. A detailed catalogue of historical and recent seismicity, within 300 km radius around the headquarter has been compiled and new seism tectonic map has been generated for the region. The completeness of the data should be checked before carrying out hazard analysis. Finally earthquake data analyzed statistically and the seismicity of the region around district headquarter Dantewara of Chhattisgarh, India, has been evaluated by defining 'a' and 'b' parameters of Gutenberg-Richter recurrence relationship. For district headquarter Dantewara, Values of the Peak Ground Acceleration (P.G.A.) for M100 Earthquake, has been estimated. The outcome of the research in the present paper, clearly indicate that the maximum (Peak Ground Acceleration) PGA values for the site of Dantewara, was obtained, due to fault No. 8.
Journal of Earth System Science, 2008
A comprehensive analytical as well as numerical treatment of seismological, geological, geomorphological and geotechnical concepts has been implemented through microzonation projects in the northeast Indian provinces of Sikkim Himalaya and Guwahati city, representing cases of contrasting geological backgrounds — a hilly terrain and a predominantly alluvial basin respectively. The estimated maximum earthquakes in the underlying seismic source zones, demarcated in the broad northeast Indian region, implicates scenario earthquakes of M W 8.3 and 8.7 to the respective study regions for deterministic seismic hazard assessments. The microzonation approach as undertaken in the present analyses involves multi-criteria seismic hazard evaluation through thematic integration of contributing factors. The geomorphological themes for Sikkim Himalaya include surface geology, soil cover, slope, rock outcrop and landslide integrated to achieve geological hazard distribution. Seismological themes, namely surface consistent peak ground acceleration and predominant frequency were, thereafter, overlaid on and added with the geological hazard distribution to obtain the seismic hazard microzonation map of the Sikkim Himalaya. On the other hand, the microzonation study of Guwahati city accounts for eight themes — geological and geomorphological, basement or bedrock, landuse, landslide, factor of safety for soil stability, shear wave velocity, predominant frequency, and surface consistent peak ground acceleration. The five broad qualitative hazard classifications — ‘low’, ‘moderate’, ‘high’, ‘moderate high’ and ‘very high’ could be applied in both the cases, albeit with different implications to peak ground acceleration variations. These developed hazard maps offer better representation of the local specific seismic hazard variation in the terrain.
Probabilistic Evaluation of Seismic Hazard in India: Comparison of Different Methodologies
2012
In view of the major advancement made in understanding the seismicity and seismotectonics of this region in recent times, an updated probabilistic seismic hazard map of India covering 6°–38° N and 68°–98° E was prepared and presented in this paper. In present analysis, three types of seismic sources, viz. linear, areal and zoneless models were considered and different attenuation relations were used for different tectonic provinces. The study area was divided into small grids of size 0.1° x 0.1° and the PHA and Sa values were evaluated at the centre of each grid point. A MATLAB code has been developed to estimate the hazard using linear sources and zoneless approach whereas CRISIS software was used to model areal sources. Comparison of different methodologies is presented in the paper. The linear source model predicts higher hazard compared to other two source models and Zoneless approach gives the lower value of hazard at a particular grid point. For most of the cities, gridded sei...