A deterministic seismic hazard map of India and adjacent areas

Earthquake Spectra, 2006

Seismic hazard maps have been prepared for Northeast India based on the uniform hazard response spectra for absolute acceleration at stiff sites. An approach that is free from regionalizing the seismotectonic sources has been proposed for performing the hazard analysis. Also, a new attenuation model for pseudo-spectral velocity scaling has been developed by using 261 recorded accelerograms in Northeast India. In the present study, the entire area of Northeast India has been divided into 0.1°grid size, and the hazard level has been assessed for each node of this grid by considering the seismicity within a 300-km radius around the node. Using the past earthquake data, the seismicity for the area around each node has been evaluated by defining a and b values of the Gutenberg-Richter recurrence relationship, while accounting for the incompleteness of the earthquake catalogue. To consider the spatial distribution of seismicity around each node, a spatially smoothed probability distribution function of the observed epicentral distances has been used. Uniform hazard contours for pseudo-spectral acceleration as the hazard parameter have been obtained for an exposure time of 100 years and for 50% confidence level at different natural periods for both horizontal and vertical components of ground motion. The trends reflected by these contours are broadly consistent with the major seismotectonic features in the region.

Journal of Seismology, 2017

Current computational resources and physical knowledge of the seismic wave generation and propagation processes allow for reliable numerical and analytical models of waveform generation and propagation. From the simulation of ground motion, it is easy to extract the desired earthquake hazard parameters. Accordingly, a scenario-based approach to seismic hazard assessment has been developed, namely the neodeterministic seismic hazard assessment (NDSHA), which allows for a wide range of possible seismic sources to be used in the definition of reliable scenarios by means of realistic waveforms modelling. Such reliable and comprehensive characterization of expected earthquake ground motion is essential to improve building codes, particularly for the protection of critical infrastructures and for land use planning. Parvez et al. (Geophys J Int 155:489-508, 2003) published the first ever neo-deterministic seismic hazard map of India by computing synthetic seismograms with input data set consisting of structural models, seismogenic zones, focal mechanisms and earthquake catalogues. As described in Panza et al. (Adv Geophys 53:93-165, 2012), the NDSHA methodology evolved with respect to the original formulation used by Parvez et al. (Geophys J Int 155:489-508, 2003): the computer codes were improved to better fit the need of producing realistic ground shaking maps and ground shaking scenarios, at different scale levels, exploiting the most significant pertinent progresses in data acquisition and modelling. Accordingly, the present study supplies a revised NDSHA map for India. The seismic hazard, expressed in terms of maximum displacement (Dmax), maximum velocity (Vmax) and design ground acceleration (DGA), has been extracted from the synthetic signals and mapped on a regular grid over the studied territory.

Natural Hazards, 2007

A method of seismic zonation based on deterministic modeling of rupture plane is presented in this work. This method is based on the modeling of finite rupture plane along identified lineaments in the region using the semi-empirical technique, of Midorikawa [(1993) Tectonophysics 218:287–295]. The modeling procedure follows ω2 scaling law, directivity effects, and other strong motion parameters. The technique of zonation is applied for technoeconomically important NE part of Brahmaputra valley that falls in the seismic gap region of Himalaya. Zonation map prepared for Brahmaputra valley for earthquakes of magnitude M > 6.0 show that approximately 90,000 km2 area fall in the highly hazardous zone IV, which covers region that can have peak ground accelerations of order more than 250 cm/s2. The zone IV covers the Tezu, Tinsukia, Dibrugarh, Ziro, North Lakhimpur, Itanagar, Sibsagar, Jorhat, Golaghat, Wokha, Senapati, Imphal, and Kohima regions. The Pasighat, Daring, Basar, and Seppa region belong to zone III with peak ground accelerations of the order 200–250 cm/s2. The seismic zonation map obtained from deterministic modeling of the rupture is consistent with the historical seismicity map and it has been found that the epicenter of many moderate and major earthquakes fall in the identified zones.

Many earthquakes have been knowledgeable in Indian peninsular shield, which was previously treated to be seismically steady. Seismic risk assessment refers to an evaluation of ground motion parameters at a particular area by considering some past earthquake evidence. In the current study seismic risk assessment is performed for the " Gorakhpur " city. It is a highly seismic prone area. It comes under zone IV. The manuscript presents the resolve of peak ground acceleration (PGA) and maximum credible earthquake (MCE). MCE has been dogged by taking into account the local seismotectonic movement in a propos 350 km radius about Gorakhpur city. The seismic risk in provisions of peak horizontal acceleration was estimated to be 0.312g using attenuation model by " Sharma " (2000) and 0.032g using attenuation model by " Iyenger and Raghukanth " (2004). The calculated peak horizontal acceleration in the nearby reading is in verification with the observed values of Nepal earthquakes and is furthermore similar to standards reported in additional studies.

The present research paper reviews on the different seismic hazards variations in the country. All the thirty-two source zones of country covered into seven geological regions. A brief highlights of return period along with a review of past PSHA effects for estimating seismic hazard in India. Earthquake catalogue containing all unknown events of medium to large magnitudes are 4≤Mw<5, 5≤Mw<6, 6≤Mw<7, 7≤Mw<8 and 8≤Mw<9. After collecting earthquake raw data following process carried out to the preparation of earthquake data, Z-map used for declusturing the data, completeness of the catalogue and recurrence relation of Gutenberg-Richter's derived a frequency-magnitude recurrence relationship. Seismic hazard analysis describes the potential for earthquake related natural phenomena such as ground shaking, rupture of fault and soil liquefaction, Seismic hazard may be assessed deterministic and probabilistic approach. Deterministic Seismic Hazard Analysis (DSHA) involves the development of a particular seismic scenario consisting of an earthquake of a specified size occurring at a specified location in other words provides a straightforward frame work for evaluation of worst-case ground motion. The Peak Horizontal Acceleration (PHA), Peak Vertical Acceleration (PVA) and Peak Ground Acceleration (PGA) values obtained in the past study matches well with the values obtained by other authors studied for different area of the country.

Journal of Seismology, 2010

In this paper, ground motion during six past devastating earthquakes and one possible future event in the northeastern part of India is estimated by seismological approaches. Considering uncertainty in the input source parameters, a series of ground motions have been simulated. The peak ground acceleration (PGA) and response spectra at important cities and towns in the epicentral regions of these events are obtained. The PGA distribution over the entire northeastern region of India, encompassing the epicenter, is presented in the form of contours. The obtained results can be used for the seismic analysis and design of structures in this region.

International Journal of Engineering Research and, 2016

Many earthquakes have been knowledgeable in Indian peninsular shield, which was previously treated to be seismically steady. Seismic risk assessment refers to an evaluation of ground motion parameters at a particular area by considering some past earthquake evidence. In the current study seismic risk assessment is performed for the "Gorakhpur" city. It is a highly seismic prone area. It comes under zone IV. The manuscript presents the resolve of peak ground acceleration (PGA) and maximum credible earthquake (MCE). MCE has been dogged by taking into account the local seismotectonic movement in a propos 350 km radius about Gorakhpur city. The seismic risk in provisions of peak horizontal acceleration was estimated to be 0.312g using attenuation model by "Sharma" (2000) and 0.032g using attenuation model by "Iyenger and Raghukanth" (2004). The calculated peak horizontal acceleration in the nearby reading is in verification with the observed values of Nepal earthquakes and is furthermore similar to standards reported in additional studies.

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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.

Natural Hazards, 2010

The seismically active Northwest (NW) Himalaya falls within Seismic Zone IV and V of the hazard zonation map of India. The region has suffered several moderate (~25), large-to-great earthquakes (~4) since Assam earthquake of 1897. In view of the major advancement made in understanding the seismicity and seismotectonics of this region during the last two decades, an updated probabilistic seismic hazard map of NW Himalaya and its adjoining areas covering 28–34°N and 74–82°E is prepared. The northwest Himalaya and its adjoining area is divided into nineteen different seismogenic source zones; and two different region-specific attenuation relationships have been used for seismic hazard assessment. The peak ground acceleration (PGA) estimated for 10% probability of exceedance in 50 and 10 years at locations defined in the grid of 0.25 × 0.25°. The computed seismic hazard map reveals longitudinal variation in hazard level along the NW Himalayan arc. The high hazard potential zones are centred around Kashmir region (0.70 g/0.35 g), Kangra region (0.50 g/0.020 g), Kaurik-Spitti region (0.45 g/0.20 g), Garhwal region (0.50 g/0.20 g) and Darchula region (0.50 g/0.20 g) with intervening low hazard area of the order of 0.25 g/0.02 g for 10% probability in 50 and 10 years in each region respectively.