Faculty Publications
Permanent URI for this communityhttps://idr.nitk.ac.in/handle/123456789/18736
Publications by NITK Faculty
Browse
9 results
Search Results
Item Challenges and opportunities for coastal reservoir development in India(Elsevier, 2020) Sitharam, T.G.; Kolathayar, S.In India, presently 320 million people remain in the water-starved parts of the country, and according to the United Nations, 840 million people are expected to be water-starved in India by 2050. Although there has been no significant change in India’s rainfall pattern, the number of areas under drought in India is increasing every year. Increase in population is one of the reasons for water scarcity, but inefficient management of the precipitation received stands as the major cause. Although extreme rainfall events are significantly increasing, there is a spatial nonuniformity in the rainfall events that occur. This makes it difficult to preplan large-scale water storage at different locations. Solution to India’s water problem lies in conserving the abundant monsoon water bounty by storing it in coastal reservoirs for future use. This paper focuses on the challenges and opportunities in India for storing river floodwaters in coastal reservoir. The paper also presents the concept of Sarovar Mala, a chain of coastal reservoirs, an innovative concept that has the potential to ensure water availability to India throughout the year. © 2020 Elsevier Inc.Item Synthesis of Linear JTFA-Based Response Spectra for Structural Response and Seismic Reduction Measures for North-East India(World Scientific, 2020) Devaraj, D.; Ramkrishnan, R.; Prabu, T.; Kolathayar, S.; Sitharam, T.G.North-East India (NEI) has a long history of devastating earthquakes due to the complicated tectonic setting of the region. A shortage of sufficient recorded time-histories from the region calls for a synthesis of accelerograms for dynamic analyses. In this study, a novel Joint Time-Frequency Analysis (JTFA) technique is adopted for the synthesis of accelerograms, considering the non-stationary behavior of earthquake waves. JTFA is used for analyzing the signals in a joint time and frequency domain to better understand its characteristics and synthesize signals without compromising its inherent characteristics like frequency content and amplitude. Synthetic accelerograms are developed using JTFA techniques for different magnitude and distance ranges between 5 to 6.8 and 0-480km and response spectra are developed. Synthesized generalized accelerograms and their response spectra are compared with actual signals in the same magnitude-distance ranges and were found to match. A comparison of the frequency contents of actual and synthetic signals was also carried out using Fourier Transforms and spectrograms (SPs) and was found to be in good agreement. Further, a comparative study of various earthquake reduction measures for NEI is carried out for a scenario earthquake using the synthesized data, and the best suitable structural input for the region is recommended. © 2020 World Scientific Publishing Company.Item Recent seismicity in Delhi and population exposure to seismic hazard(Springer Science and Business Media B.V., 2021) Kolathayar, S.This paper makes an attempt to review historical and recent seismicity in Delhi and presents updated seismic hazard map of Delhi integrated with ward-wise classified population data. Earthquakes are not destructive unless other factors that enhance the damage prevail. Population density and types or quality of buildings in an area are two such important factors that affect the risk during any hazards, particularly an earthquake. This paper presents the details of the seismic hazard analysis for Delhi with the latest available information on earthquakes and seismic sources within 300 km radius around the city, using state-of-the-art deterministic approach. Ten different attenuation relationships developed for the active tectonic region were considered in the present study. They were ranked using log-likelihood method. Ward-wise population maps along with classified population maps were developed based on the 2011 census data. Hazard contour map and population maps are presented in this paper to revisit the seismic risk prevailing in the region. An attempt was made to overlay the hazard map with population maps showing the distribution of various classes of the population that reflects the seismic risk exposure to different wards of Delhi. © 2021, The Author(s), under exclusive licence to Springer Nature B.V.Item Deterministic seismic hazard and landslide hazard zonation of Arunachal Pradesh(Springer, 2022) Anand, G.; Rahangdale, A.; Mantri, S.S.; Singh, S.; Kolathayar, S.This paper presents a seismically induced landslide hazard assessment for the state of Arunachal Pradesh, India, based on GIS techniques. A comprehensive earthquake catalog was prepared with data from various sources like USGS, ISC, etc., within a rectangular enclosure having a distance of 500 km in four cardinal directions from the Arunachal Pradesh state boundary. The catalog was homogenized in a unified moment magnitude scale. The earthquake data were collected for a period ranging from the 1500s to the year 2020. The earthquakes having a magnitude ≥4 are considered for this study as they are mainly responsible for inducing enough horizontal movement along the slopes for landslides. Considering the linear source model, the deterministic seismic hazard analysis was performed to estimate peak horizontal acceleration (PHA) at the bedrock level. The log-likelihood method was employed to decide the most efficient and reliable ground motion prediction equation (GMPE) for the Arunachal Pradesh region. Then peak ground acceleration (PGA) values generated at the surface due to the shaking of bedrock were calculated using a non-linear site amplification (considering the soil nature as B-type NHERP classification). The PGA values were considered to induce driving force on slopes, thus causing a landslide. The topographical slope map of Arunachal Pradesh was developed from CARTOSAT Digital Elevation Model Data (30m resolution). The study region was divided into 50 × 50 m2 grids. The seismically induced landslide hazard assessment was performed using Newmark’s methodology using PGA values and slope angles at the center of each grid. The critical factor of safety necessary to counter the landslide for corresponding PGA values was determined, and its spatial variation in the state is presented as contour maps. For any grid point in the study region, if the in-situ (available) static factor of safety is higher than the static factor of safety necessary to counter the landslide as predicted in the current study, that slope is regarded to be safe. © 2022, Indian Academy of Sciences.Item Seismic Hazard Assessment and Landslide Vulnerability Mapping for Ladakh, and Jammu & Kashmir Using GIS Technique(Springer, 2023) Bhagyaraj, U.; Kolathayar, S.In the present study, earthquake-induced landslide susceptibility mapping of the two newly formed union territories of India namely Ladakh, and Jammu & Kashmir has been done based on Newmark’s methodology using GIS techniques. The vulnerability of the study area against induced seismic acceleration was estimated in terms of static safety factor (FSc). Terrain slope and Peak Horizontal acceleration (PHA) were taken as the major input for the study. Deterministic Seismic Hazard Analysis (DSHA) was carried out by considering linear seismic source model to obtain PHA at the bedrock level using a MATLAB code developed by authors. The PHA was amplified to the ground surface using appropriate site correction factors considering the B-type site class. GIS technique was employed to get slope value from Digital Elevation Models (DEM). The two union territories were divided into 30m×30m grids and the static factor of safety values required to prevent the landslide for each grid were estimated. It is observed that both Ladakh, Jammu & Kashmir are at risk of landslides caused by earthquakes, as many spots demand a critical safety factor (FSc) of greater than 1.0. It is apparent that the upper western sections of Jammu & Kashmir, which include Muzaffarabad district and parts of Punch district, are severely prone to landslides since they require FSc greater than 2.0. In comparison to other regions, the lower western region of Ladakh, near India’s political border, is demanding a high value of FSc. The map thus developed is an excellent guide to researchers for detailed study and to policymakers for taking remedial actions. © 2023, Geological Society of India, Bengaluru, India.Item Preparedness for a forgotten disaster: A case study Coimbatore, India(Elsevier Ltd, 2024) Lalith Prakash, E.; Anand, K.B.; Kolathayar, S.Earthquake preparedness is known to effectively reduce the distressful effects of earthquakes, as demonstrated in experiences worldwide. This research aims to use a region-specific, valid, and reliable survey-based tool to assess individual and community earthquake preparedness levels in a densely populated city region with a forgotten earthquake history. The study focuses on evaluating the earthquake preparedness levels of a population in the Indian peninsular shield region that has not experienced an earthquake or received any preparatory program in their life time; but the region has an earthquake history. Coimbatore city was chosen for the same reason, and two survey-based tools were developed - the Individual Earthquake Readiness Index (IERI) and the Community Earthquake Readiness Index (CERI) - using a comprehensive literature analysis, questionnaire creation via focused group discussion followed by expert panel validation, and pilot studies. This study ensured the validity and reliability of the tools through content validity, construct validity, internal consistency test, Spearman's test-retest reliability test, Exploratory Factor Analysis (EFA), and Confirmatory Factor Analysis (CFA). The final IERI is a 27-item tool, and the final CERI is a 20-item tool. This study broadens the scope of risk assessment, facilitating a methodical estimation of Earthquake Readiness Index as one of the pivotal social vulnerability determinant. The study revealed a strong sense of community spirit in Coimbatore, but residents showed a lack of individual preparedness and were hesitant to take leadership roles. The findings emphasize the need for targeted interventions to bridge the gaps in earthquake preparedness, fostering a culture of proactive engagement and individual responsibility. © 2023Item Probabilistic Seismic Hazard Assessment and Liquefaction Potential Evaluation for Amaravati Capital Region(Springer, 2024) Kolathayar, S.; Ashrith, M.S.; Rukminikumar, S.The present study aims to evaluate the seismic hazard and liquefaction potential for Amaravati capital region (16° 4?–16° 49? N and 80° 7?–81° 2? E) using the latest earthquake data and in-situ geotechnical data. A state-of-the-art Probabilistic Seismic hazard assessment was carried out for the region, and PGA values were obtained for Maximum Credible Earthquake (MCE) and Design-Based Earthquake (DBE) levels, which are 2% and 10% probability of exceedance for 50 years corresponding to 2475 and 475 return periods, respectively. The maximum PGA values at the bedrock level obtained were 0.084 g and 0.172 g for DBE and MCE levels, respectively. Borehole data from 16 different locations were used in the analysis. Liquefaction potential was evaluated using the Seed and Idriss method considering SPT-N values at the site. Liquefaction hazard maps were developed for 3 m and 6 m depths for both MCE and DBE levels. It is observed that the Factor of safety (FoS) against Liquefaction is lesser for MCE ground motion, whereas FoS is higher for the DBE levels. The region was found to be safe against liquefaction for design-based earthquakes, whereas the liquefaction potential was found to be high for maximum credible earthquakes. © The Author(s), under exclusive licence to Indian Geotechnical Society 2024.Item Landslides and debris flow triggered by the July 2024 extreme rainstorm in the Chooralmala watershed in Wayanad, India(Springer Science and Business Media Deutschland GmbH, 2025) Kolathayar, S.; Menon, V.; Kundu, P.[No abstract available]Item Deterministic Seismic Hazard Analysis of Sree Padmanabhaswamy Temple, Kerala State(Springer, 2025) Padmanabhan, M.P.H.; Siddhardha, R.; Kolathayar, S.; Hegde, R.; Beekanahalli Mokshanatha, B.M.Deterministic seismic hazard analysis (DSHA) is a technique employed to estimate potential hazards and ground shaking resulting from specific earthquake scenarios at a given location. In the present study, DSHA is conducted for the Sree Padmanabhaswamy Temple, situated in the southernmost district of Kerala, India. This seismic hazard study is crucial due to the temple’s proximity to seismic events such as the 1900 AD Coimbatore earthquake with a magnitude of 6.3 Mw and the 2000 Pala earthquake with a magnitude of 4.7 Mw. This study examines earthquake data within a 500 km radius surrounding the Sree Padmanabhaswamy Temple in Thiruvananthapuram District, Kerala, from 1819 to 2022 AD. The seismic zone of the temple site is III according to the Indian zonation map (IS 1893 (Part 1): 2016), relying on past earthquakes recorded throughout India. The collected earthquake data underwent a homogenization process to determine the moment magnitude (Mw), distinguishing foreshocks and aftershocks from the main shocks. A seismotectonic map was developed comprising of geological discontinuities and 316 earthquakes events with moment magnitudes between 3.0 and 6.3 Mw. The software tools employed for this work include MATLAB, QGIS and ZMAP. The Log-likelihood technique (LLH) was used to choose the ground motion prediction equations (GMPEs) for the location. The GMPEs were then given weights based on the computed values of the data support index (DSI). The study region was partitioned into a grid size of 0.05° × 0.05° (5 km × 5 km). Using MATLAB code, the peak ground acceleration (PGA) was estimated for the site and PGA was found in the center of each grid cell, taking into account all seismic sources within a 500 km radius. In addition, site-specific deterministic spectrum was also developed. The findings show that Sree Padmanabhaswamy Temple has low seismicity, which is defined by weak to moderate earthquakes that have sources close to the temple. © The Author(s), under exclusive licence to Indian Geotechnical Society 2024.