Browsing by Author "Himanshu Mittal"

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Characteristics of earthquake ground motions governing the damage potential for Delhi and the surrounding region of India
(Elsevier Ltd, 2023) Himanshu Mittal; Babita Sharma; Sandeep; Ambikapathy Ammani
The proximity of Delhi and the surrounding region to the active faults along with its geographical settings is a subject of discussion to comprehend the seismic resilience of the capital region of India. The region may be affected by the far-field earthquakes from the Himalayas as well as the near-field earthquakes associated with the local seismic activity. Considering the ordinary settings of this region, the present study is an insight to differentiate the damage potential of ground motion associated with near and far-field conditions to further see their consequences to understand the comprehensive seismic hazard of the region. The acceleration and velocity response analysis of recorded strong ground motions from far-field and near-field earthquakes exhibit a clear distinct behavior in the form of amplification and corresponding predominant period. The comparison of estimated normalized spectral accelerations with that of the seismic design code of the Bureau of Indian Standards (BIS), shows that the current Indian building design code is within the structural limits proposed for the seismic forces of long periods, however, exceeded amplitude of the normalized Spectral Acceleration for far-field earthquakes may be attributed towards the damage potential for the high rise buildings in the capital region of India. On the other hand, near-field earthquakes do not meet the criteria with the design code of BIS at lower periods from 0.02s to 0.09s along with the amplified Spectral acceleration. It also suggests that the structural heterogeneities within the subsurface of Delhi and the surrounding region have a strong bearing in contributing to the impact of seismic waves from near-field earthquakes producing short-period waves that may be disastrous for low-rise buildings. Based on the results, the study region affected by the distinct seismicity patterns is important to understand the shaking behavior of the different kinds of infrastructures/buildings in case of near-field and far-field earthquakes to appropriately utilize the information for constructing new buildings and strengthening the existing infrastructures in Delhi and the surrounding region of India. © 2023 The Authors
Development of region specific earthquake early warning scaling relations for the Garhwal region using observed and simulated datasets: a step forward to disaster mitigation
(Springer Science and Business Media B.V., 2024) Suraj Kumar Pal; Sandeep; Shubham Gangajali; Parveen Kumar; Himanshu Mittal
The Garhwal region, situated in the central segment of the Himalayas, stands as one of the most seismically active areas in the Uttarakhand Himalaya. The newly established earthquake early warning (EEW) system in the Garhwal region emphasizes the critical need for magnitude scaling relations to enable real-time estimation of earthquake size. This study employs P-wave onset data from both observed and simulated records to develop magnitude scaling relations specific to the Garhwal region. Initially, we modified the semi-empirical technique (SET) for P-wave simulation and validated this modification using the 1991 Uttarkashi (Mw6.8) and 1999 Chamoli (Mw6.4) earthquakes in the Garhwal region. The modified semi-empirical technique (MSET) demonstrates its reliability, as evidenced by the comparatively low root mean square error (RMSE) between observed and simulated records for both earthquakes. Subsequently, we apply MSET to simulate seven additional future earthquakes (Mw7.0–8.5) at the hypocentral locations of the 1991 Uttarkashi and 1999 Chamoli earthquakes. Moreover, conventional EEW parameters, such as average period (τc) and peak amplitude displacement (Pd), are extracted from 107 observed and 63 simulated P-wave onsets, utilizing a 3 s time window. Using this combined dataset of observed and simulated data, we introduce magnitude scaling relations based on the τc and Pd parameters. Subsequently, the developed scaling relations are tested to predict earthquake magnitude using the average values of estimated EEW parameters. The relatively small errors, measuring at 4.47–0.75%, and 2.45–0.60% for τc–Mw and 5.71–1.60% and 4.90–1.57% for Pd–Mw scaling relations, respectively for the Uttarkashi and Chamoli earthquakes suggest the applicability of these proposed relations. However, the scaling relations developed tend to underestimate the magnitude of earthquakes larger than 7.5, potentially attributed to the saturation observed in these relations for big earthquakes. Additionally, the calculated lead time for future earthquakes will range from 4 to 60 s for the sites situated within epicentral distances of 56–200 km. This lead time has the potential to play a substantial role in disaster mitigation in the Garhwal region, especially in the Indo-Gangetic plains and Himalayan foothills. Hence, the development of scaling relations specific to the region is imperative for effective disaster mitigation and risk reduction in the Garhwal region. © The Author(s), under exclusive licence to Springer Nature B.V. 2024.
Earthquake Genesis and Earthquake Early Warning Systems: Challenges and a Way Forward
(Springer Science and Business Media B.V., 2022) Roshan Kumar; Himanshu Mittal; Sandeep; Babita Sharma
Abstract: Several natural hazards, including earthquakes, may trigger disasters and the presence of disaster drivers further lead to the massive loss of life and property, every year around the world. The earthquakes are unavoidable, as exact earthquake prediction in terms of date, and time is difficult. However, with the advancement in technology, earthquake early warning (EEW) has emerged as a life-saving guard in many earthquake-prone countries. Unlike other warning systems (where hours of warning are possible), only a few seconds of warning is possible in the EEW system, but this warning may be very helpful in saving human lives by taking the proper action. The concept of EEW relies on using the initial few seconds of information from nearby instruments, performing basic calculations, and issuing the warning to the farther areas. A dense network or enough network coverage is the backbone of an EEW system. Because of insufficient station coverage, the estimated earthquake location is error-prone, which in turn may cause problems for EEW in terms of estimating strong shaking for the affected areas. Seismic instrumentation for EEW has improved significantly in the last few years considering the station coverage, data quality, and related applications. Many countries including the USA, Mexico, Japan, Taiwan, and South Korea have developed EEW systems and are issuing a warning to the public and authorities. Several other countries, namely China, Turkey, Italy, and India are in process of developing and testing the EEW system. This article discusses the challenges and future EEW systems developed around the world along with different parameters used for EEW. Article Highlights: This article aims to provide a comprehensive review related to the developmentThe explicit emphasis is on the scientific development of EEW parametersThe challenges and future scopes for the effective implementation of EEWS are discussed in terms of the correct location, the magnitude estimation, the region-specific use of ground motion prediction equations, communication technologies, and general public awareness © 2022, The Author(s), under exclusive licence to Springer Nature B.V.
Estimation of Source and Spectral Decay Parameters for Local Earthquakes in Siang Region of Arunachal Himalaya and Its Implication to the Tectonics and Crustal Heterogeneity
(Birkhauser, 2024) Amritansh Rai; Himanshu Mittal; G.P. Singh
In our study, we estimated earthquake source parameters and spectral decay characteristics of 378 seismograms corresponding to 80 small earthquake events with magnitudes ranging from 1.5 to 3.5. These earthquakes occurred between July 2011 and May 2012 in the Siang region of the Arunachal Himalaya which is not well-studied. To estimate source parameters, the classical Brune model is employed and through the analysis, a scaling relationship is established between the estimated corner frequency (fc) and seismic moment (M0), which can be expressed as M0=1×1022fc-3.18. This relationship is in close agreement with previous studies conducted in the Arunachal and Himachal Himalaya regions. It provides support for deviations from self-similarity in the study area, offering valuable insights into the tectonics and structural heterogeneity beneath the Arunachal Himalaya. Our analysis revealed variations in source radius, ranging from 154.4 m to 312.6 m, and seismic moment, spanning from 2.37 × 1011 N-m to 9.32 × 1013 N-m. Interestingly, we observed an increasing trend in stress drop, ranging from 0.013 MPa to 3.26 MPa, within the same range of seismic moment. This significant variation in stress drop primarily occurs in the upper 10–15 km of the Earth’s crust, indicating shear brittle failure in this upper crustal region. Furthermore, we conducted an in-depth examination of spectral parameters, including fc high-cut frequency (fmax), and high-frequency spectral decay parameter kappa (κ). Our study highlighted the dependence of κ and fmax estimates on both source characteristics and propagation path, with the source having the most substantial influence. This observation was substantiated through statistical analyses. Additionally, we explored the effect of recording site characteristics on κ and observed a significant contribution of shallow geology at the recording site. This was evident through a negative correlation between the site component of κ (κ0) and VS30, indicating that the local geology of the recording site plays a significant role in spectral parameter estimation. Based on our comprehensive data analysis and statistical observations, we conclude that the variations in source and decay parameters for earthquakes of different magnitudes are attributed to the diverse structural heterogeneities and complex seismotectonic processes underlying the Arunachal Himalaya region. © The Author(s), under exclusive licence to Springer Nature Switzerland AG 2024.
India’s Earthquake Early Warning Systems: A Review of Developments and Challenges
(Springer Science and Business Media B.V., 2025) Himanshu Mittal; Shanker Pal; Rajiv Siva Sai Kumar; Atul Saini; Yih-Min Min Wu; Ambikapathy Ammani; Ramesh Chandra Patel; Sandeep Arora; Om Prakash Mishra
The risk of earthquakes and their effects on both nature and infrastructure in seismically active regions of India require adaptable and scalable earthquake early warning (EEW) systems. Developing a robust EEW system is crucial to mitigate earthquake risks in the region, but it is a challenging task. Various institutes have attempted to develop EEW systems using different methods. Still, there is no common consensus, and issues remain with response time and reliability of disseminated information to the public. Efforts by institutions like the Indian Institute of Technology, Roorkee, have advanced EEW technologies, focusing on dense seismic sensor networks, real-time data processing algorithms, and effective dissemination mechanisms. Recent initiatives aim to improve sensor sensitivity and accuracy through fast communication systems for quicker earthquake detection. However, challenges persist in making EEW accessible and affordable, particularly in remote areas, due to the lack of a nationwide system. The National Centre for Seismology (NCS), under the Ministry of Earth Sciences (MoES), is piloting an EEW system in the NW Himalayas, which could lead to a nationwide implementation. Developing region-specific algorithms for rapid data analysis and nurturing collaboration between academic institutions, government agencies, and international partners are crucial steps. Public awareness campaigns and educational programs are essential for community resilience and timely response to earthquake alerts. Establishing a robust EEW system in India could significantly enhance earthquake risk mitigation efforts in earthquake-prone zones of the country and should be viewed within the context of a holistic risk reduction framework. EEW systems can enhance mitigation efforts, but they must be complemented by other essential measures, such as improving building resilience and promoting public awareness. © The Author(s), under exclusive licence to Springer Nature B.V. 2025.
Investigation of the high frequency attenuation parameter kappa (κ) beneath the volcanic region of Kyushu using surface and borehole dataset
(Elsevier Ltd, 2025) Sandeep; Sonia Devi; Pragya Singh; Udai Pratap Singh; Shiv Kumar Pal; Parveen Kumar; Monika; Ashok M.Praveen Kumar; Himanshu Mittal
This study focuses on a detailed analysis of the high-frequency attenuation parameter, kappa (κ), to better understand seismic wave propagation in the volcanic region of Kyushu. In this analysis, κ values are examined beneath the volcanic area of the Kyushu region using strong motion data from the 2016 Kumamoto earthquake. The Surface and borehole data are utilized to evaluate the effects of site conditions and regional attenuation characteristics, respectively. The site attenuation parameter (κ0) ranges from 0.022s to 0.068s, as estimated from 21 surface stations. The κ0 values correlate with average shear-wave velocity in the top 30 m (VS30), showing a decrease as VS30 increases. Additionally, using borehole data, the region-specific S-wave quality factor (Qs) and κ0 are estimated in this region, resulting in values of 846 ± 75 and 0.050 ± 0.002s, respectively. The relatively lower Qs values and higher κ0 values observed in this study may be due to the extensive volcanic activities in the Kyushu region. The findings closely match previous studies, highlighting significant attenuation in the volcanic region. The average κ values for borehole data are 0.043s–0.053s for horizontal components (κH) and 0.038s–0.051s for vertical components (κv). Surface data shows κH values from 0.061s to 0.070s and κV from 0.039s to 0.046s. A relative comparison shows κH and κv are roughly equal in borehole conditions, while surface conditions reveal κH exceeds κv due to site effects on horizontal components. The estimated κ values are crucial for future site-specific seismic hazard analysis in Kyushu's volcanic regions. © 2025 Elsevier Ltd
New Magnitude Scaling Relations for the Taiwan Region Utilizing Peak Acceleration, Peak Velocity and Bracketed Cumulative Absolute Velocity of P-Wave Onset Using Magnitude (M) 4.0–7.6
(Taylor and Francis Ltd., 2025) Suraj Kumar Pal; Sandeep; Parveen Kumar; Monika; Pragya Singh; Himanshu Mittal
The existing magnitude scaling relation using the average period (τc) and peak displacement amplitude (Pd) for Taiwan region often overestimates M4.0–5.0, causing false M ≥ 6 alarms. We propose new scaling relations using peak acceleration (Pa), peak velocity (Pv), and bracketed cumulative absolute velocity (BCAV) from P-wave onsets. Testing on M4.0–4.9 events shows that new relations exceed M ≥ 6 in 22% of cases, compared to 96% for existing relations. A maximum magnitude difference of 0.68 between cataloged and predicted magnitudes for M5.0–7.6 events confirm the applicability of the new relations. These relations would reduce false alarms and enhance disaster mitigation in Taiwan. © 2025 Taylor & Francis Group, LLC.
Preface
(Springer Science and Business Media B.V., 2023) Sandeep; Parveen Kumar; Himanshu Mittal; Roshan Kumar
[No abstract available]
Seismic Source Characteristics and Scaling Relations in the Northwest Himalayan Region: Case Study of Himachal Pradesh & Uttarakhand
(Birkhauser, 2024) Shikha Vashisth; Ambikapathy Ammani; Himanshu Mittal; Uma Shankar; O.P. Mishra
The Himachal Pradesh and Uttarakhand areas are known for their high seismic activity in India. According to the Bureau of Indian Standards, the areas are situated in seismic zones IV and V, and have the potential to produce small to large earthquakes. These areas have also seen significant seismic events in the past. To accurately and reliably estimate the seismic hazard and simulate the characteristics of strong ground motion in the region, it is essential to evaluate the source characteristics of earthquakes and their scaling relationships. Our investigation involved the estimation of earthquake source parameters and high-frequency spectrum decay parameters using 1059 seismograms, corresponding to 247 earthquake events with magnitudes ranging from 3.0 to 5.5 that occurred in the Himachal Pradesh and Uttarakhand regions of the Northwest Himalaya between 2010 and 2020. The classic Brune’s model is used to estimate source parameters. The relationship can be expressed as M0=2×1015fc-2.316 for Himachal Pradesh and M0=2×1016fc-3.445 for Uttarakhand region, which agrees with previous studies given for the study region, providing vital insights into tectonics and structural heterogeneity beneath the respective regions of Northwest Himalaya. Our analysis revealed that for earthquakes in Himachal Pradesh, the source radius of circular fault ranges from 42 to 771 m, whereas, for events in the Uttarakhand region, it varies from 48 to 437 m. Additionally, the seismic moment ranged from 2 × 1011 N-m to 9.93 × 1015 N-m for Himachal Pradesh and 1.11 × 1011 N-m to 1.40 × 1016 N-m for Uttarakhand events. An increasing trend in stress drop is observed, varying from 0.0026 MPa to 8.66 MPa for Himachal Pradesh and 0.0014 MPa to 9.51 MPa for Uttarakhand, within the similar range of seismic moment. Moreover, the study highlighted that the estimation of κ and fmax is influenced by both source characteristics and propagation path, with the source exerting a significant impact. A detailed analysis of the data suggests that the differences in how earthquakes start and fade in Himachal Pradesh and Uttarakhand are due to the complex geological structures and the intricate earthquake processes in these regions. © The Author(s), under exclusive licence to Springer Nature Switzerland AG 2024.
Seismic Source Characteristics and Scaling Relations in the Northwest Himalayan Region: Case Study of Himachal Pradesh & Uttarakhand
(Birkhauser, 2025) Shikha Vashisth; Ambikapathy Ammani; Himanshu Mittal; A. Akilbasha; Om Prakash Mishra
The Himachal Pradesh and Uttarakhand areas are known for their high seismic activity in India. According to the Bureau of Indian Standards, the areas are situated in seismic zones IV and V, and have the potential to produce small to large earthquakes. These areas have also seen significant seismic events in the past. To accurately and reliably estimate the seismic hazard and simulate the characteristics of strong ground motion in the region, it is essential to evaluate the source characteristics of earthquakes and their scaling relationships. Our investigation involved the estimation of earthquake source parameters and high-frequency spectrum decay parameters using 1059 seismograms, corresponding to 247 earthquake events with magnitudes ranging from 3.0 to 5.5 that occurred in the Himachal Pradesh and Uttarakhand regions of the Northwest Himalaya between 2010 and 2020. The classic Brune’s model is used to estimate source parameters. The relationship can be expressed as M0=2×1015fc-2.316 for Himachal Pradesh and M0=2×1016fc-3.445 for Uttarakhand region, which agrees with previous studies given for the study region, providing vital insights into tectonics and structural heterogeneity beneath the respective regions of Northwest Himalaya. Our analysis revealed that for earthquakes in Himachal Pradesh, the source radius of circular fault ranges from 42 to 771 m, whereas, for events in the Uttarakhand region, it varies from 48 to 437 m. Additionally, the seismic moment ranged from 2 × 1011 N-m to 9.93 × 1015 N-m for Himachal Pradesh and 1.11 × 1011 N-m to 1.40 × 1016 N-m for Uttarakhand events. An increasing trend in stress drop is observed, varying from 0.0026 MPa to 8.66 MPa for Himachal Pradesh and 0.0014 MPa to 9.51 MPa for Uttarakhand, within the similar range of seismic moment. Moreover, the study highlighted that the estimation of κ and fmax is influenced by both source characteristics and propagation path, with the source exerting a significant impact. A detailed analysis of the data suggests that the differences in how earthquakes start and fade in Himachal Pradesh and Uttarakhand are due to the complex geological structures and the intricate earthquake processes in these regions. © The Author(s), under exclusive licence to Springer Nature Switzerland AG 2024.
Source Modeling of Deep Plate Boundary 2021 Miyagi Earthquake (Mw7.0) Employing Modified Semi-Empirical Technique with Site Effects: A Step Forward Towards Hazard Mitigation
(Taylor and Francis Ltd., 2025) Sonia Devi; Pal Suraj Kumar; Sandeep Arora; Kumar Parveen; Monika; Himanshu Mittal
The source modeling of 2021 Miyagi earthquake (Mw7.0) offers a significant tool to understand the initial evaluation of M9 earthquake cycle in this region. This article seeks to simulate the 2021 Miyagi earthquake (Mw7.0) using the modified semi-empirical technique (MSET) after incorporating site effects determined using the Horizontal to Vertical spectral ratio technique. We propose the best-fitting source model of this earthquake from a spectrum of rupture model parameters using MSET. We believe that this effort is the first to use MSET to model this earthquake and will provide significant contribution for seismic hazard assessment of the Miyagi region. © 2024 Taylor & Francis Group, LLC.
Spatial Distribution of Stress Orientation by Inversion of Focal Mechanism Solutions Using MSATSI: A Case Study Across Japan Trench
(Springer Science and Business Media Deutschland GmbH, 2023) Sucheta Das; Sandeep; Sonia Devi; Himanshu Mittal; Praveen Kumar; Monika
Estimation of stress field orientations is a necessary aspect for recognition of crustal mechanics as well as the physics behind occurrence of earthquakes. A case study employing the new MATLAB software package Spatial And Temporal Stress Inversion (SATSI) for stress inversion utilizing the focal mechanism data is presented here to produce stress orientation models in Northeast (NE) Japan. In this work, the study region is divided into 49 small sub-regions so that the stress tensors and focal mechanisms can independently fit in each sub-region. Determination of any stress variation is strongly needed by the data while eliminating the artifacts due to overfitting of noisy or nonuniquely fitting data. To resolve it, a damped inversion procedure was applied which inverted the stresses in all sub-regions, while at the same time reducing the difference in stress between adjacent sub-regions. Earthquake focal mechanisms have been used to determine the stress patterns at depths capable of generating earthquakes in NE Japan since 1960–2021. In this work, 0D, 1D, and 2D stress inversion using the MSATSI (MATLAB package for Spatial And Temporal Stress Inversion) routine was performed and examined the spatial variation of stress orientations over NE Japan along the Japan Trench and put forward recent knowledge about the stress pattern. From the obtained 2D inversion results, a spatially varying stress regime is observed in the crust which demonstrates normal faulting on the subducting Pacific plate which changes to reverse faulting on the Okhotsk plate through an intermediate state of oblique faulting. © 2023, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.