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Seismicity plot of Nepal Himalaya region illustrating seismicity around the Kathmandu. Grey circle shows the location of historical earthquakes occurred during 1971–2015 from USGS catalog. The tectonic is considered after Coleman and Hodges (1995)
Source publication
The destructive Mw = 7.8 Nepal earthquake happened in Nepal Himalaya, 80 km NW of Kathmandu city on 25 April 2015. A number of aftershocks in which one of them is Mw = 7.3 which occurred on 12 May 2015 are observed around the Kathmandu city of Nepal. In this paper, strong motion data of Nepal earthquake and its eight aftershocks having magnitude ra...
Citations
... Accordingly, a comprehensive earthquake inventory for the area within a 500 km radius of Sree Padmanabhaswamy Temple, located at 8.4°N and 76.9°E, has been assembled from numerous National and International sources for the period from 1819 to 2022 AD [62]. The Guaribidannur Array (GBA), Indian Meteorological Department (IMD), Indira Gandhi Centre for Atomic Research (IGCAR) and National Geophysical Research Institute (NGRI) [39] are among the national agencies and International Seismological Centre (ISC) data file and the US Geological Survey NEIC catalogue are two examples of the international organizations that served as the sources [36]. According to the US Nuclear Regulatory Commission (1977), earthquakes originating beyond the designated study area can contribute to the overall seismic hazard inside the study region. ...
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, sitespecific
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 same procedure is adopted at each station to estimate site ampliBcation. The site ampliBcation is an important input parameter for the estimation of Q, as site ampliBcation always inCuence the earthquake waveforms recorded at the surface (Joshi et al. 2014;Kumar et al. 2017Kumar et al. , 2018. Hence, for the estimation of attenuation relation, the strong motion records at each recording station are corrected for the obtained site eAects. ...
The frequency-dependent shear-wave quality factor and site amplification are computed simultaneously for the Garhwal region, NW Himalaya.A regional quality factor relationship of form, Qβ(f) = (102 ± 3.9)f(1.0±0.1) is established for the Garhwal Himalaya.The acceleration records corrected from the obtained site effect are used to develop attenuation relations at each recording station.The close resemblance of obtained Qβ(f) relations and the geology has been observed for the study region. The frequency-dependent shear-wave quality factor and site amplification are computed simultaneously for the Garhwal region, NW Himalaya. A regional quality factor relationship of form, Qβ(f) = (102 ± 3.9)f(1.0±0.1) is established for the Garhwal Himalaya. The acceleration records corrected from the obtained site effect are used to develop attenuation relations at each recording station. The close resemblance of obtained Qβ(f) relations and the geology has been observed for the study region. The frequency-dependent shear-wave quality factor (Qβ(f)) and site amplification are computed for the seismically and tectonically active Garhwal Himalaya. The inversion technique of strong motion data is applied to obtain Qβ(f) and site effect at each recording station. The strong motion data of 82 earthquakes recorded in the Garhwal region is used for the present inversion algorithm. The comparison of site effects obtained by the present inversion scheme and well developed H/V technique (H/V is the ratio of Fourier spectra horizontal to vertical components) shows that site effects computed through the inversion technique have close resemblance with these estimates from the H/V technique. Both horizontal components are used to establish the frequency-dependent Qβ(f) relations at each station. The values of ‘Qo’ and ‘n’ at different stations vary from 92 to 112 and 0.9 to 1.1, respectively. The close resemblance of obtained Qβ(f) relations at different stations suggest, the presence of almost similar type of lithology, i.e., hard rock at these stations. A regional quality factor relationship of form, Qβ(f) = (102 ± 3.9)f(1.0±0.1) is established for the Garhwal Himalaya based on modelled Qβ values of each station. This relationship reveals low Qo value (<200) and high n value (>0.8) for the Garhwal Himalaya, which correspond to tectonically and seismically active region.
... The source parameters of an earthquake such as the stress drop, seismic moment, source radius, and moment magnitude provide significant information for use in several fields, including (1) studies of earthquake source characteristics, (2) simulations of strong motion records (Boore, 1983;Bora et al., 2017;Devi et al., 2021;Hartzell & Heaton, 1986;Sandeep et al., 2020), (3) computations of shear wave quality factors by inversion of strong motion data (Joshi et al., 2012;Kumar et al., 2017Kumar et al., , 2015aKumar et al., , 2018, (4) estimations of rupture dimensions using empirical relationships (Ö ztürk, 2014;Wang & Tao, 2003;Wells & Coppersmith, 1994), and (5) calculations of the seismic energy released due to earthquake occurrences and the space-time variation of the stress drops of earthquakes (Raj et al. 2009;Borkar et al., 2013;Singh et al., 2018a). In the present work, the Brune (1970) model, which is based on the Eshelby (1957) model, is used to compute the source parameters from the source spectrum (Sato & Hirasawa, 1973;Madariaga, 1976;Hanks & Kanamori, 1979;Fletcher, 1982;Kaneko & Shearer, 2014. ...
... Various source parameters such as the magnitude, seismic moment, stress drop, corner frequency, and seismic energy released can be used to establish scaling relations. Researchers have carried out source parameter studies in the Himalaya region (Borkar et al., 2013, Kumar et al., 2006a, 2006b, 2018Joshi et al., 2014;Vandana et al., 2017;Mittal et al., 2020). The applicability of the present approach to the Kinnaur Himalaya makes this work novel. ...
Site and path effects are always required to isolate the source term from a recorded seismograph for the estimation of source characteristics. In this paper, the site and path effects are assessed in terms of site amplification and anelastic attenuation (quality factor), respectively, to obtain an isolated source term for the estimation of earthquake source parameters in the Kinnaur Himalaya. These terms are then applied to calculate the source parameters of 75 local earthquakes in the range 1.5 ≤ moment magnitude (Mw) ≤ 3.6 recorded in the Kinnaur region. The scaling relations of earthquake source parameters are also established for this region. The site amplification curves and S-wave quality factor Qs(f) are determined and further utilized to correct the Fourier spectrum of earthquake records. The obtained source spectrum corrected for these two terms is compared with the theoretical source spectrum based on the Brune (J Geophys Res 75:4997–5009, 1970) source model. The root-mean-square error (RMSE) between the observed and theoretical spectrum is formulated by implementing iterative forward modeling. The obtained range of source parameters of 75 events reveals ranges of 2.73 × 10¹¹–3.44 × 10¹⁴ N-m for seismic moment, 0.03–13 bar for stress drop, 0.3–0.9 km for source radius, and 5.64 × 10⁰²–1.19 × 10⁰⁸ J for radiated energy.
... b Geological and seismotectonic division of this region (map modified after Roy et al., 2015); the dotted blue rectangle represents the present study area. c Spatial distribution of the 2170 events used in the present study recorded during 1900-2010 (NCS, MoES) (modified after Sandhu et al., 2020) Table 1 Details of strong-motion stations used, predominant frequency observed from H/V curves, v 30 s calculated using the Kramer (1996) (Kumar et al., 2018;Kumari et al., 2020;Luzon et al., 2004;Narayan et al., 2002). Another example of the impact of local geology is the 2011 Sikkim earthquake (M w 6.9). ...
This study focuses on the validation and applicability of a recently modified semi-empirical technique (MSET) to integrate site effects. The improvement of MSET by considering site effects has been verified by the data of the 1988 Indo-Burma earthquake (Mw 7.2), which happened in the North Eastern Region (NER) in India. This technique is also used to model a future scenario earthquake (Mw 8.2) in the NER. The required site effects are estimated using Nakamura’s horizontal-to-vertical (H/V) ratio technique for 89 waveform records. The obtained site effects are further used to modify an existing semi-empirical technique. To validate this modification, the strong-motion records of the 1988 Indo-Burma earthquake are simulated for bedrock and surface conditions. Afterwards, the root mean square error (RMSE) of these records is compared with surface records obtained by 14 seismic stations. The records simulated at the surface are well validated well with observed ones as compared to the records simulated at bedrock and hence confirm the reliability of the MSET. The improved performance of the MSET after incorporation of site effects validates the approach of the present work and will prove to be significant for simulation of earthquake surface conditions in any region. Further, this improved MSET is used to simulate strong-motion records of a future scenario earthquake (Mw 8.2) with the same epicentral location. The iso-acceleration maps are prepared from simulated records for both cases (Mw 7.2 and 8.2), which provide peak ground acceleration (PGA) values of more than 500 and 1000, respectively, for near-field regions. The obtained results are of significant interest for seismic hazard assessment of NE India.
... Trillium 120 seismograph with Taurus digitizer was installed at each station with sampling frequency of 100 Hz. Firstly, base line correction is incorporated to the raw data (Boore and Bommer 2005;Joshi et al. 2010;Mittal et al. 2012Mittal et al. , 2013aSandeep et al. 2015;Kumar et al. 2018;Sandeep et al. 2019). An example of waveform data recorded at four BBS station is shown in Fig. 2. The earthquake data of magnitude 1.7 ≤ M w ≤ 4.4 occurred during the period of 2010-2012 in Nubra-Shyok region are implemented to study seismogenic snow avalanches in this region. ...
Snow avalanche can be triggered by different mechanisms including metrological conditions, snow pack stability together with external factor such as seismic tremor and explosions. The snow avalanche triggered by seismic event is very important hazard phenomena in the snow covered region. In the present paper, investigation of earthquake-induced snow avalanches is introduced in Nubra–Shyok region of Western Himalaya, India. Compilation of seismogenic snow avalanche and earthquakes occurred in the Nubra–Shyok region during the period of 2010–2012 is made, which reveals that out of 393 natural avalanches, 81 avalanches was triggered due to the earthquake during this period. The local earthquakes occurred in Nubra–Shyok region, recorded by a local seismic network, are utilized for this work. The same date of occurrence of earthquakes and snow avalanches confirm seismogenic snow avalanche in this region. In the present work, avalanches triggered due to natural seismicity during the period of 2010–2012 related with earthquakes of magnitude 1.7 ≤ Mw ≤ 4.4 and distance of induced snow avalanche from epicenter of earthquakes, i.e., 4–92 km. In this study, lower bound limits of earthquake magnitudes, which cause avalanches, are established up to the distance of 92 km. Relation between earthquake magnitude and distance of induced snow avalanche from epicenter reveals that an earthquake of magnitude 1.4 (Mw) can trigger a snow avalanche as distance approaches to zero from earthquake epicenter. The comparison of obtained relation with other similar types of studies, i.e., Keefer (Geol Soc Am Bull 95:406–421, 1984), Podolskiy et al. (J Glaciol 56(197):431–446, 2010a) confirms the reliability of the present work.
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.
The Kathmandu region becomes situated in a very close to the major thrust faults such as Main Boundary Thrust (MBT) and Main Central Thrust (MCT) has been significantly affected by series of several major earthquakes in the past. The current study analyses the attenuation of body waves in the region using the coda normalization method based on the data of two stations (NA430 and NA060) essentially from a temporary seismic network deployed after the occurrence of the 25th April 2015 earthquake. The events considered for the study have a local magnitude of 4–5.5 at a depth range of 10–27 Km. The estimated quality factor of primary and secondary waves are QP = (44 ± 12.896)f (0.82±0.173), QS = (62 ± 19.265)f (0.94±0.185) for NA430 station and QP = (35 ± 9.467)f (0.93±0.155), QS = (68 ± 22.510) f(0.91±0.198) for NA060 station. The QS/QP ratio more than one observed for the entire frequency range specify the highly heterogeneous crust medium beneath the study region. The obtained quality factors could be used in the generation of target ground motion for engineering purposes and in the calculation of source parameters for seismic hazard assessment as risk reduction strategies in the study region.
