G. Suresh

National Centre for Seismology · Ministry of Earth Sciences

The 3-D distributions of b-value of the frequency-magnitude distribution and fractal correlation dimension (D2) of seismically active Uttarakhand Himalayan seismic zone is presented. For this study, a catalogue of 525 local earthquakes was used (ML 1.0–5.5) during 2017–2020. The de-clustered catalog is found to be complete above ML=2.6. The b-value...

Here, we present crustal and lithospheric structure at six broadband stations below the Palghar swarm activity region, Maharashtra, India, which has produced 7786 events of ML0.4–4.7 during November 2018–March 2020. The crustal thicknesses are modelled through the Differential Evolution (DE) waveform inversion of radial P-receiver functions (PRFs),...

Since the initial collision at 55 Ma, rocks of the Indian crust below the Himalayas have undergone modification chemically and compositionally due to the ongoing India–Asia convergence. The local earthquake tomography images a shallow (~ 1–2°) north-easterly dipping low-velocity layer (10–20% drop in Vp and Vs, 10–15% increase in Vp/Vs) beneath the...

We study source parameters of 10 local earthquakes (2.7 ≤ \(M_{w}\) ≤ 4.5) that have occurred in the National Capital Region (NCR) since 2001 and the ground motions produced by these events. Moment rate spectra of the earthquakes retrieved from the recordings at hard sites after applying corrections for geometrical spreading (1/R, R ≤ 100 km), anel...

A local magnitude scale has been developed for Eastern Dharwar Craton (EDC) and adjoining areas around Southern Peninsular Shield, India, to improve the scale used previously in this region. Measurements, 1333 of peak amplitudes on simulated Wood-Anderson instruments located in Andhra Pradesh and Telangana (APTS) network for 91 earthquakes recorded...

Far away landslide detection A mass wasting and flood event on 7 February 2021 in Uttarakhand, India, killed more than 200 people and damaged two hydropower plants. Cook et al . discovered that teleseimic signals from the beginning of this event were recorded at different stations on a regional seismic network in northern India. The signals were ob...

Source parameters were estimated using multiple empirical Green’s functions (meGf) method for 2 clusters of shallow depth and small-magnitude earthquakes induced by the infiltration due to gravity into the groundwater zone after heavy monsoons during October 1998 and October 2017, in Hyderabad, South India. First, four decades of earthquake catalog...

The present work focuses on the three-dimensional mapping of fractal correlation dimensions and b-values of the Palghar (Maharashtra) and Pulichintala (Andhra Pradesh) regions of the Indian shield. The study is done using catalogues of 8766 Palghar earthquakes of ML0.4–4.7 and 965 Puclichintala earthquakes of ML ranging from −0.4 to 4.6. The b-valu...

We image the lateral variations in the Moho depths and average crustal composition across the Kumaon–Garhwal (KG) Himalaya, through the H–K stacking of 1400 radial PRFs from 42 three-component broadband stations. The modelled Moho depth, average crustal Vp/Vs, and Poisson’s ratio estimates vary from 28.3 to 52.9 km, 1.59 to 2.13 and 0.17 to 0.36, r...

The data set contains seismic waveforms recorded by the 17 broadband stations of Uttarakhand network operated by CSIR-NGRI (Srinagesh et al., 2019) for a period of 3 hours each, covering the 7 Feb 2021 Uttarakhand landslide event (Rao et al., 2021). The stations are equipped with 24-bit Reftek Digital acquisition system 120 sec broadband Reftek sen...

The National Seismological Network (NSN) of India has a history of more than 120 yr. During the last two decades, the NSN has gone through a significant modernization process, involving installation of seismic stations equipped with a broadband seismograph (BBS) and a strong-motion accelerograph (SMA). Each station has a very-small-aperture termina...

a moderate-sized earthquake (M L * 4.6) located in the Palnadu sub-basin of Cuddapah basin was felt both in the states of Telangana and Andhra Pradesh. The earthquakes prior and after the M L 4.6 are located close to the thrust and along the periphery of the backwaters of the Pulichintala Reservoir. About 965 earthquakes in the magnitude range of 0...

We evaluated seismic background noise at national network in India using PSD, Fourier spectra, Spectrogram, and HVSR approach, before and during the nationwide lockdown declared due to COVID-19 pandemic. The analyses were performed to understand characteristics of noise wave-field in such unprecedented situation and its effect on site response at t...

An earthquake of small magnitude (ML3.5) occurred on 12 April 2020 near the east district boundary of NCT, Delhi with maximum PGA for the event observed to be 14.13 gals. A few smaller aftershocks also occurred in the area. The estimated fault plane solution of the mainshock suggests normal faulting with some strike slip component. The focal mechan...

Standard spectral ratio (SSR) technique has limited applicability in the estimation of spectral amplification in the vast Indo-Gangetic plains (IGP). Here we take recourse to an alternative approach using the recordings of three largest aftershocks of the 2015 Gorkha earthquake (Mw 7.9). We separately compute geometric mean source spectrum of an ev...

Earthquake monitoring for seismological research and in India started as early as 1898 with the installation of the first seismological observatory at Alipore, Kolkata. Since then, with the worldwide development of earthquake monitoring seismographs, the Indian national seismological network has expanded, and currently, there are 115 observatories,...

This is the e-supplement to the following paper Gahalaut et al (2016) Seismological, geodetic, macroseismic and historical context of the 2016 Mw 6.7 Tamenglong (Manipur) India earthquake, Tectonophysics, 688, doi: 10.1016/j.tecto.2016.09.017

We map the dis­tri­b­u­tion of macro­seis­mic in­ten­si­ties from the Mw 6.9 Kani and the Mw 6.8 Chauk in­tra-slab earth­quakes in 2016 in Myan­mar us­ing the 1998 Eu­ro­pean Macro­seis­mic Scale (EMS-98) by in­ter­pret­ing data gath­ered from field sur­veys, com­mu­nity re­sponses sent via so­cial me­dia to the Myan­mar Earth­quake Com­mit­tee (ME...

Abstract: Using detailed waveform analysis of Pn, sPn depth phases from the nearby seismic stations, attempts were made to resolve the focal depth of the 2011 Sikkim earthquake.The focal depth of 46.8 km thus determined was found closer to the GCMT source mechanism solution as compared to ISC solution(29.6 km). Re-examination of its source mechanis...

In this report, we present results of the analysis of seismic data recorded at the Sriramsagar observatory for the period from January to December 2017. Our analysis shows that during this period 16 micro-earthquakes occurred with magnitudes ranging between M 0.7 to M 3.0. These earthquakes are located using data from this observatory along with ot...

Using detailed waveform analysis of Pn, sPn depth phases from the nearby seismic stations, attempts were made to resolve the focal depth of the 2011 Sikkim earthquake. Focal depth of 46.8 km thus determined was found closer to the GCMT source mechanism solution as compared to ISC solution (29.6 km). Re-examination of its source mechanism with the s...

The 2017 Guptkashi earthquake occurred in a segment of the Himalayan arc with high potential for a strong earthquake in the near future. In this context, a careful analysis of the earthquake is important as it may shed light on source and ground motion characteristics during future earthquakes. Using the earthquake recording on a single broadband s...

On 3 January 2017, a Mw 5.6 earthquake occurred in Dhalai district in Tripura (India), at 14:39:03 IST (09:09:03 UTC) with an epicentre at 24.018°N ± 4.9 km and 91.964°E ± 4.4 km, and a focal depth of 31 ± 6.0 km. The focal mechanism solution determined after evaluating data from seismological observatories in India indicated a predominantly strike...

The hazard posed by large dams has long been known. Although no damshave failed due to an earthquake, instances of significant damages to dams have occurredworld wide. To quote a few, the 12th May, 2008 (M 8) Sichuan Earthquake, China caused damage to over 1000 concrete and embankment dams and reservoirs in addition to over400 hydropower plants in...

The CSIR-National Geophysical Research Institute (NGRI), Hyderabad has been monitoring earthquake activity around Sriramsagar (SRS) reservoir since nearly three decades on the request of the then Government of Andhra Pradesh. A seismic station at Sriramsagar was necessiated when an earthquake of M 3.2 was felt on July 21, 1984. Although, the Penins...

We analyze ground motions produced by the 25 April 2015 Gorkha, Nepal, earthquake (Mw 7.9) and five of its larger aftershocks (5:3 ≤ Mw ≤ 7:2) which were recorded in the distance range 100-900 km by two recently installed strong-motion networks in the Indo-Gangetic Plains (IGP). In comparison with the largest Mw 7.2 aftershock, we find that the pea...

The National Geophysical Research Institute (NGRI), Hyderabad has been monitoring earthquake activity around Nagarjunasagar (NJS), and Srisailam (SLM) reservoirs since more than three decades on the request of the Government of Andhra Pradesh. Although, the Peninsular Shield of India typically signifies a stable continental crust, well away from ac...

Online Material: Table of PGAs and PGVs during the 21 May 2014 ( M w 6.1) Bay of Bengal earthquake at Central Indo‐Gangetic Plains network (CIGN) stations. The arcuate shape Himalayan collision zone is one of the most seismically active regions of the world. Five M ∼8 earthquakes have occurred in the last 120 years: 1897 Meghalaya, 1905 Kangra, 19...

The eastern Himalayan and Indo-Burman plate boundary systems are dis- tinct from the rest of the India-Eurasia continental collision, due to oblique convergence across two orthogonal plate boundaries resulting in a zone of distributed deformation both within and away from the plate boundary. To understand the seismotectonics of this region we model...

We measure the inter-station Rayleigh and Love wave phase velocities across the northwestern Indian Peninsular shield (NW-IP) through crosscorrelation and invert these velocities to evaluate the underneath crust and upper mantle velocity structure down to 400 km. We consider a cluster of three stations in the northern tip of the Peninsula and anoth...

Various developmental activities like installation of hydroelectric projects, multipurpose projects, nuclear power plants, rapid urbanization and industrial growth needs mapping seismically active faults and correlating with the regional tectonics. This is the present day demand from the society to seismologists at large. To meet this demand the ag...

Deep focus earthquakes within the underthrust Indian lower crust beneath the Himalaya occur in very specific regions and have distinct source characteristics. The study of the source mechanisms of these earthquakes provides valuable constraints on the kinematics of deformation of the underthrust Indian Plate, and its influence on the active deforma...

The Eastern Himalayan System (east of 88°E) is distinct from the rest of the India-Eurasia continental collision, due to a wider zone of distributed deformation, oblique convergence across two orthogonal plate boundaries and near absence of foreland basin sedimentary strata. To understand the seismotectonics of this region we study the spatial dist...

The process of dealing with earthquake disasters essentially involves three most important and inter-dependent components - (i) comprehensive understanding of the earthquake generation processes and the interior of the earth, (ii) disaster mitigation and preventive measures, and (iii) work through the ultimate goal of earthquake prediction. The bas...

In this article efforts have been made to describe how education and awareness programme on seismograph setup helps the school students to learn more about the occurrence of earthquakes and safety measures to be adopted during the earthquake. Soon after the Bhuj earthquake of January 26, 2001, a mission mode project in seismology was initiated by t...

Through inversion of fundamental mode group velocities of Love and Rayleigh waves, we study the crustal and subcrustal structure across the central Deccan Volcanic Province (DVP), which is one of the world's largest terrestrial flood basalts. Our analysis is based on broadband seismograms recorded at seismological station Bhopal (BHPL) in the centr...

We examine the source mechanism and depth of the largest known earthquake to have occurred in the Sikkim-Darjeeling Himalaya, the 2011 September 18 earthquake (Mw = 6.9) and its aftershocks (greater than mb 3.5). The mainshock has been well recorded by the global digital seismic network (in the distance range of 30-80˚), while our local network of...

Though the Delhi earthquake of 27 August 1960 is important in understanding seismic hazard to the city, there is an uncertainty associated with its reported epicentre, depth and magnitude. The reported epicentres given in different catalogues are not consistent with felt and damage reports, and the depths (58–109 km) are also inconsistent with reco...

The 14 April 2012 earthquake of Mw 4.8 is the best monitored event in the Koyna region, a globally significant site of reservoir triggered seismicity in western India. Hence, investigation of this event assumes great importance, also considering its epicentral location close to that of the 1967 Koyna earthquake of M 6.3, the world’s largest reservo...

The Bay of Bengal evolved along the eastern margin of the Indian subcontinent about 130 Ma with the breakup of India from eastern Gondwanaland. Since then the Indian lithospheric Plate has moved northward, along with the Bay of Bengal, and eventually collided with the Eurasian Plate. The age of the lithosphere beneath the central Bay of Bengal is ˜...

P and S receiver functions (PRFs and SRFs, respectively) for 21 broad-band seismograph stations of the India Meteorological Department (IMD) illuminate lithosphere and the underlying mantle of some previously poorly sampled regions of the Indian sub-continent. Our analysis demonstrates that the Archean and Early Proterozoic lithospheric keel of the...

In this paper, we report that the ratio of broadband energy (0.01–2 Hz) to high-frequency energy (0.3–2 Hz), E r, estimated from regional seismograms of India, might be a useful parameter in estimating tsunami potential of earthquakes in the Sumatra–Andaman region. E r is expected to be sensitive to the depth as well as to the source characteristic...

Nanded city in Maharashtra is a part of the Godavari river basin and is located about 3 km north of the Godavari river. The Godavari river basin is bounded by the Manjira Tectonic Zone to the south and the Pranahita Godavari Graben to the north, both structures trending along the NW–SE direction. Further, the NW–SE trending Kadam fault lies to the...

Site amplifications at over 100 sites in the frequency range of 0.1–10Hz were investigated in and around Jabalpur city of central India using the conventional Nakamura technique of computing H/V spectral ratios, to estimate the predominant frequencies and corresponding amplifications at each site. To validate these results, Multichannel Analysis of...

Although the Indo-Gangetic basin is adjacent to rupture areas of large Himalayan earthquakes (M >= 6), a quantitative study of the amplification of seismic waves in the region is still lacking. To obtain a first estimate of the amplification, for two years we operated an array of 10 broadband seismographs that crossed the central Indo-Gangetic basi...

The existence of elastic anisotropy in the crust of the continental shelf adjoining the northwest Deccan Volcanic Province (DVP) is obtained through inversion of group velocities of Rayleigh and Love waves at periods of 5-80 s. An isotropic crustal model fairly explains the adjoining onshore surface-wave velocity data, but a radially anisotropic cr...

The lithospheric velocity structure of the lower Indus basin has been evaluated through inversion of fundamental modes of both Love and Rayleigh wave group velocities from the broadband records of a seismic network maintained by the Institute of Seismological Research, Gujarat (India).We have considered three clusters of wave paths A, B, and C that...

The Delhi earthquake of 25 November 2007 (Mw 4.1) is the best recorded local event ever. Peak ground acceleration (PGA) at seven sites in the epicentral zone ranged between 7 and 118 Gal. An analysis of the earthquake leads to the following conclusions. (1) It occurred at a depth of 30 km and involved strike–slip faulting with some normal component...

We study source characteristics of two small, local earthquakes which occurred in Delhi on 28 April 2001 (Mw3.4) and 18 March 2004 (Mw2.6). Both earthquakes were located in the heart of New Delhi, and were recorded in the epicentral region by digital accelerographs. The depths of the events are 15km and 8km, respectively. First motions and waveform...

Interstation phase velocities of surface waves are measured through a cross-correlation method across the Bastar craton in the eastern part of the Indian peninsula. The periods of Love waves lie between 15 and 91 sec and those of Rayleigh waves lie between 13 and 104 sec. The observed phase velocities are close to the theoretical dispersion curves...

Andhra Pradesh state in the southern peninsular India has a low to moderate seismic hazard. The state falls in seismic zones II and III (as per Bureau of Indian standards map 2002). The capital city of Hyderabad lies in zone II. The area under southeastern districts of Chittoor, Nellore and Kadapa come under zone III. Districts of Godavari and Kris...

Attenuation of seismic waves is very essential for the study of earthquake source parameters and also for ground-motion simulations, and this is important for the seismic hazard estimation of a region. The digital data acquired by 16 short-period seismic stations of the Delhi Telemetric Network for 55 earthquakes of magnitude 1.5 to 4.2, which occu...

The Indus block in the Northwest Indian subcontinent is a continental area lying between the Chaman fault in the west, the Aravalli range in the east, and the main boundary fault of Himalaya in the north. We evaluate the lithospheric structure of this crustal block through inversion of Love-and Rayleigh-wave group velocities obtained using broadban...

With the aim of ground-motion estimation in the region of Jabalpur, India, which suffered serious damage during the 21 May 1997 earthquake (M-w 5.8), we analyze an event that occurred on 16 October 2000. This earthquake was recorded by broadband seismic stations of Jabalpur (JPBL, Delta = 45 km) and Rewa (REWA, A = 173 km), and a few other stations...

We present a preliminary source study of the Muzaffarabad earthquake of 8 October 2005 (Mw 7.6) and the far-field ground motions that it generated. Our analysis is based on regional broadband seismograms recorded at stations operated by the India Meteorological Department (IMD) which are situated to the south of the epicentre, and at non-IMD statio...

QC-estimates of Kachchh Basin in western India have been obtained in a high frequency range from 1.5 to 24.0 Hz using the aftershock data of Bhuj earthquake of January 26, 2001 recorded within an epicentral distance of 80 km. The decay of coda waves of 30 sec window from 186 seismograms has been analysed in four lapse time windows, adopting the sin...

Microtremor method is the most inexpensive and convenient technique for dynamic site characterization of sedimentary basins. This study was carried out in Delhi NCR at 32 different stations and field measurements were taken using velocity sensors for a period of 1 hr at each station point. The data was analyzed using SEISAN software for the estimat...

Only five moderate and large earthquakes (M w Ն5.7) in India—three in the Indian shield region and two in the Himalayan arc region—have given rise to multiple strong ground-motion recordings. Near-source data are available for only two of these events. The Bhuj earthquake (M w 7.6), which occurred in the shield region, gave rise to useful recording...

Only five moderate and large earthquakes (M-w greater than or equal to5.7) in India-three in the Indian shield region and two in the Himalayan arc region-have given rise to multiple strong ground-motion recordings. Near-source data are available for only two of these events. The Bhuj earthquake (M-w 7.6), which occurred in the shield region, gave r...

The September 30, 1993 earthquake that shook the Killari and nearby villages in the Latur district of Maharashtra caused extensive damage to property and an estimated loss of over 7600 lives. The event led to a critical review of the seismic status of the Indian Peninsular shield region, which was thought to be seismically a stable land mass. A num...