The 28 April 2021 Kopili Fault Earthquake (Mw 6.1) in Assam Valley of North East India: Seismotectonic Appraisal

Dey, Chandan; Baruah, Santanu; Abdelwahed, Mohamed F.; Saikia, Sowrav; Molia, Nabajyoti; Borthakur, Prachurjya; Chetia, Timangshu; Bharali, Bubul; Dutta, N. C.; Phukan, Manoj K.; Paul, Avik; Saitlunga,; Hazarika, Devajit; Kayal, J. R.

doi:10.1007/s00024-022-03072-2

Cited by 7 publications

(8 citation statements)

References 50 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Spectral analysis of the S-phase of PUC [Figure 4], SKH [Figure 5], and LLI [Figure 6] shows the average moment magnitude of 4.2 Mw, average stress drop ∆σ 0.75MPa, the low average source radius (r) of 1697.6m, and a corner frequency of 0.75HZ. The attenuation factor for the calculation of spectral parameters makes a difference in the moment magnitude estimated from spectral analysis and the waveform inversion (4) . The stress drop study of the Ladakh-Karakoram zone from the spectral analysis showed the overall low-stress drop in the region which is significant in understanding the tectonic in the region (5) .…”

Section: Spectral Analysismentioning

confidence: 99%

“…The Broadband seismometer was Trillium (T40) recorded earthquake events at a sampling rate of 100Hz. The Northeastern regions are highly seismically active and are in Zone V of the seismic zoning map of India indicating that NE India is in the highest risk zone (4) . The Broadband seismic station installed within Mizoram is very significant for contributing to acquiring earthquake events up to a small tremor that occurs around the Indo-Burma regions.…”

Section: Introductionmentioning

confidence: 99%

“…The Broadband seismic station installed within Mizoram is very significant for contributing to acquiring earthquake events up to a small tremor that occurs around the Indo-Burma regions. Spectral analysis and waveform inversion technique were used to determine the source parameters of the 28 th April Kopili fault earthquake Mw 6.1 in Assam Valley of Northeast India (4) . The estimation of stress before and after an earthquake is a crucial parameter for understanding the accumulated stress over the fault regions which determines the size of an earthquake (5).…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Earthquake Source Mechanism and Source Parameters Determination Using Broadband Seismometer

Ralte,

Lalhmingsangi,

Saitluanga

et al. 2023

IJST

View full text Add to dashboard Cite

Objective:The main objective of the study is to obtain precise and accurate sources and mechanisms of earthquakes which is a prerequisite for understanding physical processes with the associated fault generating an earthquake. Methods: The technique of waveform inversion and Seisan software are used for the study of source mechanism and hypocentral parameters. Spectral parameters for estimation of earthquake source parameters can be achieved through the software EQK_SRC_PARA. Findings: The obtained spectral parameters have been used to estimate source parameters such as seismic moment (Mo), Spectral corner frequencies (fc), Source radii (r), and stress drops (∆σ ). From this study, the earthquake was a shallow focus earthquake at a depth of 40km and duration magnitude Md 4.3. Spectral analysis of the S-phase results in the average moment magnitude 4.2Mw which is different from the magnitude recorded by USGS which is 4.7Mb, stress drop ∆σ 0.75MPa, average source radius (r)1697.6m, and average corner frequency (fc) 0.75Hz. Waveform inversion results in moment magnitude Mw 2.7 from the combined stations whereas single seismic waveform inversion from the PUC station results in a moment magnitude of 3.6Mw. Novelty: Determination of earthquake source parameters and mechanisms with more seismic data is significant for improving the current understanding of the dynamic processes governing earthquakes.

show abstract

Section: Spectral Analysismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Earthquake Source Mechanism and Source Parameters Determination Using Broadband Seismometer

Ralte,

Lalhmingsangi,

Saitluanga

et al. 2023

IJST

View full text Add to dashboard Cite

show abstract

“…The 28 April 2021 foredeep earthquake Mw 6.1 occurred at the northern end of the Kopili Fault in the Assam valley (Figure 3), and it caused severe shaking, damage to the weak structures, ground liquefaction, fractures, and so on resulting in maximum intensity VII within a radius of 50 km (Dey et al, 2022). The GCMT solution with a centroid depth at 39 km shows strike‐slip faulting, and the NW trending northeast dipping nodal plane is conformable with the Kopili Fault (Figure 3; Hazarika & Kayal, 2022) inferred this event to the Kopili Fault, that occurred by right‐lateral strike‐slip movement.…”

Section: Recent Strong Earthquakes In the Eastern Himalayasmentioning

confidence: 99%

“…(b) A tectonic model shows the N-S seismic crosssection across the 2011 main shock source zone with the near vertical Tista Fault where the main shock and four immediate aftershocks (red stars) occurred; the past significant earthquakes are shown in black stars. (c) N-S cross-section of lower magnitude aftershocks of the 2011 mainshock recorded by a semi-permanent microearthquake network in the main shock epicentre area (after Kumar et al, 2012) caused severe shaking, damage to the weak structures, ground liquefaction, fractures, and so on resulting in maximum intensity VII within a radius of 50 km (Dey et al, 2022). The GCMT solution with a centroid depth at 39 km shows strike-slip faulting, and the NW trending northeast dipping nodal plane is conformable with the Kopili Fault (Figure 3; inferred this event to the Kopili Fault, that occurred by right-lateral strike-slip movement.…”

Section: Seismotectonics Of the 2021 Assam Foredeep Earthquake Mw 61mentioning

confidence: 99%

Recent large and strong earthquakes in the eastern Himalayas: An appraisal on seismotectonic model

et al. 2022

Self Cite

View full text Add to dashboard Cite

Since 1934, two great earthquakes (Mw ≥8.0) and some eight large/strong earthquakes (Mw 6.5–7.8) occurred in the eastern Himalayas, from eastern Nepal to the Eastern Himalayan Syntaxis (EHS) Zone. All these events are instrumentally recorded by local as well as by the global network. From west to east these events are the 2015 two large/devastating earthquakes (Mw 7.8 and 7.3, respectively) in eastern Nepal, the 1934 and 1988 Bihar–Nepal earthquakes (Mw 8.1 and 6.8, respectively), the 2011 Sikkim (Mw 6.9), the 1967 and 2009 Bhutan (Mw 6.5 and 6.3, respectively), 1964 and 1947 Arunachal–Tibet (Mw 6.5 and 7.0, respectively), and the 1950 Assam–Tibet great (Mw 8.4) earthquakes. Most recently, on 28 April 2021, an earthquake Mw 6.1 occurred in the Assam foredeep. These events are documented as shallow (0–20 km) Main Himalayan Thrust (MHT) earthquakes in the International Seismological Center and National Earthquake Information Center—USGS catalogues. With the advent of local digital seismic networks and better precision of hypocentre locations, the eastern Himalayan earthquake source zones are found to be much different; these are not typically MHT events. Precise hypocentre locations indicate bimodal seismicity at shallower (0–20 km) as well as at deeper depths (40–70 km) in the eastern Himalayas. Seismic cross‐sections and fault plane solutions of the earthquakes do not support a uniform seismotectonic model for the entire Himalayas. All the instrumentally recorded past great earthquakes in the Himalayas and the recent destructive earthquakes in the eastern Himalayas study region are critically examined in view of the known seismotectonic model, and we suggest that each large/great earthquake occurred in its own unique complex tectonic environment. The transverse structures play a major role in generating the deeper earthquakes in the eastern Himalayas and the EHS; the shallower MHT may be flattened.

show abstract

First hand observations from the April 28, 2021 Sonitpur (MW 6.4) earthquake, Assam, India: possible mechanism involved in the occurrence of widespread ground effects

et al. 2023

View full text Add to dashboard Cite

The 28 April 2021 Kopili Fault Earthquake (Mw 6.1) in Assam Valley of North East India: Seismotectonic Appraisal

Cited by 7 publications

References 50 publications

Earthquake Source Mechanism and Source Parameters Determination Using Broadband Seismometer

Earthquake Source Mechanism and Source Parameters Determination Using Broadband Seismometer

Recent large and strong earthquakes in the eastern Himalayas: An appraisal on seismotectonic model

First hand observations from the April 28, 2021 Sonitpur (MW 6.4) earthquake, Assam, India: possible mechanism involved in the occurrence of widespread ground effects

Contact Info

Product

Resources

About