Moment magnitude – local magnitude relationship for the earthquakes of the Shillong-Mikir plateau, Northeastern India Region: a new perspective

Baruah, Santanu; Baruah, Sanjib; Kalita, Aditya; Biswas, Rajib; Gogoi, N.; Gautam, J. L.; Sanoujam, Manichandra; Kayal, J. R.

doi:10.1080/19475705.2011.596577

Cited by 11 publications

(5 citation statements)

References 28 publications

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“…It also shows the results from a regression with a fixed slope equal to 1 (e.g., Ristau 2009, Gasperini et al 2013). The regression estimated a difference ( M –M L ) of 0.453, which was in the range (about −0.6 to 0.6) found for different regions and depths from past studies (e.g., Uhrhammer et al 1996, Ristau et al 2003, Atkinson and McCartney 2005, Braunmiller et al 2005, Ristau et al 2005, Wu et al 2005, Clinton et al 2006, Ristau 2009, Baruah et al 2012). Based on the regression, Naraghiaraghi et al's (2016) model for Iran had the fewest errors and so was adopted in this study to convert M L to M .…”

Section: Introductionsupporting

confidence: 55%

Multivariate Conversion of Moment Magnitude for Small-to-Moderate-Magnitude Earthquakes in Iran

et al. 2018

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Homogeneous estimates of moment magnitude (M) for small-to-moderate-magnitude (SMM) earthquakes are important to assess regional ground motion compared to global models. However, an estimate of M was available for only 6% of the shallow crustal earthquakes in Iran from 1973 to 2013 in the database developed by the Pacific Earthquake Engineering Research Center. Therefore, this study evaluates the existing conversion models, from ML, Ms, and m b, to M, for M > 4.0 using the Iranian data set. Correlations between the residuals of these conversions were computed. A weighted estimate for M is presented that combines these conversion models using these correlations based on multivariate statistics. The conversion to M was improved with smaller standard deviations, especially when ML and m b were both available. The inverse-variance–weighted approach, which is common in practice, underestimates the standard deviations because it neglects the positive correlations between these variables.

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Section: Introductionsupporting

confidence: 55%

Multivariate Conversion of Moment Magnitude for Small-to-Moderate-Magnitude Earthquakes in Iran

et al. 2018

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“…The 16 solutions include 14 CMT solutions of earthquakes Mw ! 4.9 (www.usgs.gov) and two waveform inversion solutions of smaller events Mw $ 3.6-3.7 computed by Baruah et al (2012b). For both methods, the inversion results are very consistent and show a NNW-SSE horizontal compressional stress and an ESE-WSW low angle or near horizontal tensional stress (figure 3 and table 2).…”

Section: Tectonic Stress Regime and Coulomb Stress Changementioning

confidence: 56%

“…The August 1988 earthquake also shows a strike-slip mechanism. The local broadband network in Assam valley, foredeep of the eastern Himalaya, recorded two small earthquakes with Mw 3.6-3.7 in 2002 at the southern end of the Tista fault and these events also show strike-slip mechanisms (Baruah et al 2012a(Baruah et al , 2012b figure 1). …”

Section: Earthquake Source Zone In the Sikkim Himalayamentioning

confidence: 99%

The September 2011 Sikkim Himalaya earthquake Mw 6.9: is it a plane of detachment earthquake?

Baruah

Saikia

Baruah

et al. 2014

Geomatics, Natural Hazards and Risk

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The 18 September 2011 Sikkim Himalaya earthquake of Mw 6.9 (focal depth 50 km, NEIC report) with maximum intensity of VII on MM scale (www.usgs. gov) occurred in the Himalayan seismic belt (HSB), to the north of the main central thrust. Neither this thrust nor the plane of detachment envisaged in the HSB model, however, caused this strong devastating earthquake. The EngdahlHilst-Buland (EHB) relocated past earthquakes recorded during 1965-2007 and the available global centroid moment tensor) solutions are critically examined to identify the source zone and stress regime of the September 2011 earthquake. The depth section plot of these earthquakes shows that a deeper (10-50 km) vertical fault zone caused the main shock in the Sikkim Himalaya. The NW (North-West) and NE (North-East) trending transverse fault zones cutting across the eastern Himalaya are the source zones of the earthquakes. Stress inversion shows that the region is dominated by horizontal NNW-SSE (North of North-West-South of South-East) compressional stress and low angle or near horizontal ENE-WSW (East of North-East-West of South-West) tensional stress; this stress regime is conducive for strike-slip faulting earthquakes in Sikkim Himalaya and its vicinity. The Coulomb stress transfer analysis indicates positive values of Coulomb stress change DS f for failure in the intersecting deeper fault zone that produced the four immediate felt aftershocks (M ! 4.0).

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“…Another magnitude for shallow and distant earthquakes, is surface wave magnitude Ms. Moment magnitude scale (M W ), is a relatively new scale which has the advantage of being used for measurement of larger earthquakes, unlike the Richter amplitude based scales (Baruah et al 2012).…”

Section: Magnitudementioning

confidence: 99%

Critical evaluation of seismic activities in Africa and curtailment policies – a review

Alaneme

Okotete

2018

Geoenviron Disasters

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The present paper discusses the seismicity of Africa and the need for the implementation of vibration control strategies in Africa, erroneously considered as aseismic. The review catalogues information on the seismicity of Africa, attesting that virtually every region in the African continent has come under the threat of some form of seismic event. The magnitudes and intensities of these seismic activities has resulted in devastations, including: loss of lives, building and civil structures collapse, displacements of people, economic losses, psychological traumatization, and grave fear. Evidences available show that most of the devastations are accentuated by tremor induced collapse of buildings and civil structures. It is thus imperative for substantive, simply implementable, and sustainable proactive measures for controlling the threats of seismic events be discussed within the African context. Current mitigation strategies in Africa include the establishment of seismic codes which govern the design of civil structures. The challenge to the implementation and the effectiveness of the existing African seismic codes was briefly discussed, and new measures which can reduce seismic risks were also highlighted The submissions of the paper is envisaged will create awareness on the budding seismic activities in Africa and awaken relevant authorities on the need for timely and practicable mitigation strategies to be in place to avert the attendant catastrophes associated with seismic occurrences.

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Moment magnitude – local magnitude relationship for the earthquakes of the Shillong-Mikir plateau, Northeastern India Region: a new perspective

Cited by 11 publications

References 28 publications

Multivariate Conversion of Moment Magnitude for Small-to-Moderate-Magnitude Earthquakes in Iran

Multivariate Conversion of Moment Magnitude for Small-to-Moderate-Magnitude Earthquakes in Iran

The September 2011 Sikkim Himalaya earthquake Mw 6.9: is it a plane of detachment earthquake?

Critical evaluation of seismic activities in Africa and curtailment policies – a review

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