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Please use this identifier to cite or link to this item: http://repository.iitr.ac.in/handle/123456789/6481
Title: A seismic moment magnitude scale
Authors: Das R.
Sharma, Mukat Lal
Wason H.R.
Choudhury D.
Gonzalez G.
Published in: Bulletin of the Seismological Society of America
Abstract: The aim of obtaining a single scale for earthquake magnitudes has led many studies in the past to either develop relationships among various existing scales or develop an altogether new scale to represent a wide range of magnitudes on a single scale. Although a reliable and standardized estimation of earthquake size is a basic requirement for all tectonophysical and engineering applications, different magnitude scales estimate different values for the same earthquake, thereby making such studies inadequate. The moment magnitude (Mw) scale has been referred to by various researchers as the best scale, one that matches well with the observed surface-wave magnitudes with Ms ? 7.5 at a global level. The formulation and validation of the Mw scale were carried out considering the southern California region for lower and intermediate earthquakes. In this study, an endeavor has been made to extend the moment magnitude scale to include lower and intermediate magnitudes in a global context emphasizing the use of body waves, particularly P waves, in which data are abundant. We first investigate the degree of closeness of Mw values with other observed magnitudes (e.g., Ms and mb) for smaller and intermediate magnitude ranges considering global International Seismological Centre (ISC) and Global Centroid Moment Tensor (CMT) databases. To improve upon the consistency of the Mw scale for a wider range, a uniform generalized seismic moment magnitude scale Mwg log M0/1.36 – 12.68, for magnitudes ? 4.5, has been developed, considering 25,708 global earthquake events having mb and M0 values from ISC and Global CMT databases, respectively, during the period 1976–2006. The Mwg scale is also valid for 3:5 ? mb ? 7:0 because the relations between seismic moment and the magnitudes mb and Mwg are same. The greater accuracy of the Mwg scale over the Mw scale at different magnitudes (i.e., mb or Ms) is found to be statistically significant in the range including smaller and intermediate events. The similarity of the Mwg scale is also tested on 394 global seismic radiated energy values collected from Choy and Boatwright (1995). It is observed that 76% of estimated radiated energy values obtained through the Mwg scale show closer agreement (than with Mw) to the observed radiated energy values. Mwg is computed from low-and high-frequency spectra, and because it is consistent for small, intermediate, and large earthquake events, it will play a useful role as an earthquake magnitude estimator for all earthquake related studies. © 2019, Seismological Society of America. All rights reserved.
Citation: Bulletin of the Seismological Society of America (2019), 109(4): 1542-1555
URI: https://doi.org/10.1785/0120180338
http://repository.iitr.ac.in/handle/123456789/6481
Issue Date: 2019
Publisher: Seismological Society of America
ISSN: 371106
Author Scopus IDs: 35784195400
7403269008
6505940895
7103392045
56013579600
Author Affiliations: Das, R., National Research Center for Integrated Natural Disaster Management, Avenue Vicuña Mackenna 4860, La Florida Región Metropolitana Santiago, Macul, Chile, Departamento de Ciencias Geológicas, Universidad Católica del Norte, Avenida Angamos 0610, Antofagasta, Chile
Sharma, M.L., Earthquake Engineering Department, Indian Institute of Technology Roorkee, Roorkee, Uttarakhand 247667, India, National Research Center for Integrated Natural Disaster Management, Avenue Vicuña Mackenna 4860, La Florida, Región Metropolitana Santiago, Macul, Chile, Departamento de Ciencias Geológicas, Universidad Católica del Norte, Avenida Angamos 0610, Antofagasta, Chile
Wason, H.R., Earthquake Engineering Department, Indian Institute of Technology Roorkee, Roorkee, Uttarakhand 247667, India, National Research Center for Integrated Natural Disaster Management, Avenue Vicuña Mackenna 4860, La Florida, Región Metropolitana Santiago, Macul, Chile, Departamento de Ciencias Geológicas, Universidad Católica del Norte, Avenida Angamos 0610, Antofagasta, Chile
Choudhury, D., Department of Civil Engineering, Indian Institute of Technology Bombay Powai, Mumbai, 400076, India, National Research Center for Integrated Natural Disaster Management, Avenue Vicuña Mackenna 4860, La Florida, Región Metropolitana Santiago, Macul, Chile, Departamento de Ciencias Geológicas, Universidad Católica del Norte, Avenida Angamos 0610, Antofagasta, Chile
Gonzalez, G., Departamento de Ciencias Geológicas, Universidad Católica del Norte, Avenida Angamos 0610, Antofagasta, Chile, National Research Center for Integrated Natural Disaster Management, Avenue Vicuña Mackenna 4860, La Florida, Región Metropolitana Santiago, Macul, Chile
Funding Details: The article has benefitted from funding by the Fondo de Financiamiento de Centros de Investigación en Áreas Prioritarias (FONDAP) (Centro Nacional de Investigación para la Gestión Integrada de Desastres Naturales [CIGIDEN]) Grant Number 15110017. The authors are grateful to the reviewers for their critical reviews and constructive suggestions, which helped improve technical content significantly. The authors are grateful to Editor-in-Chief Thomas Pratt and Associate Editor Matthew C. Gerstenberger for their useful suggestions. The authors are also thankful to I. D. Gupta for his critical discussions.
Corresponding Author: Das, R.; National Research Center for Integrated Natural Disaster Management, Avenue Vicuña Mackenna 4860, La Florida Región Metropolitana Santiago, Chile; email: ranjit244614@gmail.com
Appears in Collections:Journal Publications [EQ]

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