Estimation and Spatial Variation of Seismic b-value around the Globe

Joel, Chidithoti Sunny (2022) Estimation and Spatial Variation of Seismic b-value around the Globe. Masters thesis, Indian Institute of Science Education and Research Kolkata.

Text (MS dissertation of Chidithoti Sunny Joel (17MS209)) 17MS209_Thesis_file.pdf - Submitted Version Restricted to Repository staff only Download (8MB)

Abstract

In the current study, we refine the earthquake catalog gotten from ISC in order to get a good estimation about value of b that is seen in Gutenberg and Ritcher’s frequency and magnitude relation. Several techniques have been used to refine the earthquake catalog like the Window method to remove foreshock and aftershocks earthquake shake and a method which has been given by Weimer and weiss used in the calculation of the magnitude of completeness of observed distributions. To solve the problem of different types of magnitude(mb,mw,ms,md)in the catlog, we used the bootstrapping technique to find relation between the different magnitude types and are converted into one type.Then Maximum likely hood estimation is done to calculate the b- value. Then spatial variability is checked by taking several parts of the globe to study the observed features and estimated b – values in that area. Value of b in Japan region was seen to be 0.52 +/- 0.001 on average and its spatial variation ranged from 0.4 to 1.2 , of Philipines region it was 0.89 +/- 0.01 on average and variation of range 0.5 to 1.5 , and of El Salvador region 1.07 +/- 0.03 was the average and varied between 0.6 to 2

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