Homogeneous earthquake catalogue for Northeast region of India using robust statistical approaches

Auchitya Kumar Pandey,Prasanta Chingtham,P N S Roy

doi:10.1080/19475705.2017.1345794

Abstract

ABSTRACTRegular seismic hazard assessment requires essentially an updated and refined homogenous earthquake catalogue for the study region. Here, we have compiled the earthquake data for Northeast region of India in a chronological order from International Seismological Centre and Global Centroid Moment Tensor databases during the period 1 January 1900 to 31 April 2016. For this purpose, the regression techniques such as least square (SR), inverse least square (ISR), orthogonal (OR) and generalized orthogonal (GOR) which is the best one, out of that are employed for converting different types of magnitude scales, such as surface-wave magnitude (MS), body-wave magnitude (mb) and local magnitude (ML) into a single homogenized moment magnitude, MW. The homogenized catalogue is then treated with ‘runs test’ to estimate p-value of 0.8421 which suggest no spurious reporting on the catalogue. The prepared catalogue has also been declustered using standard procedure. Furthermore, the magnitude of completeness for space and time with 90% confidence level has been achieved. The seismicity parameters, namely magnitude of completeness MC, a-value and b-value are found to be 4.6, 7.50 and 0.95(±0.023), respectively. The observed low b-value implies that the study region is tectonically very active with the presence of asperity.

Highlights

The Northeast region of India is seismically very active and its seismicity is primarily attributed to the Indian-Asian plates collision in the north and Indian-Sunda plates interaction in the Indo-Burmese arc in the east (Bilham and England 2001; Kayal et al 2012)
A homogenized earthquake catalogue pertaining to Northeast India and its adjoining region has been compiled by using different regression techniques during the time period 1 January 1900 to 31 April 2016
The associated errors with the variables are found to be high in the regression equation for converting magnitude scale (MS) into MW and MS-MW regression relation is not employed during the homogenization process (Equations (8) and (9))

Summary

Introduction

The Northeast region of India is seismically very active and its seismicity is primarily attributed to the Indian-Asian plates collision in the north and Indian-Sunda plates interaction in the Indo-Burmese arc in the east (Bilham and England 2001; Kayal et al 2012). The mechanical deformations due to these interactions resulted in the formation of the most seismically active Himalayan thrust faults in the north, Arakan-Yoma, Naga Hills and Tripura folded belt in the east and the uplift of Shillong plateau in the zone-III (Thingbaijam et al 2008). Bhatia et al (1999) estimated the peak ground acceleration (PGA) which was found within the range, 0.35–0.45g for the Global Seismic Hazard Assessment Programme.

January 2016

Results and discussions

Conclusions