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

Abstract

Regular 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 (M S ), body-wave magnitude (m b ) and local magnitude (M L ) into a single homogenized moment magnitude, M W . 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 M C , 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.

Seismicity Parameters Analysis In Space-Time Distribution For Northeast India.

“…This study region is a high seismically active region that encompasses the latitude and longitude as 21°N-30°N and 81°E-98°E. Northeast India falls into the highest seismic active zone, i.e., Zone V, according to the seismic zonation map of India (BIS, 2002; Pandey et al, 2017). The seismicity of Northeast India is signi cantly very high because of low to high magnitude earthquakes that occurred, causing loss of human life and destroyed buildings (Yadav et al, 2009).…”

“…The occurrence of moderate to large magnitude earthquakes makes this study region as high seismically active of the Indian sub-continent. In the past 120 years, several low to high magnitude earthquakes (M W ≥ 3.0 to (Pandey et al, 2017). The Indian Plate and the Eurasian Plate convergence and continentcontinent collision in the north direction and subduction of the Indian plate beneath the Burmese plate in the east direction is the prime reason for the occurrence of low to high magnitude earthquakes (Bilham and England, 2001;Angelier and Baruah, 2009;Kayal et al, 2010Kayal et al, , 2012.…”

GIS-Based Mapping of Seismic Parameters for the Pyrenees

“…There are different values to establish these windows. In this research, the proposal by Uhrhammer [83] has been chosen as it is a conservative solution and widely used [29,81,82,84,85]. After determining the M c , regarding the b-value calculation, the cut-off magnitude (M co ≥ M c ) for this work has been set as 2.0 (M2), to have a margin and, besides, consider a standard value.…”

“…The importance of earthquake catalogs in seismic studies is crucial [8,10,11,[29][30][31]. Due to the different content of seismic information for both historical and instrumental epochs, a critical point in the catalog analysis is to generate a reliable, updated, extensive, and homogeneous catalog for the studied region to make the results comparable.…”

A unified moment magnitude earthquake catalog for Northeast India

“…In regards to the homogenization of an earthquake catalog for Northeast India using regression relationships, several authors have worked on empirical relationships between different magnitudes and moment magnitude scale (Thingbaijam et al 2008, Yadav et al 2009Das et al 2012aDas et al , 2012bAnbazhagan and Balakumar 2019;Nath et al 2017;Pandey et al 2017). Thingbaijam et al (2008) derived GOR for the conversion of body and surface wave magnitudes into moment magnitude, finding significant dispersion in the conversion of m b,ISC into M w .…”