Journal of Environmental Biology

Temporal variation of b-value and seismicity in the Indo-Burma Region: A precursor to large earthquake

L. Tlau¹, Z. Ralte¹*, S. Sailo², Lalhmingsangi³, H. Lawmkima², V. Vanthangliana², C. Lalremruatfela², H. Malsawmtluangkima² and J. Lalnunmawia³     

¹Department of Geophysics, Pachhunga University College, Aizawl-796 001, India

²Department of Geology, Pachhunga University College, Aizawl-796 001, India

³Department of Geology, Mizoram University, Aizawl-796 004, India

Received: 13 June 2025                   Revised: 20 August 2025                   Accepted: 05 September 2025

*Corresponding Author Email : zosangaralte9@gmail.com                  *ORCiD: https://orcid.org/0000-0002-9703-1369

Abstract

Aim: To determine seismicity parameters such as a-value, b-value, and Mc (magnitude of completeness) for different time periods from 1965 to 2022 in the Indo-Burmese region. This study also aims to analyze temporal variations and their implications for seismic hazard assessment.

Methodology: Seismic catalog data were obtained from the International Seismological Centre (ISC) and the United States Geological Survey (USGS) for the period 1965-2022. The data were homogenized into moment magnitude (Mw) and segmented into intervals of at least five years with a minimum of 50 seismic events per interval. Declustering was performed with Gardner and Knopoff algorithm. Seismic parameters were determined by the Gutenberg-Richter relation and maximum curvature method.

Results: The b-values varied approximately 0.75 to 1.64 over different time periods, with an average range of 0.9 to 1.2. Mc exhibited a decreasing trend over time, stabilizing at 4.1. These results indicate improved data quality and suggest changes in the stress regime and tectonic activity in the Indo-Burmese region over time. The lowest b value was observed between 2020 to 2022.

Interpretation: Temporal variations in seismicity parameters reflect the evolving tectonic processes and stress accumulation in the region. The observed decrease in Mc over time suggests improvements in seismic data recording. Variations in b-value indicate periods of stress accumulation and release, highlighting the importance of continued seismic monitoring for hazard assessment. This study suggests low b value from 2005 to 2022 in the region due to the buildup of stress and a potential large earthquake in the future.

Key words: Earthquakes, Hazard assessment, Indo-Burmese region, Seismicity

Copyright © 2026 Triveni Enterprises. All rights reserved. No part of the Journal can be reproduced in any form without prior permission. Responsibility regarding the authenticity of the data, and the acceptability of the conclusions enforced or derived, rest completely with the author(s).