Earthquake Distribution in Northeast India from 1961-2010

Abong A. A., George A. M., Awhuwhe E. A.

Abstract: This study investigated earthquake distribution in Northeast India from 1961 to 2010 with body wave magnitude, Mb 2.9. Measure of central tendencies and spread, bar chart, pie chart, scatter plot were the statistical tools used. The data were obtained from International Seismological Centre (ISC) On-line Bulletin, United Kingdom from 1st January 1961 to 31st December, 2010 (50years). Frequency-Magnitude Relationship was employed and the constants were calculated to be a=6.80 and b=0.93. The findings of the study revealed that Northeast India is characterized majorly by minor and light earthquakes with low spatial spread. The rate of seismic activity for magnitude range 2.0-2.9, 3.0-3.9 is regular while for 4.0-4.9, 5.0-5.9 and 6.0-6.9 are irregular or fluctuating. It therefore implies that these trends may continue in future, but the probability of occurrence of great earthquake is low. However, one has to take caution because tectonic activities of deformation and uncertainties of occurrence of earthquake are not well understood. Hence, the possibility of occurrence of large earthquakes as a result of uncertainties associated with earthquake predictions, especially in intraplate and plate-boundary regions.

Keywords: Frequency-Magnitude relationship, seismicity, seismotectonic, epicentre, intraplate region, plate-boundary region.