Temporal Change and Spatial Distribution Analysis of b-value and a-value in Sumatra

Abstract

The study of seismicity is very important to be conducted in the region of interest, such as Sumatra which has high seismicity. The seismicity can be learned by using a statistical approach through the b-value and a-value parameters. The b-value describes the stress accumulation of rock while the a-value describes the seismic activity. The objective of this research is to analyse the temporal change and spatial distribution seismicity based on b-value and a-value parameters in Sumatra by using an updated earthquake catalog from 1964 to 2022. This research found that in 1965 and 1972 have b-values greater than 2 temporally. In the spatial distribution analysis, Sumatra was dominated by b-value less than 1.91. Six clusters were found to have the lowest b-value. It might indicate high seismic stress accumulation spatially in these clusters. The temporal change and spatial distribution analysis were validated by using four destructive earthquakes in Sumatra, such as Sumatra-Andaman, Nias-Simeulue, Mentawai, and Pasaman Barat earthquakes. The b-values were found to be less than 1 either temporally or spatially. The large earthquake was confirmed to have a low b-value. This indicates high seismic stress accumulation. These results can be used for further seismic hazard analysis and decision support for disaster mitigation purposes.