Duration magnitude estimate from local magnitude for moderate earthquakes in three provinces of Sulawesi

Abstract

The primary aim of this study is to estimate earthquake duration magnitude Md from local magnitude Ml for a set of seismo-tectonic events in North Sulawesi, Central Sulawesi, and West Sulawesi during 2008-2015 years. The data were collected from Webdc3, comprising datasets of magnitudes in the three regions of interest. The data were firstly used to develop corresponding local magnitudes, after which these magnitudes were analyzed to parameterize duration magnitude. Using a simple parametric equation (adopted from relevant work) directly linked Md to Ml, Md = 1.05Ml - 0.17 + c where c represented a correction factor, we found that the equation is applicable to moderate events considered with no significant difference in the calculated values whether or not c was used. For completeness, we compared the Md values in the three provinces with Mw scales provided by the Global CMT catalogue as the reference. The results show that the obtained values of Md are in good agreement with the magnitude reference of Mw within ± 0.2 units in magnitude. The results suggest that empirical relations between Md and Ml used here are appropriate for rapid and accurate magnitude determination to improve seismic hazard assessment in the three provinces.