Empirical relationships of earthquake magnitudes for local regions considering the active tectonic boundary areas
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Abstract
Local magnitude ML and surface wave magnitude MS are two widely used scales of earthquake magnitude, which usually need to be converted to each other using empirical equations. Due to a limit of data, and ignorance the difference in geological conditions, empirical equations based on historical earthquakes suffer from conversion errors in practice. Based on the historical earthquake data of 12 621 records with both ML and MS recorded in the past four decades, this paper derived the empirical conversion equations between ML and MS by regression analysis. Furthermore, empirical conversion equations were derived from the partitioned data for the 27 regions classified according to the secondary active tectonic boundary areas. The results show that the correlation between MS and ML is more significant after the magnitude data are partitioned, and the magnitudes that were converted with consideration of active tectonic boundaries showed lower conversion error.
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