The Relationship of MW-ML Conversion for the Earthquakes of the Marmara Region

Earthquake magnitude is one of the most important parameters which is a measure directly related to the energy released characterizing an earthquake. Several magnitude scales (local magnitude, (ML), body-wave magnitude, (mb), surface-wave magnitude, (MS), moment magnitude, (Mw)) are used for defining the size of an earthquake. ML, mb and MS being based on amplitude measurements of specific types of seismic waves, in specified frequency ranges, sometimes recorded with a specific instrument. Because of different waves have been using to estimate the earthquake’s magnitude at different distances, they may significantly differ between each other. However, Mw is based on seismic moment, which is a physical quantity proportional to the energy released by the seismic source, hence it does not saturate even for very large earthquakes, so it has better representation for earthquake magnitude. In this study, we calculated seismic moment values and Mw magnitudes for 70 earthquakes (3.4 < M < 5.4) by using P-wave spectrum. ML magnitudes were taken from Kandilli Observatory and Earthquake Research Institute (KOERI) catalogues. Then we obtained an empirical relationship as Mw=0.7018ML+1.1715 by using regression analysis between Mw and ML