Magnitude calibration for Vrancea (Romania) subcrustal earthquakes using coda waves

The coda wave amplitude is used to calibrate the moment-magnitude scale of the Vrancea (Romania) intermediate depth earthquakes. The proportionality between seismic moment and coda wave amplitude is supposed to infer a relation connecting the magnitude, the coda amplitude and the corresponding time in coda (measured from the origin time). The data set consists of waveforms recorded by the Romanian telemetered network at several seismic stations, such as Muntele Rosu (MLR), Vrancioaia (VRI), Carcaliu (CFR) and Topalu (TLB). Our results are in good agreement with the moment-magnitude scale for Vrancea subcrustal events. The independence of the two approaches allows for the verification of the local magnitude scale for the Vrancea subcrustal earthquakes. Average relations among coda amplitude, magnitude M-L and coda duration are obtained for the above-mentioned stations.