Early Warning Magnitude MEW

Last Update by Colombelli S. on May 23, 2012

The figures show the average values of Peak Displacement (Pd) and Predominant Period (Tauc) as a function of the P-wave time window. Error bars are computed as the standard deviation associated to each value; the grey number close to each point represents the number of stations used for each considered time window. For both plots, the corresponding magnitude scale is also represented. An empirical attenuation law between Peak Displacement, hypocentral distance and magnitude and the Tauc vs. M relationship of Zollo et al. (2010) have been used to estimate magnitude from the early P-wave amplitude and the predominant period, respectively. To avoid the S-wave contamination we computed the theoretical S-wave arrival times and excluded stations for which the estimated time occurs within the P-wave time window. We used a S-wave velocity of 3.5 km/s for the top plot and of 4.7 km/s for the bottom plot.