Comment on “Earthquake magnitude estimation from peak amplitudes of very early seismic signals on strong motion records” by Aldo Zollo, Maria Lancieri, and Stefan Nielsen

Abstract

] An early warning system should determine the loca-tion and magnitude of an earthquake as rapidly as possiblein order to broadcast an alarm to regions that will undergosevere ground shaking. It was recently claimed by Zollo etal. [2006] that earthquake size could be determined fromonly the first 2-seconds of P- or S-wave strong-motion data;this represents a fraction of the rupture time for larger M >7 events. Using this relatively short amount of data, themethod of analysis was to find the peak ground displace-ment (PGD), which was reported to scale with earthquakemagnitude; such rapid information would play an importantand much needed role in an earthquake early warning(EEW) system. Here we perform a similar analysis onstrong-motion data from the KiK-net and K-NET arrays inJapan and find no compelling evidence that the peak grounddisplacement during the first couple of seconds of P-wave isrelated to the eventual size of a large earthquake.[