Rapid estimation of earthquake magnitude from the arrival time of the peak high‐frequency amplitude

Bulletin of the Seismological Society of America
By: , and 

Links

Abstract

We propose a simple approach to measure earthquake magnitude M using the time difference (Top) between the body‐wave onset and the arrival time of the peak high‐frequency amplitude in an accelerogram. Measured in this manner, we find that Mw is proportional to 2logTop for earthquakes 5≤Mw≤7, which is the theoretical proportionality if Top is proportional to source dimension and stress drop is scale invariant. Using high‐frequency (>2  Hz) data, the root mean square (rms) residual between Mw and MTop(M estimated from Top) is approximately 0.5 magnitude units. The rms residuals of the high‐frequency data in passbands between 2 and 16 Hz are uniformly smaller than those obtained from the lower‐frequency data. Top depends weakly on epicentral distance, and this dependence can be ignored for distances <200  km. Retrospective application of this algorithm to the 2011 Tohoku earthquake produces a final magnitude estimate of M 9.0 at 120 s after the origin time. We conclude that Top of high‐frequency (>2  Hz) accelerograms has value in the context of earthquake early warning for extremely large events.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Rapid estimation of earthquake magnitude from the arrival time of the peak high‐frequency amplitude
Series title Bulletin of the Seismological Society of America
DOI 10.1785/0120150108
Volume 106
Issue 1
Year Published 2016
Language English
Publisher Seismological Society of America
Publisher location Stanford, CA
Contributing office(s) Earthquake Science Center
First page 232
Last page 241
Online Only (Y/N) N
Additional Online Files (Y/N) N