Real time monitoring of moment magnitude by waveform inversion

Abstract

An instantaneous measure of the moment magnitude (M w) of an ongoing earthquake is estimated from the moment rate function (MRF) determined in real-time from available seismic data using waveform inversion. Integration of the MRF gives the moment function from which an instantaneous M w is derived. By repeating the inversion procedure at regular intervals while seismic data are coming in we can monitor the evolution of seismic moment and M w with time. The final size and duration of a strong earthquake can be obtained within 12 to 15 minutes after the origin time. We show examples of M w monitoring for three large earthquakes at regional distances. The estimated M w is only weakly sensitive to changes in the assumed source parameters. Depending on the availability of seismic stations close to the epicenter, a rapid estimation of the M w as a prerequisite for the assessment of earthquake damage potential appears to be feasible.Copyright 2012 by the American Geophysical Union.