We report on a 4-year experiment of routine automatic determination of seismic moments using the mantle magnitude Mm. We have developed a system performing automatic detection and location of distant earthquakes, on the basis of three-component broadband records at a single seismic station. This system, which has been operational since 1987 at Papeete, Tahiti, computes Mm from the spectral amplitude of the mantle Rayleigh waves. Based on a dataset of 474 earthquakes, we show that Mm provides a excellent estimate of the quantity log10M0 - 20, where M0 is the seismic moment in dyn-cm, as published subsequently by the Harvard and USGS groups. The average residual is 0.07 units of magnitude, and the standard deviation 0.22 units. This method, which necessitates minimal hardware, has powerful applications in the field of tsunami warning.
ASJC Scopus subject areas
- Earth-Surface Processes