Automatic detection and rapid determination of earthquake magnitude by wavelet multiscale analysis of the primary arrival

Frederik J Simons¹, Ben D. E. Dando¹, and Richard M. Allen²

1 Earth Sciences Department
University College London
London, WC1E 6BT, UK

2 Department of Earth and Planetary Science
University of California Berkeley
Berkeley, CA 94270, USA

Abstract

Earthquake early warning systems save lives. It is of great importance that networked systems of seismometers be equipped with reliable tools to make rapid determinations of earthquake magnitude. We have designed an algorithm that detects as well as analyzes the incoming first arrival by way of a discrete wavelet transform. The speed with which the determinations can be performed, the detection hit rates, and the correlation of the wavelet observables to the earthquake magnitude suggest that our procedure is the most effective to date and holds enormous potential for its implementation on fully automated systems.

Figures

1. Figure 01 Map of the study area, earthquakes, and stations
   
2. Figure 02 Two seismograms and zooms on the P wave
   
3. Figure 03 Spectrograms and predominant frequency of both seismograms
   
4. Figure 04 Scalograms of both seismograms
   
5. Figure 05 The correlation between earthquake magnitude and wavelet coefficient amplitude
   
6. Figure 06 Error in magnitude prediction based on thresholded coefficients at scale 5
   
7. Figure X1 Error in magnitude prediction based on thresholded coefficients at different scales (not included in paper)