Learning the low frequency earthquake daily intensity on the central San
Andreas Fault
Abstract
Low frequency earthquakes (LFEs) originating below the central San
Andreas Fault are associated with slow-slip within the more ductile
portion of the crust beneath the seismogenic zone. Monitoring efforts
over 15 years recorded >1 million LFEs with
>70 per day. We apply machine learning (ML) to statistical
features describing the seismic waveforms and estimate the LFE daily
intensity. Using 4 years of independent data, the ML model produces a
0.68 correlation. The burst-like LFE behavior is reproduced and the
largest misfit occurs during the low-amplitude daily undulations. The
ability to continuously monitor LFE activity provides insight to when
geodetic measurements of slow slip are possible, without the need for
developing a computational-intensive template-matching catalog.
Similarities are found between detecting LFEs and tremors, which
provides evidence tremors are composed of LFEs. The approach reveals by
ML the rich information contained in the features of continuous seismic
waveforms.