A comparison of methods to estimate seismic phase delays--Numerical examples for coda wave interferometry

Geophysical Journal International
By: , and 

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Abstract

Time-shift estimation between arrivals in two seismic traces before and after a velocity perturbation is a crucial step in many seismic methods. The accuracy of the estimated velocity perturbation location and amplitude depend on this time shift. Windowed cross correlation and trace stretching are two techniques commonly used to estimate local time shifts in seismic signals. In the work presented here, we implement Dynamic Time Warping (DTW) to estimate the warping function – a vector of local time shifts that globally minimizes the misfit between two seismic traces. We illustrate the differences of all three methods compared to one another using acoustic numerical experiments. We show that DTW is comparable to or better than the other two methods when the velocity perturbation is homogeneous and the signal-to-noise ratio is high. When the signal-to-noise ratio is low, we find that DTW and windowed cross correlation are more accurate than the stretching method. Finally, we show that the DTW algorithm has better time resolution when identifying small differences in the seismic traces for a model with an isolated velocity perturbation. These results impact current methods that utilize not only time shifts between (multiply) scattered waves, but also amplitude and decoherence measurements. DTW is a new tool that may find new applications in seismology and other geophysical methods (e.g., as a waveform inversion misfit function).

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title A comparison of methods to estimate seismic phase delays--Numerical examples for coda wave interferometry
Series title Geophysical Journal International
DOI 10.1093/gji/ggv138
Volume 202
Issue 1
Year Published 2015
Language English
Publisher Oxford University Press on behalf of The Royal Astronomical Society
Contributing office(s) Volcano Science Center
Description 13 p.
First page 347
Last page 360