From Relative to Absolute Teleseismic Travel Times: The Absolute Arrival‐Time Recovery Method (AARM)
File(s)Boyce_et_al_BSSA_2017.pdf (1.08 MB)
Published version
Author(s)
Boyce, A
Bastow, ID
Rondenay, S
Van der Hilst, RD
Type
Journal Article
Abstract
Dense, short‐term deployments of seismograph networks are frequently used to study upper‐mantle structure. However, recordings of variably emergent teleseismic waveforms are often of lower signal‐to‐noise ratio (SNR) than those recorded at permanent observatory sites. Therefore, waveform coherency across a network is frequently utilized to calculate relative arrival times between recorded traces, but these measurements cannot easily be combined or reported directly to global absolute arrival‐time databases. These datasets are thus a valuable but untapped resource with which to fill spatial gaps in global absolute‐wavespeed tomographic models.
We developed an absolute arrival‐time recovery method (AARM) to retrieve absolute time picks from relative‐arrival‐time datasets, working synchronously with filtered and unfiltered data. We also include a relative estimate of uncertainty for potential use in data weighting during subsequent tomographic inversion. Filtered waveforms are first aligned via multichannel cross correlation. These time shifts are applied to unfiltered waveforms to generate a phase‐weighted stack. Cross correlation with the primary stack or the SNR of each trace is used to weight a second‐higher SNR stack. The first arrival on the final stack is picked manually to recover absolute arrival times for the aligned waveforms.
We test AARM on a recently published dataset from southeast Canada ( ∼10,000∼10,000 picks). When compared with the available equivalent earthquake–station pairs on the International Seismological Centre (ISC) database, ∼83%∼83% of AARM picks agree to within ±0.5 s±0.5 s . Tests using synthetic P‐wave data indicate that AARM produces absolute arrival‐time picks to accuracies of better than 0.25 s, akin to uncertainties in ISC bulletins.
We developed an absolute arrival‐time recovery method (AARM) to retrieve absolute time picks from relative‐arrival‐time datasets, working synchronously with filtered and unfiltered data. We also include a relative estimate of uncertainty for potential use in data weighting during subsequent tomographic inversion. Filtered waveforms are first aligned via multichannel cross correlation. These time shifts are applied to unfiltered waveforms to generate a phase‐weighted stack. Cross correlation with the primary stack or the SNR of each trace is used to weight a second‐higher SNR stack. The first arrival on the final stack is picked manually to recover absolute arrival times for the aligned waveforms.
We test AARM on a recently published dataset from southeast Canada ( ∼10,000∼10,000 picks). When compared with the available equivalent earthquake–station pairs on the International Seismological Centre (ISC) database, ∼83%∼83% of AARM picks agree to within ±0.5 s±0.5 s . Tests using synthetic P‐wave data indicate that AARM produces absolute arrival‐time picks to accuracies of better than 0.25 s, akin to uncertainties in ISC bulletins.
Date Issued
2017-09-28
Date Acceptance
2017-05-25
Citation
Bulletin of the Seismological Society of America, 2017, 107 (5), pp.2511-2520
ISSN
0037-1106
Publisher
Seismological Society of America
Start Page
2511
End Page
2520
Journal / Book Title
Bulletin of the Seismological Society of America
Volume
107
Issue
5
Copyright Statement
This copy is for distribution only by
the authors of the article and their institutions
in accordance with the Open Access Policy of the
Seismological Society of America.
the authors of the article and their institutions
in accordance with the Open Access Policy of the
Seismological Society of America.
Sponsor
The Leverhulme Trust
Natural Environment Research Council
Grant Number
RPG-2013-332
NE/L002515/1
Subjects
0404 Geophysics
0905 Civil Engineering
Geochemistry & Geophysics
Publication Status
Published
Date Publish Online
2017-09-28