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From relative to absolute teleseismic travel times: the absolute arrival-time recovery method (aarm)from relative to absolute teleseismic travel times

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Alistair Boyce, Ian D. Bastow, Stephane Rondenay and Robert D. Van der Hilst
From relative to absolute teleseismic travel times: the absolute arrival-time recovery method (aarm)from relative to absolute teleseismic travel times
Bulletin of the Seismological Society of America (September 2017) 107 (5): 2511-2520

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 ( approximately 10,000 picks). When compared with the available equivalent earthquake-station pairs on the International Seismological Centre (ISC) database, approximately 83% of AARM picks agree to within + or -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.


ISSN: 0037-1106
EISSN: 1943-3573
Coden: BSSAAP
Serial Title: Bulletin of the Seismological Society of America
Serial Volume: 107
Serial Issue: 5
Title: From relative to absolute teleseismic travel times: the absolute arrival-time recovery method (aarm)from relative to absolute teleseismic travel times
Pages: 2511-2520
Published: 20170925
Text Language: English
Publisher: Seismological Society of America, Berkeley, CA, United States
Accession Number: 809953-39
Document Type: Serial
Bibliographic Level: Analytic
Country of Publication: United States
Secondary Affiliation: GeoRef in Process, Copyright 2017, American Geosciences Institute. After editing and indexing, this record will be added to Georef.
Update Code: 8099
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