T phase observations in global seismogram stacks

TitleT phase observations in global seismogram stacks
Publication TypeJournal Article
Year of Publication2015
AuthorsBuehler J.S, Shearer PM
JournalGeophysical Research Letters
Date Published2015/08
Type of ArticleArticle
ISBN Number0094-8276
Accession NumberWOS:000363410800010
Keywordscalifornia; land; propagation; waves

The T phase, conversion of acoustic to seismic energy, is typically observed as a high-frequency wave train at hydrophones or coastal seismic stations. Here we show that the T phase can be observed in broadband waveform stacks of similar to 5200 earthquakes recorded by the Global Seismic Network. To enhance the phase arrivals in stacks, we apply short-time window average over long-time window average filtering to individual traces before stacking. Although the T phase arrival is visible in stacks from seismograms filtered at 0.5-5 Hz, it appears much stronger at higher frequencies (2-8 Hz) and is further enhanced by only stacking seismograms from oceanic paths. Stacking only subsets of the data depending on continental path lengths on the receiver side shows that the T phase can be observed at stations up to 4 degrees inland from the coast, and changes in the T phase arrival time correspond to reasonable crustal velocities.

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