Noise reduction in long‐period seismograms by way of array summing

Bulletin of the Seismological Society of America
By: , and 

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Abstract

Long‐period (>100  s period) seismic data can often be dominated by instrumental noise as well as local site noise. When multiple collocated sensors are installed at a single site, it is possible to improve the overall station noise levels by applying stacking methods to their traces. We look at the noise reduction in long‐period seismic data by applying the time–frequency phase‐weighted stacking method of Schimmel and Gallart (2007) as well as the phase‐weighted stacking (PWS) method of Schimmel and Paulssen (1997) to four collocated broadband sensors installed in the quiet Albuquerque Seismological Laboratory underground vault. We show that such stacking methods can improve vertical noise levels by as much as 10 dB over the mean background noise levels at 400 s period, suggesting that greater improvements could be achieved with an array involving multiple sensors. We also apply this method to reduce local incoherent noise on horizontal seismic records of the 2 March 2016 Mw 7.8 Sumatra earthquake, where the incoherent noise levels at very long periods are similar in amplitude to the earthquake signal. To maximize the coherency, we apply the PWS method to horizontal data where relative azimuths between collocated sensors are estimated and compared with a simpler linear stack with no azimuthal rotation. Such methods could help reduce noise levels at various seismic stations where multiple high‐quality sensors have been deployed. Such small arrays may also provide a solution to improving long‐period noise levels at Global Seismographic Network stations.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Noise reduction in long‐period seismograms by way of array summing
Series title Bulletin of the Seismological Society of America
DOI 10.1785/0120160129
Volume 106
Issue 5
Year Published 2016
Language English
Publisher Seismological Society of America
Publisher location Stanford, CA
Contributing office(s) Geologic Hazards Science Center
Description 7 p.
First page 1991
Last page 1997
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