Improvements in seismic resolution and current limitations in the Global Seismographic Network

Geophysical Journal International
By: , and 



Station noise levels play a fundamental limitation in our ability to detect seismic signals. These noise levels are frequency-dependent and arise from a number of physically different drivers. At periods greater than 100 s, station noise levels are often limited by the self-noise of the instrument as well as the sensitivity of the instrument to non-seismic noise sources. Recently, station operators in the Global Seismographic Network (GSN) have deployed several Streckeisen STS-6A very broadband borehole seismometers. These sensors provide a potential replacement for the no-longer-produced Streckeisen STS-1 seismometer and the GeoTech KS-54000 borehole seismometer. Along with showing some of the initial observational improvements from installing modern very broadband seismometers at depth, we look at current limitations in the seismic resolution from Earth tide periods 100,000 s (0.01 mHz) to Nyquist at most GSN sites (0.02 s or 50 Hz). Finally, we show the potential for improved observations of continuously excited horizontal Earth hum as well as the splitting of very long-period torsional modes as a result of installing instruments at depth. Both of these observations make use of the low horizontal noise levels which are obtained by installing very broadband borehole seismometers at depth with noise levels similar to the Streckeisen STS-1.
Publication type Article
Publication Subtype Journal Article
Title Improvements in seismic resolution and current limitations in the Global Seismographic Network
Series title Geophysical Journal International
DOI 10.1093/gji/ggz473
Volume 220
Issue 1
Year Published 2019
Language English
Publisher Oxford University Press
Contributing office(s) Geologic Hazards Science Center
Description 14 p.
First page 508
Last page 521
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