Characterizing local variability in long‐period horizontal tilt noise

Seismological Research Letters
By: , and 



Horizontal seismic data are dominated by atmospherically induced tilt noise at long periods (i.e., 30 s and greater). Tilt noise limits our ability to use horizontal data for sensitive seismological studies such as observing free earth modes. To better understand the local spatial variability of long‐period horizontal noise, we observe horizontal noise during quiet time periods in the Albuquerque Seismological Laboratory (ASL) underground vault using four small‐aperture array configurations. Each array comprises eight Streckeisen STS‐2 broadband seismometers. We analyze the spectral content of the data using power spectral density and magnitude‐squared coherence (γ2‐coherence). Our results show a high degree of spatial variability and frequency dependence in the long‐period horizontal wavefield. The variable nature of long‐period horizontal noise in the ASL vault suggests that it might be highly local in nature and not easily characterized by simple physical models when overall noise levels are low, making it difficult to identify locations in the vault with lower horizontal noise. This variability could be limiting our ability to apply coherence analysis for estimating horizontal sensor self‐noise and could also complicate various indirect methods for removing long‐period horizontal noise (e.g., collocated rotational sensor or microbarograph).

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Characterizing local variability in long‐period horizontal tilt noise
Series title Seismological Research Letters
DOI 10.1785/0220160193
Volume 88
Issue 3
Year Published 2017
Language English
Publisher Seismological Society of America
Contributing office(s) Geologic Hazards Science Center
Description 9 p.
First page 822
Last page 830
Country United States
State New Mexico
City Albuquerque