Ambient noise levels and detection threshold in Norway
Andrea Demuth1, Lars Ottemöller1, Henk Keers1
1Department of Earth Science, University of Bergen, Allégaten 41, N-5007 Bergen, Norway.
Journal of Seismology
|February 14, 2017
Summary
Ambient seismic noise levels in Norway were analyzed, revealing significant correlations with oceanic wave heights. Higher noise levels decrease earthquake detection sensitivity, impacting seismic network performance.
Area of Science:
- Geophysics
- Seismology
- Environmental Science
Background:
- Ambient seismic noise quantification is crucial for assessing seismic station and network performance.
- Norway's seismic noise is influenced by oceanic microseism peaks, necessitating localized noise modeling.
Purpose of the Study:
- To evaluate ambient seismic noise levels and variations across Norway.
- To develop a local noise model for Norway, considering geographical and temporal factors.
- To investigate the relationship between oceanic weather conditions and seismic noise.
Main Methods:
- Analysis of seismic data from the Norwegian National Seismic Network and temporary deployments (2013).
- Correlation analysis between seismic noise levels and offshore wave heights at various distances.
- Assessment of the impact of high-frequency noise on earthquake detectability.
Main Results:
- Low-frequency seismic noise (0.125-0.25 Hz) correlates with wave heights up to 900 km offshore.
- High (2-10 Hz) and intermediate (0.5-5 Hz) frequency noise correlate with wave heights up to 450 km offshore.
- A 10 dB increase in high-frequency noise reduces earthquake detectability by 0.5 magnitude units.
Conclusions:
- Oceanic weather significantly influences seismic noise in Norway, with varying spatial correlations based on frequency.
- Geographical location impacts noise levels, with southern Norway exhibiting lower low-frequency noise.
- Seismic noise variations must be considered for accurate earthquake detection mapping and network performance evaluation.
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