On the Analysis of Wind-Induced Noise in Seismological Recordings
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Atmospheric processes, ranging from microscale turbulence to severe storms on the synoptic scale, impact the continuous ground motion of the earth and have the potential to induce strong broad-band noise in seismological recordings. We designed a target-oriented experiment to quantify the influence of wind on ground motion velocity in the Dead Sea valley. For the period from March 2014 to February 2015, a seismological array, consisting of 15 three-component short-period and broad-band stations, was operated near Madaba, Jordan, complemented by one meteorological tower providing synchronized, continuous three-component measurements of wind speed. Results reveal a pronounced, predominantly linear increase of the logarithmic power of ground motion velocity with rising mean horizontal wind speed at all recording stations. Measurements in rough, mountainous terrain further identify a strong dependency of wind-induced noise on surface characteristics, such as topography and, therefore, demonstrate the necessity to consider wind direction as well. To assess the noise level of seismological recordings with respect to a dynamically changing wind field, we develop a methodology to account for the dependency of power spectral density of ground motion velocity on wind speed and wind direction for long, statistically significant periods. We further introduce the quantitative measure of the ground motion susceptibility to estimate the vulnerability of seismological recordings to the presence of wind.
KeywordsSeismology noise wind speed dead sea microseisms spectral analysis topography
This study was part of the DESERVE project and as such funded by the Helmholtz Association (HGF). It was realized at the Institute of Meteorology (IMK) in close collaboration and with major support of the Geophysical Institute (GPI) at the Karlsruhe Institute of Technology (KIT). We want to thank Prof. Dr. Kottmeier for making the project possible and Werner Scherer for his expertise and commitment in the field work. In Jordan, we collaborated with the Ministry of Energy and Mineral Resources (MEMR) who supported this project beyond all expectations. Seismometers and data loggers were provided by the Geophysical Instrument Pool (GIPP) at the GeoForschunsZentrum (GFZ) Potsdam for all array stations. Waveforms from recording station GHAJ were provided by the GEOFON datacenter at GFZ (Hanka and Kind 1994).
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