Broadband Seismic Background Noise at Temporary Seismic Stations Observed on a Regional Scale in the Southwestern United States

Wilson, David C.; Leon, Joseph J.; Aster, R. C.; Ni, James; Schlue, J. W.; Grand, S. P.; Semken, S.; Baldridge, S.; Gao, Wei

doi:10.1785/0120010234

Cited by 82 publications

(58 citation statements)

References 14 publications

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“…The difference remains small all along the spectra for the vertical component and becomes large for LPs recorded at horizontal components (more than 15 dB). The increased amplitudes of LP horizontal noise at temporary sites is a well-known phenomenon related to the poorer insulation from atmospheric variations (Wilson et al, 2002;Díaz et al, 2010). Ⓔ This phenomenon can also be seen in Figure S1, available in the electronic supplement to this article, which shows noise amplitudes for different instruments in the east-west direction.…”

Section: Characterization Of Background Noisementioning

confidence: 71%

Ambient Noise Recorded by a Dense Broadband Seismic Deployment in Western Iberia

Custódio¹,

Dias²,

Caldeira³

et al. 2014

Bulletin of the Seismological Society of America

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The West Iberia Lithosphere and Asthenosphere Structure (WILAS) project densely covered Portugal with broadband seismic stations for 2 yrs. Here we provide an overview of the deployment, and we characterize the network ambient noise and its sources. After explaining quality control, which includes the assessment of sensor orientation, we characterize the background noise in the short-period (SP), microseismic, and long-period (LP) bands. We observe daily variations of SP noise associated with anthropogenic activity. Temporary and permanent stations present very similar noise levels at all periods, except at horizontal LPs, where temporary stations record higher noise levels. We find that median noise levels are extremely homogeneous across the network in the microseismic band (3-20 s) but vary widely outside this range. The amplitudes of microseismic noise display a strong seasonal variation. The seasonality is dominated by very-long-period double-frequency microseisms (8 s), probably associated with winter storms. Stacks of ambient noise amplitudes show that some microseismic noise peaks are visible across the whole ground-motion spectrum, from 0.3 to 100 s. Periods of increased microseismic amplitudes generally correlate with ocean conditions offshore of Portugal. Some seismic records display an interesting 12 hr cycle of LP (100-s) noise, which might be related to atmospheric tides. Finally, we use plots of power spectral density versus time to monitor changes in LP instrumental response. The method allows the identification of the exact times at which LP response changes occur, which is required to improve the understanding of this instrumental artifact and to eventually correct data.

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Section: Characterization Of Background Noisementioning

confidence: 71%

Ambient Noise Recorded by a Dense Broadband Seismic Deployment in Western Iberia

Custódio¹,

Dias²,

Caldeira³

et al. 2014

Bulletin of the Seismological Society of America

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“…Wilson et al (2002) generated noise acceleration power spectral density estimates between 0.01 and ~8.5 Hz from measurements with seismometers at stations along a 951-km network transecting Utah, New Mexico, and Texas. The seismometers were surface mounted in dirt-covered vaults.…”

Section: Geographic Variationmentioning

confidence: 99%

“…Wilson et al (2002) compared median midday and midnight noise levels measured at seismic stations along a ~951-km linear network extending between Utah and Texas. At low frequencies (0.01-0.06 Hz), midday noise levels were ~2 dB higher (vertical components) and more than 7 dB higher (horizontal components).…”

Section: Seasonal and Diurnal Variationmentioning

confidence: 99%

Overview of Seismic Noise and it's Relevance to Personnel Detection

Peck¹

2008

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Seismic noise refers to the ambient ground motion within which signals of interest are to be detected. Four categories of seismic noise identified by source-road (vehicle), train, wind, and ocean microseisms-are reviewed. Examples are given of the variation in seismic noise by geographic location and by season and time of day, and of a technique to characterize seismic site effects from local seismic noise. Noise impact on seismic detection of personnel is discussed, and ground motion induced by a walking person is compared with noise at a rural site when cultural activity is minimal and when a moving vehicle is present.

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“…McNamara and Buland (2004) have carried out noise studies for continental stations of the United States and found that very few stations reach the new low noise level (NLNM) proposed by Peterson (1993) and also observed strong geographical variations for periods less than 1 s. Further it was discovered by them that the stations surrounded by urban areas show high noise levels. Wilson (2002) observed that high frequency (0.3-8.5 Hz) median noise levels are controlled by their proximity to local cultural noise sources. The lowest noise levels are observed at culturally remote sites.…”

Section: Introductionmentioning

confidence: 99%

“…The SBN study by Vila (1998) in the eastern Pyrenees shows that the noise level of horizontal components is of the same order as the vertical, showing good site conditions as well as good coupling of the sensors. Wilson (2002) carried out this type of study for the temporary seismic stations in the southwestern United States.…”

Section: Introductionmentioning

confidence: 99%

Ambient noise levels in Gujarat State (India) seismic network

Kumar

Chopra

Choudhury

et al. 2012

Geomatics, Natural Hazards and Risk

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The Gujarat state seismic network (GSNet), comprising of 50 broadband seismograph (BBS) stations and 40 strong motion accelerographs (SMAs), has been operated and maintained by the Institute of Seismological Research (ISR) since 2006. Nineteen permanent BBS stations are connected through VSAT and the rest are kept in an offline mode. The local geology beneath seismic stations varies from Mesozoic to Quaternary formations. The seismic background noise (SBN) at these stations was calculated and found that it varies widely as a function of period, time and geographic location. We have studied the SBN variation along these three parameters for 14 online BBS stations of the GSNet. It was found that the stations located on the Deccan trap and Mesozoic formations are good sites with low SBN while stations on Quaternary, Tertiary and soft soil are noisy. The comparison between day and night noise spectra shows that SBN increases during the daytime at most of the stations. Three typical noisy peaks at three different periods were recorded at all of the stations, which is a global phenomenon. The results of this study will be helpful in selecting sites for future earthquake observations.

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Broadband Seismic Background Noise at Temporary Seismic Stations Observed on a Regional Scale in the Southwestern United States

Cited by 82 publications

References 14 publications

Ambient Noise Recorded by a Dense Broadband Seismic Deployment in Western Iberia

Ambient Noise Recorded by a Dense Broadband Seismic Deployment in Western Iberia

Overview of Seismic Noise and it's Relevance to Personnel Detection

Ambient noise levels in Gujarat State (India) seismic network

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