scholarly journals Observations and modeling of seismic background noise

1993 ◽  
Author(s):  
Jon R. Peterson
Keyword(s):  
Background Noise ◽  
Seismic Background

Retrieval of reflections from seismic background-noise measurements

2007 ◽  
Vol 34 (4) ◽  
Author(s):  
Deyan Draganov ◽  
Kees Wapenaar ◽  
Wim Mulder ◽  
Johannes Singer ◽  
Arie Verdel
Keyword(s):  
Background Noise ◽  
Noise Measurements ◽  
Seismic Background

High-frequency analysis of seismic background noise as a function of wind speed and shallow depth

1996 ◽  
Vol 86 (5) ◽  
pp. 1507-1515 ◽  
Author(s):  
Mitchell M. Withers ◽  
Richard C. Aster ◽  
Christopher J. Young ◽  
Eric P. Chael
Keyword(s):  
Wind Speed ◽  
High Frequency ◽  
Background Noise ◽  
Signal To Noise Ratio ◽  
Shallow Depth ◽  
High Frequency Signal ◽  
Wind Speeds ◽  
Noise Characteristics ◽  
Cultural Noise ◽  
Seismic Background

Abstract We used a deep (1500 m) cased borehole near the town of Datil in west-central New Mexico to study high-frequency (>1 Hz) seismic noise characteristics. The remote site had very low levels of cultural noise, but strong winds (winter and spring) made the site an excellent candidate to study the effects of wind noise on seismograms. Along with a three-component set of surface sensors (Teledyne Geotech GS-13), a vertical borehole seismometer (GS-28) was deployed at a variety of depths (5, 43, and 85 m) to investigate signal and noise variations. Wind speed was measured with an anemometer. Event-triggered and time-triggered data streams were recorded on a RefTek 72-02 data acquisition system located at the site. Our data show little cultural noise and a strong correlation between wind speed and seismic background noise. The minimum wind speed at which the seismic background noise appears to be influenced varies with depth: 3 m/sec at the surface, 3.5 m/sec at 43 m in depth, and 4 m/sec at 85 m in depth. For wind speed below 3 to 4 m/sec, we observe omni-directional background noise that is coherent at frequencies below 15 Hz. This coherence is destroyed when wind speeds exceed 3 to 4 m/sec. We use a test event (Md ∼ 1.6) and superimposed noise to investigate signal-to-noise ratio (SNR) improvement with sensor depth. For the low Q valley fill of the Datil borehole (DBH) site, we have found that SNR can be improved by as much as 20 to 40 dB between 23 and 55 Hz and 10 to 20 dB between 10 and 20 Hz, by deploying at a 43-m depth rather than at the surface. At the surface, there is little signal above noise in the 23- to 55-Hz frequency band for wind speeds greater than 8 m/sec. Thus, high-frequency signal information that is lost at the surface can be recorded by deploying at the relatively shallow depth of 40 m. Because we observe only minor further reductions in seismic background noise (SBN) at deeper depths, 40 m is likely to be a reasonable deployment depth for other high-frequency-monitoring sites in similar environmental and geologic conditions.

Seismic Interferometry Applied to Seismic Background-Noise Field Data

2006 ◽  
Author(s):  
Deyan Draganov ◽  
Kees Wapenaar ◽  
Wim Mulder ◽  
Johannes Singer ◽  
Arie Verdel
Keyword(s):  
Background Noise ◽  
Field Data ◽  
Seismic Interferometry ◽  
Noise Field ◽  
Seismic Background

Seismic Monitoring in Gujarat, India, during 2020 Coronavirus Lockdown and Lessons Learned

2021 ◽  
Vol 92 (2A) ◽  
pp. 849-858 ◽  
Author(s):  
Santosh Kumar ◽  
R. Chaitanya Kumar ◽  
Ketan Singha Roy ◽  
Sumer Chopra
Keyword(s):  
High Frequency ◽  
Background Noise ◽  
Network Reliability ◽  
Signal To Noise Ratio ◽  
Lessons Learned ◽  
Quaternary Sediments ◽  
Positive Aspect ◽  
Seismicity Monitoring ◽  
Using Data ◽  
Seismic Background

Abstract The Gujarat region, situated in the westernmost part of India, experienced a deadly intraplate 2001 Mw 7.6 Bhuj earthquake. In the aftermath of the disaster, the Institute of Seismological Research established the Gujarat (India) seismic network in 2006. The network is being operated in online and offline modes, whereas, seismicity monitoring is being done in near-real-time, using data received from the online seismic stations. The Coronavirus disease-19 lockdown provided an opportunity to assess the network reliability in a difficult and challenging scenario. The positive aspect of the lockdown is reflected in signal-to-noise ratio, which improved significantly at all the sites during the lockdown, with more prominent being at sites located on top of the Quaternary sediments due to the absence of high-frequency anthropogenic noise. A sharp fall in the seismic background noise is noticed at most of the stations during the lockdown period, with respect to the prelockdown period. We used the lockdown data to identify other natural sources of noise, besides anthropogenic. The lockdown helped in solving the enigma of seismicity in certain pockets, which turned out to be related to quarry blasts.

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