Detection of the deep cavern at the Felsopeteny, Hungary site using seismic ambient noise data

2020 ◽  
Author(s):  
Miriam Kristekova ◽  
Jozef Kristek ◽  
Peter Moczo ◽  
Peter Labak
Keyword(s):  
Free Surface ◽  
Ambient Noise ◽  
Spectral Power ◽  
Hydrothermal Activity ◽  
Underground Cavity ◽  
Seismic Ambient Noise ◽  
Nuclear Explosions ◽  
Passive Seismic ◽  
Noise Data ◽  
Sandstone Formation

<p>Nuclear explosions are banned by the Comprehensive Nuclear-Test-Ban Treaty (CTBT). Obviously, the CTBT needs robust and comprehensive verification tools to make sure that no nuclear explosion goes undetected. The detection of underground cavity due to nuclear explosions is a primary task for an on-site inspection (OSI) and resonance seismometry. Recently we have developed the finite-frequency-range spectral-power method that makes it possible to use seismic ambient noise recorded at the free surface above an underground cavity for localizing it. In this contribution we present results of application of the method to data recorded at a site of the Great Cavern near Felsopeteny, Hungary.</p><p>CTBTO performed several active and passive seismic measurements at the free surface above the Great Cavern in September 2019. Seismic ambient noise was recorded one week continuously at almost 50 stations with interstation distance around 50 m covering area 400 x 400 m.</p><p>The oval shaped cavern with a diameter of 28 m located 70 m below the surface was discovered within a clay mine in N-Hungary. The deep basement is composed of Triassic limestone, the cavern is in the overlying Oligocene sandstone formation. As a result of hydrothermal activity in the Pleistocene a cave formed in the limestone which may have collapsed over time. The opening of the deep part of the cave influenced the overlying sandstone formation but the collapse did not reach the surface.</p><p>We present the procedure of pre-processing and identification of a position of the cavern based on the recorded seismic ambient noise. We checked robustness of the obtained results. The results demonstrate potential of our methodology for the OSI purposes.</p>

scholarly journals Passive Seismic Ambient Noise Surface Wave Tomography Applied to Two Exploration Targets in Ontario, Canada

2019 ◽  
Vol 2019 (1) ◽  
pp. 1-3
Author(s):  
Richard Lynch ◽  
Dan Hollis ◽  
John McBride ◽  
Nick Arndt ◽  
Florent Brenguier ◽  
...  
Keyword(s):  
Surface Wave ◽  
Ambient Noise ◽  
Surface Wave Tomography ◽  
Seismic Ambient Noise ◽  
Passive Seismic ◽  
Wave Tomography

Passive seismic ambient noise surface wave tomography applied to two exploration targets in Ontario, Canada

2019 ◽  
Author(s):  
Richard Lynch ◽  
Dan Hollis ◽  
John McBride ◽  
Nick Arndt ◽  
Florent Brenguier ◽  
...  
Keyword(s):  
Surface Wave ◽  
Ambient Noise ◽  
Surface Wave Tomography ◽  
Seismic Ambient Noise ◽  
Passive Seismic ◽  
Wave Tomography

Passive estimation of scattering and intrinsic absorption parameters at 18 active volcanoes in Japan using envelopes of seismic ambient noise cross-correlation functions

2021 ◽  
Author(s):  
Takashi Hirose ◽  
Hideki Ueda ◽  
Eisuke Fujita
Keyword(s):  
Ambient Noise ◽  
Cross Correlation ◽  
Complex Structure ◽  
Estimation Method ◽  
Seismic Ambient Noise ◽  
Intrinsic Absorption ◽  
Noise Data ◽  
Volcanic Islands ◽  
Noise Cross Correlation ◽  
Active Volcanoes

<p>    Estimating seismic scattering and intrinsic absorption parameters, which are measures of medium heterogeneity, is important for understanding the complex structure in shallow regions of volcanoes. In recent years, seismic ambient noise cross-correlation functions (CCFs) have been used instead of records of natural earthquakes or active seismic experiments to estimate those parameters (e.g., Hirose et al., 2019; Hirose et al., 2020; van Dinther et al., 2020). This passive approach possibly allows us to estimate scattering and intrinsic absorption parameters in previously unmeasured regions and frequency bands. In this study, we apply the passive estimation method proposed by Hirose et al. (2019) to 18 active volcanoes in Japan and measure those parameters of Rayleigh waves. We used three-component seismic ambient noise data in the frequency bands of 0.5-1 Hz, 1-2 Hz, and 2-4 Hz at seismic stations of NIED, JMA, HSRI, and MFRI. Before computing CCFs, the temporal flattening technique (Weaver, 2011) was applied to ambient noise data for reducing the effect of temporal fluctuations in noise levels with retaining relative amplitudes among the stations. Daily CCFs of three components (ZZ, ZR, ZT) were computed by stacking 10-minutes-CCFs. We stacked daily CCFs over 1 year and computed mean squared envelopes by smoothing squared amplitude with 4 s (0.5-1 Hz), 2 s (1-2 Hz), or 1 s (2-4 Hz) long time windows. Scattering and intrinsic absorption parameters were estimated by modeling the space-time distributions of energy densities calculated from CCFs with 2D radiative transfer theory. Best-fit values of scattering mean free path at the 18 active volcanoes range between 1.0-4.6 km at 0.5-1Hz band, 0.7-2.9 km at 1-2 Hz band, and 0.9-2.9 km at 2-4 Hz band, respectively. These values are 2 orders of magnitude shorter than those in non-volcanic regions (e.g., Sato et al., 2012). Those of intrinsic absorption parameter range between 0.05-0.26 s<sup>-1</sup> at the 0.5-1 Hz band, 0.06-0.24 s<sup>-1</sup> at the 1-2 Hz band, and 0.06-0.32 s<sup>-1 </sup>at the 2-4 Hz band, respectively. They are at most one order of magnitude larger than those in the non-volcanic regions. Especially strong intrinsic attenuations are estimated at volcanic islands. Water-bearing layers at a depth of several hundred meters below these islands may cause such strong intrinsic attenuations. The frequency dependence of scattering attenuations is also strong at these volcanic islands, suggesting non-uniform structures that largely fluctuate along depths. The results of this study suggest that the passive estimation method of scattering and intrinsic absorption parameters proposed by Hirose et al. (2019) is applicable to various volcanoes. Comparing estimated values of these parameters at various volcanoes will improve our understanding of complex structure at the shallow regions of volcanoes. Moreover, the parameters estimated in this study will boost locating spatial distributions of seismic velocity and/or scattering property changes associated with volcanic activities at the 18 volcanoes.</p><p>Acknowledgments: We used seismograms recorded by Japan Meteorological Agency (JMA), Hot Springs Research Institute (HSRI) of Kanagawa Prefecture, and Mount Fuji Research Institute (MFRI), Yamanashi Prefectural Government.</p>

scholarly journals Monitoring of fields using body and surface waves reconstructed from passive seismic ambient noise

2019 ◽  
Author(s):  
Florent Brenguier ◽  
Aurélien Mordret ◽  
Richard Lynch ◽  
Roméo Courbis ◽  
Xander Campbell ◽  
...  
Keyword(s):  
Surface Waves ◽  
Ambient Noise ◽  
Seismic Ambient Noise ◽  
Passive Seismic

scholarly journals Processing seismic ambient noise data to obtain reliable broad-band surface wave dispersion measurements

2007 ◽  
Vol 169 (3) ◽  
pp. 1239-1260 ◽  
Author(s):  
G. D. Bensen ◽  
M. H. Ritzwoller ◽  
M. P. Barmin ◽  
A. L. Levshin ◽  
F. Lin ◽  
...  
Keyword(s):  
Surface Wave ◽  
Ambient Noise ◽  
Broad Band ◽  
Wave Dispersion ◽  
Surface Wave Dispersion ◽  
Seismic Ambient Noise ◽  
Noise Data

scholarly journals Monitoring of fields using body and surface waves reconstructed from passive seismic ambient noise

2019 ◽  
Author(s):  
Florent Brenguier ◽  
Aurélien Mordret ◽  
Richard Lynch ◽  
Roméo Courbis ◽  
Xander Campbell ◽  
...  
Keyword(s):  
Surface Waves ◽  
Ambient Noise ◽  
Seismic Ambient Noise ◽  
Passive Seismic

The Finite-interval Spectral Power method for detecting underground cavities using seismic ambient noise

2020 ◽  
Vol 224 (2) ◽  
pp. 945-960
Author(s):  
Miriam Kristekova ◽  
Jozef Kristek ◽  
Peter Moczo ◽  
Peter Labak
Keyword(s):  
Ambient Noise ◽  
Finite Interval ◽  
Nuclear Explosion ◽  
Spectral Power ◽  
Automatic Identification ◽  
Underground Nuclear Explosion ◽  
Seismic Ambient Noise ◽  
Single Station ◽  
Underground Cavities ◽  
To Come

SUMMARY Undetected natural and man-made cavities pose a serious geotechnical hazard to human safety. It is therefore important to develop methods for identifying and locating underground cavities in urban development and civil construction. Another important type of cavity is the one generated by an underground nuclear explosion. Identification and location of such cavities is an important proof in case of suspicion of violating the Comprehensive Nuclear-Test-Ban Treaty (CTBT), an international treaty banning nuclear weapon test explosion or any other nuclear explosion which is yet to come into force. We present a new method for detecting and locating a horizontal position of cavity which uses the Finite-interval Spectral Power of seismic ambient noise. The method makes it possible to use single-station measurements at a set of potentially irregularly distributed points in the area on the Earth's free surface over a suspected cavity. Because the method gives better results for undistorted segments of noise records, we also present a method of automatic identification of such segments. We tested our method using records of noise from a site near the Felsőpetény, Hungary, which were collected for the CTBT Organization during a field test in the framework of developing on-site inspection capabilities. The method is ready for further tests in different cavity conditions and applications.

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