Improving ambient noise correlation functions with an SVD-based Wiener filter

Moreau, Ludovic; Stehly, Laurent; Boué, Pierre; Lu, Yang; Larose, Éric; Campillo, Míchel

doi:10.1093/gji/ggx306

Cited by 70 publications

(56 citation statements)

References 17 publications

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“…The cross‐correlations were then calculated between each virtual source and all the receivers, resulting in 24 cross‐correlations for each stations pair. To obtain the final NCF, the filter introduced in Moreau, Stehly et al () was applied to each set of cross‐correlations, which were finally stacked. The purpose of this filter is to minimize the incoherent information in the singular vectors of the matrix of pre‐stack correlations with the Wiener filter, for improved convergence of the NCF.…”

Section: Resultsmentioning

confidence: 99%

Sea Ice Thickness and Elastic Properties From the Analysis of Multimodal Guided Wave Propagation Measured With a Passive Seismic Array

et al. 2020

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Field data are needed for a better understanding of sea ice decline in the context of climate change. The rapid technological and methodological advances of the last decade have led to a reconsideration of seismic methods in this matter. In particular, passive seismology has filled an important gap by removing the need to use active sources. We present a seismic experiment where an array of 247 geophones was deployed on sea ice, in the Van Mijen fjord near Sveagruva (Svalbard). The array is a mix of 1C and 3C stations with sampling frequencies of 500 and 1000 Hz. They recorded continuously the ambient seismic field in sea ice between 28 February and 26 March 2019. Data also include active acquisitions on 1 and 26 March with a radar antenna, a shaker unit, impulsive sources, and artificial sources of seismic noise. This data set is of unprecedented quality regarding sea ice seismic monitoring, as it also includes thousands of microseismic events recorded each day. By combining passive seismology approaches with specific array processing methods, we demonstrate that the multimodal dispersion curves of sea ice can be calculated without an active source and then used to infer sea ice properties. We calculated an ice thickness, Young's modulus, and Poisson's ratio with values h = 54 ± 3 cm, E = 3.9 ± 0.15 GPa, and = 0.34 ± 0.02 on 1 March, and h = 58 ± 3 cm, E = 4.4 ± 0.15 GPa, and = 0.32 ± 0.02 on 5 March. These values are consistent with in situ field measurements and observations.

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Section: Resultsmentioning

confidence: 99%

Sea Ice Thickness and Elastic Properties From the Analysis of Multimodal Guided Wave Propagation Measured With a Passive Seismic Array

et al. 2020

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“…The next step was to filter the correlograms to enhance the signal-to-noise ratio by applying a Singular Value Decomposition-based Wiener filter 71 . The parameters used for this filter were K = 7, L = 7, the filter orders applied to the vertical and horizontal dimensions, respectively, and the number of first singular values was N = 30.…”

Section: Methodsmentioning

confidence: 99%

Rain and small earthquakes maintain a slow-moving landslide in a persistent critical state

et al. 2020

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In tectonically active mountain belts, landslides contribute significantly to erosion. Statistical analysis of regional inventories of earthquake-triggered-landslides after large earthquakes (Mw > 5.5) reveal a complex interaction between seismic shaking, landslide material, and rainfall. However, the contributions of each component have never been quantified due to a lack of in-situ data for active landslides. We exploited a 3-year geodetic and seismic dataset for a slow-moving landslide in Peru affected by local earthquakes and seasonal rainfalls. Here we show that in combination, they cause greater landslide motion than either force alone. We also show the rigidity of the landslide's bulk clearly decreasing during Ml ≥ 5 earthquakes. The recovery is affected by rainfall and small earthquakes (Ml < 3.6), which prevent the soil from healing, highlighting the importance of the timing between forcings. These new quantitative insights into the mechanics of landslides open new perspectives for the study of the mass balance of earthquakes.

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“…Green's functions are then reconstructed by computing cross correlations for all of the station pairs within each array using the hourly noise data. We apply a two‐dimensional Wiener filter to enhance the signal‐to‐noise ratio, with a filter order of 3 for both vertical (hour) and horizontal (time lag) dimensions (Wang, Tilmann, et al, ; Moreau et al, ) (see the supporting information). For each receiver pair, a reference cross‐correlation function is obtained by stacking cross correlations for that pair over the entire study period.…”

Section: Methodsmentioning

confidence: 99%

High Temporal Resolution Monitoring of Small Variations in Crustal Strain by Dense Seismic Arrays

Mao

Campillo

Hilst

et al. 2019

Geophysical Research Letters

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We demonstrate the feasibility of detecting very weak deformation in the shallow crust with high temporal resolution by monitoring the relative changes in seismic wave velocity (dv/v) using dense arrays of seismometers. We show that the dv/v variations are consistent between independent measurements from two seismic arrays. Dominant peaks in the observed dv/v spectrum suggest that tides and temperature changes are the major causes of daily and subdaily velocity changes, in accordance with theoretical strain modeling. Our analysis illustrates that dv/v perturbations of the order of 10−4, corresponding to crustal strain changes of the order of 10−8, can be measured from ambient seismic noise with a temporal resolution of 1 hr. This represents a low‐cost technique for high precision and high time‐resolution monitoring of crustal deformation that is complementary to existing geodetic measurements and is instrumental in both the detection and understanding of low‐amplitude precursory processes of natural catastrophic events.

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Improving ambient noise correlation functions with an SVD-based Wiener filter

Cited by 70 publications

References 17 publications

Sea Ice Thickness and Elastic Properties From the Analysis of Multimodal Guided Wave Propagation Measured With a Passive Seismic Array

Sea Ice Thickness and Elastic Properties From the Analysis of Multimodal Guided Wave Propagation Measured With a Passive Seismic Array

Rain and small earthquakes maintain a slow-moving landslide in a persistent critical state

High Temporal Resolution Monitoring of Small Variations in Crustal Strain by Dense Seismic Arrays

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