Geopsy: A User-Friendly Open-Source Tool Set for Ambient Vibration Processing

Wathelet, Marc; Chatelain, Jean‐Luc; Cornou, Cécile; Giulio, Giuseppe Di; Guillier, Bertrand; Ohrnberger, Matthias; Savvaidis, Alexandros

doi:10.1785/0220190360

Cited by 262 publications

(163 citation statements)

References 35 publications

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“…The posterior distribution is the product of the likelihood and the prior information. Here, the likelihood is based upon fitting theoretical dispersion curves to those observed, assuming a normal distribution with a mean given by the forward model calculated using the Geopsy algorithm (Wathelet et al, 2020) and standard deviation σ . The GPR and refraction data determine the vertical extent of three internal layers: unsaturated firn, aquifer, and ice.…”

Section: Methodsmentioning

confidence: 99%

Integrated Borehole, Radar, and Seismic Velocity Analysis Reveals Dynamic Spatial Variations Within a Firn Aquifer in Southeast Greenland

Killingbeck

Schmerr

Montgomery

et al. 2020

Geophysical Research Letters

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Perennial water storage in firn aquifers has been observed within the lower percolation zone of the southeast Greenland ice sheet. Spatially distributed seismic and radar observations, made~50 km upstream of the Helheim Glacier terminus, reveal spatial variations of seismic velocity within a firn aquifer. From 1.65 to 1.8 km elevation, shear-wave velocity (Vs) is 1,290 ± 180 m/s in the unsaturated firn, decreasing below the water table (~15 m depth) to 1,130 ± 250 m/s. Below 1.65 km elevation, Vs in the saturated firn is 1,270 ± 220 m/s. The compressional-to-shear velocity ratio decreases in the downstream saturated zone, from 2.30 ± 0.54 to 2.01 ± 0.46, closer to its value for pure ice (2.00). Consistent with colocated firn cores, these results imply an increasing concentration of ice in the downstream sites, reducing the porosity and storage potential of the firn likely caused by episodic melt and freeze during the evolution of the aquifer.

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Section: Methodsmentioning

confidence: 99%

Integrated Borehole, Radar, and Seismic Velocity Analysis Reveals Dynamic Spatial Variations Within a Firn Aquifer in Southeast Greenland

Killingbeck

Schmerr

Montgomery

et al. 2020

Geophysical Research Letters

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“…9a). Dispersion curves were extracted by using the 3-component RTBF algorithm (Wathelet et al, 2018) implemented in the Geopsy software (Wathelet et al, 2020) which allows to extract phase velocities of Rayleigh and Love waves, as well as the signed ellipticity of Rayleigh waves. Dispersion estimates of both Rayleigh and Love waves are very clear from 0.1 Hz to 0.5 Hz (Figure 9b-c-d).…”

Section: A Peculiar Velocity Structure In the Epicenter Areamentioning

confidence: 99%

Rapid response to the Mw 4.9 earthquake of November 11, 2019 in Le Teil, Lower Rhône Valley, France

Cornou¹,

Ampuero²,

Aubert³

et al. 2020

Preprint

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On November 11, 2019, a Mw 4.9 earthquake hit the region close to Montelimar (lower Rhône Valley, France), on the eastern margin of the Massif Central close to the external part of the Alps. Occuring in a moderate seismicity area, this earthquake is remarkable for its very shallow focal depth (between 1 and 3 km), its magnitude, and the moderate to large damages it produced in several villages. InSAR interferograms indicated a shallow rupture about 4 km long reaching the surface and the reactivation of the ancient NE-SW La Rouviere normal fault in reverse faulting in agreement with the present-day E-W compressional tectonics. The peculiarity of this earthquake together with a poor coverage of the epicentral region by permanent seismological and geodetic stations triggered the mobilisation of the French post-seismic unit and the broad French scientific community from various institutions, with the deployment of geophysical instruments (seismological and geodesic stations), geological field surveys, and field evaluation of the intensity of the earthquake. Within 7 days after the mainshock, 47 seismological stations were deployed in the epicentral area to improve the Le Teil aftershocks locations relative to the French permanent seismological network (RESIF), monitor the temporal and spatial evolution of microearthquakes close to the fault plane and temporal evolution of the seismic response of 3 damaged historical buildings, and to study suspected site effects and their influence in the distribution of seismic damage. This seismological dataset, completed by data owned by different institutions, was integrated in a homogeneous archive and distributed through FDSN web services by the RESIF data center. This dataset, together with observations of surface rupture evidences, geologic, geodetic and satellite data, will help to unravel the causes and rupture mechanism of this earthquake, and contribute to account in seismic hazard assessment for earthquakes along the major regional Cévenne fault system in a context of present-day compressional tectonics.

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“…Long-duration recordings (31) have been conducted (at least 40 min) with high-sensitive tromographs, in particular: (1) Trillium® 20 s, with Centaur digitizing apparatus, manufactured by Nanometrics (Canada); (2) Lennartz 3D lite 1 s, with DATA-CUBE 3 (GFZ and Omnirecs/DiGOS). The RPs have been obtained processing HVSR recordings according to sesame criteria (Sesame 2004) as reported in Sandron et al 2019, by means of the open source software Geopsy (Wathelet et al 2020).…”

Section: Passive Seismic Surveys In Kathmandumentioning

confidence: 99%

Mapping long-period soil resonances in the Kathmandu basin using microtremors

et al. 2021

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This study reports the geostatistical analysis of a set of 40 single-station horizontal-to-vertical spectral ratio (HVSR) passive seismic survey data collected in the Kathmandu basin (Nepal). The Kathmandu basin is characterized by a heterogeneous sedimentary cover and by a complex geo-structural setting, inducing a high spatial variability of the bedrock depth. Due to the complex geological setting, the interpretation and analysis of soil resonance periods derived from the HVSR surveys is challenging, both from the perspective of bedrock depth estimation as well as of seismic-site effects characterization. To exploit the available information, the HVSR data are analyzed by means of a geostatistical approach. First, the spatial continuity structure of HVSR data is investigated and interpreted taking into consideration the geological setting and available stratigraphic and seismic information. Then, the exploitation of potential auxiliary variables, based on surface morphology and distance from outcropping bedrock, is evaluated. Finally, the mapping of HVSR resonance periods, together with the evaluation of interpolation uncertainty, is obtained by means of kriging with external drift interpolation. This work contributes to the characterization of local seismic response of the Kathmandu basin. The resulting map of soil resonance periods is compatible with the results of preceding studies and it is characterized by a high spatial variability, even in areas with a deep bedrock and long resonance periods.

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Geopsy: A User-Friendly Open-Source Tool Set for Ambient Vibration Processing

Cited by 262 publications

References 35 publications

Integrated Borehole, Radar, and Seismic Velocity Analysis Reveals Dynamic Spatial Variations Within a Firn Aquifer in Southeast Greenland

Integrated Borehole, Radar, and Seismic Velocity Analysis Reveals Dynamic Spatial Variations Within a Firn Aquifer in Southeast Greenland

Rapid response to the Mw 4.9 earthquake of November 11, 2019 in Le Teil, Lower Rhône Valley, France

Mapping long-period soil resonances in the Kathmandu basin using microtremors

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