Broadband, short-period or geophone nodes? Quality assessment of Passive Seismic signals acquired during the Maupasacq experiment

Polychronopoulou, K.; Lois, Athanasios; Martakis, Nick; Chevrot, Sébastien; Sylvander, Matthieu; Díaz, Jordi; Villaseñor, Antonio; Calassou, Sylvain; Collin, Magali; Masini, Emmanuel; Bitri, Adnand; Stehly, Laurent

doi:10.3997/1365-2397.n0085

Cited by 13 publications

(8 citation statements)

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“…In order to provide independent constraints on the S-wave velocity structure we also show the results of a V S model obtained from local earthquake tomography (Villaseñor et al 2019) using arrival times picked on records from the stations of the Maupasacq experiment. During the 6 months of operation of this temporary network, a total of 1980 local earthquakes were detected and located (Polychronopoulou et al 2018). From this catalog we selected for the tomography well recorded earthquakes with at least 8 P arrival times, 2 S arrival times and an azimuthal gap smaller than 200 degrees.…”

Section: Local Earthquake Tomographymentioning

confidence: 99%

“…The starting model used in the inversion is the 1-D velocity model previously determined for earthquake location (Polychronopoulou et al 2018). The final model shown here was obtained after 10 iterations.…”

Section: Local Earthquake Tomographymentioning

confidence: 99%

“…1). In the inner rectangular grid, the station spacing ranged from 1 km between the geophone nodes to 7 km between the broad-band stations (details in Polychronopoulou et al 2018;Lehujeur & Chevrot 2020).…”

Section: Introductionmentioning

confidence: 99%

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Three-dimensional shear velocity structure of the Mauléon and Arzacq Basins (Western Pyrenees)

Lehujeur¹,

Chevrot²,

Villaseñor³

et al. 2021

BSGF - Earth Sci. Bull.

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We present a 3-D shear wave velocity model of the Mauleon and Arzacq basins from the surface down to 10~km depth. This model is obtained by inverting phase velocity maps for periods from 2 to 9~s measured on coherent surface wavefronts extracted from ambient seismic noise by matched filtering. This new model, which is found in good agreement with local earthquake tomography, reveals the architecture of the Mauleon and Arzacq basins which were poorly imaged by conventional reflection seismic data. Combining these new tomographic images with surface and subsurface geological information allows us to trace major orogenic structures from the basement to the surface. In the basin, the models are successfully imaging first-order folds and thrusts at kilometric scale. The velocity structure within the basement and its geometrical relationship with the base of inverted rift basins supports a progressive northward exhumation of deep crustal and mantle rocks in the hanging wall of north-vergent Pyrenean thrusts. Our tomographic models image in 3-D orogen-perpendicular structures responsible for crustal segmentation as the Saison and Barlanes transfer zones. We propose that these steep structures consist in tear faults that accommodate the deepening of the Mauleon basin basement from west to east. To the west, this basement made of former hyper-extended rift domains (including mantle rocks) is anomalously sampled within the hanging-wall of north-directed orogenic thrusts, explaining its shallow attitude and its best preservation in comparison to the eastern segment of the study area. Eastward, the vertical shift of the basement makes that the former Mauleon basin hyper-extended rift basement remained in a footwall situation in respect of orogenic thrust and was underthrust. The comparison of the tomographic models obtained with surface wave tomography and local earthquake tomography shows that each approach has its own advantages and shortcomings but also that they are very complementary in nature, which would suggest to combine them in joint inversions to further improve passive imaging of the shallow crust and sedimentary basins.

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Section: Local Earthquake Tomographymentioning

confidence: 99%

Section: Local Earthquake Tomographymentioning

confidence: 99%

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Three-dimensional shear velocity structure of the Mauléon and Arzacq Basins (Western Pyrenees)

Lehujeur¹,

Chevrot²,

Villaseñor³

et al. 2021

BSGF - Earth Sci. Bull.

View full text Add to dashboard Cite

show abstract

“…The Maupasacq experiment was mainly designed for the application of LET and ANT and a principal target depth at crustal scale, which is reflected by the choice of sensors, instrument spacing and array aperture (which will be discussed presently). Further details on Maupasacq are provided by [ 17 ]. However, a weak point of the two methods, reinforced by the design, is very limited near surface resolution.…”

Section: Maupasacq Experimentsmentioning

confidence: 99%

“…Additionally, three different instrument types were employed for the experiment in order to establish the ideal use cases for each type. The survey’s acquisition layout was designed to maximise the information that could be obtained from LET and ANT with a target depth in the order of several kilometres [ 17 ]. These depths are beyond the capabilities of HVSR inversions in our experimental setup.…”

Section: Introductionmentioning

confidence: 99%

On the Utility of Horizontal-to-Vertical Spectral Ratios of Ambient Noise in Joint Inversion with Rayleigh Wave Dispersion Curves for the Large-N Maupasacq Experiment

Neukirch

García‐Jerez

Villaseñor

et al. 2021

Sensors

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Horizontal-to-Vertical Spectral Ratios (HVSR) and Rayleigh group velocity dispersion curves (DC) can be used to estimate the shallow S-wave velocity (VS) structure. Knowing the VS structure is important for geophysical data interpretation either in order to better constrain data inversions for P-wave velocity (VP) structures such as travel time tomography or full waveform inversions or to directly study the VS structure for geo-engineering purposes (e.g., ground motion prediction). The joint inversion of HVSR and dispersion data for 1D VS structure allows characterising the uppermost crust and near surface, where the HVSR data (0.03 to 10s) are most sensitive while the dispersion data (1 to 30s) constrain the deeper model which would, otherwise, add complexity to the HVSR data inversion and adversely affect its convergence. During a large-scale experiment, 197 three-component short-period stations, 41 broad band instruments and 190 geophones were continuously operated for 6 months (April to October 2017) covering an area of approximately 1500km2 with a site spacing of approximately 1 to 3km. Joint inversion of HVSR and DC allowed estimating VS and, to some extent density, down to depths of around 1000m. Broadband and short period instruments performed statistically better than geophone nodes due to the latter’s gap in sensitivity between HVSR and DC. It may be possible to use HVSR data in a joint inversion with DC, increasing resolution for the shallower layers and/or alleviating the absence of short period DC data, which may be harder to obtain. By including HVSR to DC inversions, confidence improvements of two to three times for layers above 300m were achieved. Furthermore, HVSR/DC joint inversion may be useful to generate initial models for 3D tomographic inversions in large scale deployments. Lastly, the joint inversion of HVSR and DC data can be sensitive to density but this sensitivity is situational and depends strongly on the other inversion parameters, namely VS and VP. Density estimates from a HVSR/DC joint inversion should be treated with care, while some subsurface structures may be sensitive, others are clearly not. Inclusion of gravity inversion to HVSR/DC joint inversion may be possible and prove useful.

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Design and implementation of seismic data acquisition system using PC/104

et al. 2019

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The seismic data acquisition system from analog to digital data converter has been integrated to develop acquisition device. Contrary to the digitizers currently in use, seismic data acquisition using PC/104, or industrial personal computer, turned out to be able to produce a less expensive digitizer (analog to digital converter) proven able to overcome issues of portability, efficiency, and durability. PC/104 used in this study was Arbor production with the EmCORE n-511 serial number within operating system, and the programming languages are DOS 6.02 and C, respectively. This research resulted in a design of a prototyping device based on PC/104 and created a program to record seismic data. The program was compiled in the Microsoft Windows XP operating system environment using Borland C 5.02 software. The input range of the data acquisition system that has been tested is ± 10 V. The performance test results show a resolution of ± 0.915 mV, a linearity of 0.2% full-scale reading, instrument work noise is ± 1.2 mV with a maximum frequency distortion of 2%. The instrument performs well at a rate of 10 Hz to 5000 Hz, but the software has a limited capacity of only 1000 Hz. From the results of a comparative test with Digitizer Güralp Type CGM-DM16R8, the value of the RMS error is 4.64%.

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Broadband, short-period or geophone nodes? Quality assessment of Passive Seismic signals acquired during the Maupasacq experiment

Cited by 13 publications

References 0 publications

Three-dimensional shear velocity structure of the Mauléon and Arzacq Basins (Western Pyrenees)

Three-dimensional shear velocity structure of the Mauléon and Arzacq Basins (Western Pyrenees)

On the Utility of Horizontal-to-Vertical Spectral Ratios of Ambient Noise in Joint Inversion with Rayleigh Wave Dispersion Curves for the Large-N Maupasacq Experiment

Design and implementation of seismic data acquisition system using PC/104

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