Comparison of Multiple Lapse Time Window Analysis and Qopen to determine intrinsic and scattering attenuation

Laaten, M van; Eulenfeld, Tom; Wegler, Ulrich

doi:10.1093/gji/ggab390

Cited by 7 publications

(7 citation statements)

References 49 publications

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“…The MFT can be calculated with more accuracy using the code Qopen (Eulenfeld and Wegler, 2016), which separates intrinsic and scattering attenuation for each event and station by envelope inversion. However, the comparison between Qopen and the MLTWA made by van Laaten et al (2021) shows that both methods give the same values within their error bars.…”

Section: Coda Attenuation Measurements and Mappingmentioning

confidence: 80%

Fast Changes in Seismic Attenuation of the Upper Crust due to Fracturing and Fluid Migration: The 2016–2017 Central Italy Seismic Sequence

et al. 2022

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The Amatrice–Visso–Norcia seismic sequence struck Central Italy across the Apenninic normal fault system in 2016. Fluids likely triggered the sequence and reduced the stability of the fault network following the first earthquake (Amatrice, Mw 6.0), with their migration nucleating the Visso (Mw 5.9) and Norcia (Mw 6.5) mainshocks. However, both spatial extent and mechanisms of fluid migration and diffusion through the network remain unclear. High fluid content, enhanced permeability, and pervasive microcracking increase seismic attenuation, but different processes contribute to different attenuation mechanisms. Here, we measured and mapped peak delay time and coda attenuation, using them as proxies of seismic scattering and absorption before and during the sequence. We observed that the structural discontinuities and lithology control the scattering losses at all frequencies, with the highest scattering delineating carbonate formations within the Gran Sasso massif. The Monti Sibillini thrust marks the strongest contrasts in scattering, indicating a barrier for northward fracture propagation. Absorption does not show any sensitivity to the presence of these main geological structures. Before the sequence, low-frequency high-absorption anomalies distribute around the NW-SE-oriented Apennine Mountain chain. During the sequence, a high-absorption anomaly develops from SSE to NNW across the seismogenic zone but remains bounded north by the Monti Sibillini thrust. We attribute this spatial expansion to the deep migration of CO2-bearing fluids across the strike of the fault network from a deep source of trapped CO2 close to the Amatrice earthquake. Fluids expand SSE-NNW primarily during the Visso sequence and then diffuse across the fault zones during the Norcia sequence.

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Section: Coda Attenuation Measurements and Mappingmentioning

confidence: 80%

Fast Changes in Seismic Attenuation of the Upper Crust due to Fracturing and Fluid Migration: The 2016–2017 Central Italy Seismic Sequence

et al. 2022

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“…To obtain robust Qopen results van Laaten et al. (2021) suggest to use coda time windows with a minimum length of 30 s based on their analysis of attenuation properties along the Leipzig–Regensburg fault zone in Germany. Van Laaten et al.…”

Section: Discussionmentioning

confidence: 99%

“…For a comparison of Qopen and the multiple lapse time window analysis we refer to van Laaten et al. (2021).…”

Section: Methodsmentioning

confidence: 99%

“…We emphasize that our scattering strength and intrinsic attenuation estimates for frequencies up to 200 Hz extend the upper frequency limit of previous studies by several tens of Hertz. To obtain robust Qopen results van Laaten et al (2021) suggest to use coda time windows with a minimum length of 30 s based on their analysis of attenuation properties along the Leipzig-Regensburg fault zone in Germany. Van Laaten et al (2021) used envelopes of 18 earthquakes with local magnitude between 1.4 and 3.0 recorded at 20 broadband stations with event-station distances up to 80 km.…”

Section: Scattering and Intrinsic Attenuation Propertiesmentioning

confidence: 99%

“…To obtain robust Qopen results van Laaten et al (2021) suggest to use coda time windows with a minimum length of 30 s based on their analysis of attenuation properties along the Leipzig-Regensburg fault zone in Germany. Van Laaten et al (2021) used envelopes of 18 earthquakes with local magnitude between 1.4 and 3.0 recorded at 20 broadband stations with event-station distances up to 80 km. In comparison, our analysis here uses shorter event-station distances and our network convinces overall more with a better azimuthal station distribution (Figure 1).…”

Section: Scattering and Intrinsic Attenuation Propertiesmentioning

confidence: 99%

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Induced Earthquake Source Parameters, Attenuation, and Site Effects From Waveform Envelopes in the Fennoscandian Shield

et al. 2023

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We analyze envelopes of 233 and 22 ML0.0 to ML1.8 earthquakes induced by two geothermal stimulations in the Helsinki, Finland, metropolitan area. We separate source spectra and site terms and determine intrinsic attenuation and the scattering strength of shear waves in the 3–200 Hz frequency range using radiative transfer based synthetic envelopes. Displacement spectra yield scaling relations with a general deviation from self‐similarity, with a stronger albeit more controversial signal from the weaker 2020 stimulation. The 2020 earthquakes also tend to have a smaller local magnitude compared to 2018 earthquakes with the same moment magnitude. We discuss these connections in the context of fluid effects on rupture speed or medium properties. Site terms demonstrate that the spectral amplification relative to two reference borehole sites is not neutral at the other sensors; largest variations are observed at surface stations at frequencies larger than 30 Hz. Intrinsic attenuation is exceptionally low with Qi−1 ${Q}_{\mathrm{i}}^{-1}$ values down to 2.4 × 10−5 at 20 Hz, which allows the observation of a diffuse reflection at the ∼50 km deep Moho. Scattering strength is in the range of globally observed data with Qnormalsnormalc−1 ${Q}_{\mathrm{s}\mathrm{c}}^{-1}$ between 10−3 and 10−4. The application of the employed Qopen analysis program to the 2020 data in a retrospective monitoring mode demonstrates its versatility as a seismicity processing tool. The diverse results have implications for scaling relations, hazard assessment and ground motion modeling, and imaging and monitoring using ballistic and scattered wavefields in the crystalline Fennoscandian Shield environment.

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Depth and Spatial Variation of the Shear Wave Attenuation Parameters in the Shallow Crust and Lower Crust/Upper Mantle of Mt. Etna (Italy)

Giampiccolo,

Tuvè,

Bianco

et al. 2024

Pure Appl. Geophys.

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Seismic wave attenuation is a key feature of seismic wave propagation that provides constraints on the composition and physical state of the medium within the Earth. We separated intrinsic and scattering attenuation coefficients for the shallow crust and lower crust/upper mantle in the Mt. Etna area. For this purpose, the Multiple Lapse Time Window Analysis (MLTWA) was applied to two groups of earthquakes, well separated in depth. We also studied the spatial variation of the attenuation parameters by dividing the study area into four sectors around Etna. The results show an effective homogeneity of the propagation characteristics inside Etna and, in particular, some lateral variations and minor variations with depth. We observe that structural discontinuities and lithology control scattering losses at all frequencies, with higher scattering in the shallow crust. The intrinsic absorption shows no sensitivity to the presence of these main geological structures and is quite uniform for different depths. Furthermore, compared to the northern sector of the volcano, the southern one shows stronger scattering attenuation at low frequencies. This pattern correlates well with the high seismic activity along most of Etna’s active tectonic structures and ascending magmatic fluids that characterize this sector of the volcano. Although we only discuss the differences in the "average" scattering and inelastic properties of the investigated volumes, the results of this study are very informative about the characteristics of each region. Moreover, they suggest that a future study is necessary, providing a more detailed picture of the spatial distribution of seismic attenuation in the study area, through a 3D inversion of the attenuation parameters estimated along the single source-receiver paths.

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Comparison of Multiple Lapse Time Window Analysis and Qopen to determine intrinsic and scattering attenuation

Cited by 7 publications

References 49 publications

Fast Changes in Seismic Attenuation of the Upper Crust due to Fracturing and Fluid Migration: The 2016–2017 Central Italy Seismic Sequence

Fast Changes in Seismic Attenuation of the Upper Crust due to Fracturing and Fluid Migration: The 2016–2017 Central Italy Seismic Sequence

Induced Earthquake Source Parameters, Attenuation, and Site Effects From Waveform Envelopes in the Fennoscandian Shield

Depth and Spatial Variation of the Shear Wave Attenuation Parameters in the Shallow Crust and Lower Crust/Upper Mantle of Mt. Etna (Italy)

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