Three-component ambient noise beamforming in the Parkfield area

Löer, Katrin; Riahi, Nima; Saenger, Erik H.

doi:10.1093/gji/ggy058

Cited by 40 publications

(42 citation statements)

References 46 publications

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“…Characterizing the DFN requires access to the reservoir rock at reservoir-related depth, which is not present. However, we have reasonable cause to expect comparable discontinuity orientations in our geological subsurface model, as in our studied outcrops (Lorenz et al, 1991;Narr, 1991). For example, Narr (1991Narr ( , 1996 presented how to derive DFN from drill core samples of reservoirs.…”

Section: Discussionsupporting

confidence: 54%

Characterization of discontinuities in potential reservoir rocks for geothermal applications in the Rhine-Ruhr metropolitan area (Germany)

et al. 2021

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Abstract. The importance of research into clean and renewable energy solutions has increased over the last decade. Geothermal energy provision is proven to meet both conditions. Therefore, conceptual models for deep geothermal applications were developed for different field sites regarding different local conditions. In Bavaria, Germany, geothermal applications were successfully carried out in carbonate horizons at depths of 4000 to 6000 m. Matrix permeability and thermal conductivity was mainly studied in karstified carbonates from the Late Jurassic reef facies. Similar to Bavaria, carbonates are located in the east of the Rhenohercynian Massif, in North Rhine-Westphalia (NRW), for which quantification of the geothermal potential is still lacking. Compared to Bavaria, a supraregional carbonate mountain belt is exposed at the Remscheid-Altena anticline (in NRW) from the Upper Devonian and Lower Carboniferous times. The aim of our study was to examine the potential geothermal reservoir by field and laboratory investigations. Therefore, three representative outcrops in Wuppertal, Hagen-Hohenlimburg, and Hönnetal were studied. During field surveys, 1068 discontinuities (139 open fractures without any filling, 213 joints, 413 veins filled with calcite, and 303 fractures filled with debris deposits) at various spatial scales were observed by scanline surveys. These discontinuities were characterized by trace length, true spacing, roughness, aperture, and filling materials. Discontinuity orientation analysis indicated three dominant strike orientations in NNW–SSE, NW–SE, and NE–SW directions within the target horizon of interest. This compacted limestone layer (Massenkalk) is approximately 150 m thick and located at 4000 to 6000 m depth, dipping northwards at a dip angle of about 30 to 40∘. An extrapolation of the measured layer orientation and dip suggests that the carbonate reservoir could hypothetically extend below Essen, Bochum, and Dortmund. Our combined analysis of the field and laboratory results has shown that it could be a naturally fractured carbonate reservoir. We evaluated the potential discontinuity network in the reservoir and its orientation with respect to the prevailing maximum horizontal stress before concluding with implications for fluid flow: we proposed focusing on prominent discontinuities striking NNW–SSE for upcoming geothermal applications, as these (1) are the most common, (2) strike in the direction of the main horizontal stress, (3) have a discontinuity permeability that significantly exceeds that of the reservoir rock matrix, and (4) only about 38 % of these discontinuities were observed with a calcite filling. The remaining discontinuities either showed no filling material or showed debris deposits, which we interpret as open at reservoir depth. Our results indicate that even higher permeability can be expected for karstified formations related to the reef facies and hydrothermal processes. Our compiled data set, consisting of laboratory and field measurements, may provide a good basis for 3D subsurface modelling and numerical prediction of fluid flow in the naturally fractured carbonate reservoir.

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Section: Discussionsupporting

confidence: 54%

Characterization of discontinuities in potential reservoir rocks for geothermal applications in the Rhine-Ruhr metropolitan area (Germany)

et al. 2021

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“…To characterize the wavefield's azimuthal dependence at a given station, we adopted a beamform approach and used a plane wave approximation to find the best-fitting slowness for every possible azimuth range (19,20). For this process, we searched for the maximum coherent output over velocities from 1 to 5 km/s in 5° bins from 0° to 360° azimuth with 70% overlap for the 3-to 17-s period band.…”

Section: Azimuthal Anisotropy Measurementsmentioning

confidence: 99%

“…With the concentration of broadband stations in the area and wide azimuthal interstation path coverage, we can reliably resolve the lateral variations of seismic anisotropy for the uppermost ~35 km of the crust. To measure the anisotropy, we implemented a beamforming scheme that allows us to characterize the seismic wavefield's velocity dependence with propagation direction beneath each station (19,20). The reliability of our model was then verified by comparing our surface wave anisotropy measurements to those that were obtained by characterizing the azimuthal dependence of receiver functions (RFs) at stations surrounding the Wallowa Mountains ( fig.…”

Section: Introductionmentioning

confidence: 99%

Seismic anisotropy reveals crustal flow driven by mantle vertical loading in the Pacific NW

et al. 2020

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Buoyancy anomalies within Earth’s mantle create large convective currents that are thought to control the evolution of the lithosphere. While tectonic plate motions provide evidence for this relation, the mechanism by which mantle processes influence near-surface tectonics remains elusive. Here, we present an azimuthal anisotropy model for the Pacific Northwest crust that strongly correlates with high-velocity structures in the underlying mantle but shows no association with the regional mantle flow field. We suggest that the crustal anisotropy is decoupled from horizontal basal tractions and, instead, created by upper mantle vertical loading, which generates pressure gradients that drive channelized flow in the mid-lower crust. We then demonstrate the interplay between mantle heterogeneities and lithosphere dynamics by predicting the viscous crustal flow that is driven by local buoyancy sources within the upper mantle. Our findings reveal how mantle vertical load distribution can actively control crustal deformation on a scale of several hundred kilometers.

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“…-Three-component beamforming (e.g., Löer et al, 2018), which can help to identify the types of waves arriving at the array by providing information on the polarization of the wavefield. This, alongside the location from more traditional beamforming approaches, could help place further constraints on the characteristics of the tremor source.…”

Section: Tremor Location Methods and Features For Future Versionsmentioning

confidence: 99%

RETREAT: A REal-Time TREmor Analysis Tool for Seismic Arrays, With Applications for Volcano Monitoring

Smith

Bean

2020

Front. Earth Sci.

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Three-component ambient noise beamforming in the Parkfield area

Cited by 40 publications

References 46 publications

Characterization of discontinuities in potential reservoir rocks for geothermal applications in the Rhine-Ruhr metropolitan area (Germany)

Characterization of discontinuities in potential reservoir rocks for geothermal applications in the Rhine-Ruhr metropolitan area (Germany)

Seismic anisotropy reveals crustal flow driven by mantle vertical loading in the Pacific NW

RETREAT: A REal-Time TREmor Analysis Tool for Seismic Arrays, With Applications for Volcano Monitoring

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