High-resolution seismic survey on the Rhine River in the northern Upper Rhine Graben

Abstract. We perform a fault-based PSHA exercise in the Upper Rhine Graben to quantify the relative influence of fault parameters on the hazard at the Fessenheim Nuclear Power Plant site. Specifically, we show that the potentially active faults described in Part A of this paper (Jomard et al., submitted this issue) are the dominant factor in hazard estimates at the low annual probability of exceedance relevant for the safety assessment of nuclear installations. Geological information documenting the activity of the faults in this region, however, remains sparse, controversial and affected by a high degree of uncertainty. A logic tree approach is thus implemented to explore the epistemic uncertainty and quantify its impact on the seismic hazard estimates. Disaggregation of the Peak Ground Acceleration (PGA) hazard at 10,000 years return period shows that the Rhine River Fault is the main seismic source controlling the hazard level at the site. The choice of Ground Motion Prediction Equations (GMPE) is the major source of uncertainty. Nonetheless the parameters describing the geometry and the seismic activity of the faults (dip, width, slip rate) also have an impact on the result depending on the GMPE used. The uncertainty on the slip rate of the Rhine River Fault is the second most dominant factor controlling the uncertainty on the seismic hazard level. Uncertainty on slip rate estimates from 0.04 mm/yr to 0.1 mm/yr results in up to 40 % increase in hazard levels at the 10,000 years return period target depending on the GMPE used and the spectral frequency of interest. Reducing epistemic uncertainty in future fault-based PSHA studies at this site will thus require (1) performing in-depth field studies to better characterize the seismic potential of the Rhine River Fault; (2) complementing GMPEs with more physics-based modeling approaches to better account for the near-field effects of ground motion and (3) improving the modeling of the background seismicity. Indeed, in this exercise, we assume that background earthquakes can only host M 6.0 earthquakes have been recently identified at depth within the Upper Rhine Graben (see Part A) but are not accounted for in this exercise since their potential activity has not yet been described.

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High-resolution Seismic Imaging of Near-surface Fault Zones in the Upper Rhine Graben, Germany

Near Surface 2009 - 15th EAGE European Meeting of Environmental and Engineering Geophysics ◽

10.3997/2214-4609.20147030 ◽

2009 ◽

Author(s):

P. Musmann ◽

H. Buness ◽

H.M. Rumpel

Keyword(s):

High Resolution ◽

Seismic Imaging ◽

Fault Zones ◽

Upper Rhine Graben ◽

Near Surface ◽

Rhine Graben ◽

Upper Rhine

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The Heidelberg Basin drilling project: Geophysical pre-site surveys

E&G Quaternary Science Journal ◽

10.3285/eg.57.3-4.4 ◽

2009 ◽

Vol 57 (3/4) ◽

pp. 338-366 ◽

Cited By ~ 1

Author(s):

Hermann Buness ◽

Gerald Gabriel ◽

Dietrich Ellwanger

Keyword(s):

Seismic Survey ◽

Upper Rhine Graben ◽

High Temporal Resolution ◽

Special Importance ◽

Seismic Profiles ◽

Reflection Seismic ◽

Rhine Graben ◽

Sediment Deposits ◽

New Research ◽

Upper Rhine

Abstract. Currently, the Heidelberg Basin is under investigation by new cored research boreholes to enhance the understanding concerning the control on Pliocene and Quaternary sedimentation by (neo)tectonics and climate. The Heidelberg Basin is expected to serve as a key location for an improved correlation of parameters that characterise the climate evolution in North Europe and the Alpine region. The recovery of sediment successions of high temporal resolution that are complete with respect to the deposition of Pleistocene glacials and interglacials in superposition is of special importance. Prior to the new research boreholes in Viernheim and Heidelberg geophysical pre-site surveys were performed to identify borehole locations that best achieve these requirements. In the area of the Heidelberg Basin the strongest negative gravity anomaly of the entire Upper Rhine Graben is observed (apart from the Alps), hinting at anomalously thick sediment deposits. However, especially reflection seismic profiles contributed significantly to the decision about the borehole locations. In the city of Heidelberg for the first time, the depocentre of the Heidelberg Basin, as indicated by additional subsidence compared to its surroundings, was mapped. In this area, sediments dip towards the eastern margin of the Upper Rhine Graben. This is interpreted to represent a rollover structure related to the maximum subsidence of the Upper Rhine Graben in this region. At the Viernheim borehole location the seismic survey revealed several faults. Although these faults are mainly restricted to depths greater than 225 m, the borehole location was fi nally adjusted with respect to this information.

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Today's sediment budget of the Rhine River channel, focusing on the Upper Rhine Graben and Rhenish Massif

Geomorphology ◽

10.1016/j.geomorph.2013.08.035 ◽

2014 ◽

Vol 204 ◽

pp. 573-587 ◽

Cited By ~ 28

Author(s):

Roy M. Frings ◽

Nicole Gehres ◽

Markus Promny ◽

Hans Middelkoop ◽

Holger Schüttrumpf ◽

...

Keyword(s):

Sediment Budget ◽

River Channel ◽

Upper Rhine Graben ◽

Rhine River ◽

Rhenish Massif ◽

Rhine Graben ◽

Upper Rhine

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Transposing an active fault database into a fault-based seismic hazard assessment for nuclear facilities – Part 2: Impact of fault parameter uncertainties on a site-specific PSHA exercise in the Upper Rhine Graben, eastern France

Natural Hazards and Earth System Science ◽

10.5194/nhess-17-1585-2017 ◽

2017 ◽

Vol 17 (9) ◽

pp. 1585-1593 ◽

Cited By ~ 5

Author(s):

Thomas Chartier ◽

Oona Scotti ◽

Christophe Clément ◽

Hervé Jomard ◽

Stéphane Baize

Keyword(s):

Seismic Hazard ◽

Epistemic Uncertainty ◽

Slip Rate ◽

Seismic Hazard Assessment ◽

Dominant Factor ◽

Upper Rhine Graben ◽

Rhine River ◽

Rhine Graben ◽

Hazard Level ◽

Upper Rhine

Abstract. We perform a fault-based probabilistic seismic hazard assessment (PSHA) exercise in the Upper Rhine Graben to quantify the relative influence of fault parameters on the hazard at the Fessenheim nuclear power plant site. Specifically, we show that the potentially active faults described in the companion paper (Jomard et al., 2017, hereafter Part 1) are the dominant factor in hazard estimates at the low annual probability of exceedance relevant for the safety assessment of nuclear installations. Geological information documenting the activity of the faults in this region, however, remains sparse, controversial and affected by a high degree of uncertainty. A logic tree approach is thus implemented to explore the epistemic uncertainty and quantify its impact on the seismic hazard estimates. Disaggregation of the peak ground acceleration (PGA) hazard at a 10 000-year return period shows that the Rhine River fault is the main seismic source controlling the hazard level at the site. Sensitivity tests show that the uncertainty on the slip rate of the Rhine River fault is the dominant factor controlling the variability of the seismic hazard level, greater than the epistemic uncertainty due to ground motion prediction equations (GMPEs). Uncertainty on slip rate estimates from 0.04 to 0.1 mm yr−1 results in a 40 to 50 % increase in hazard levels at the 10 000-year target return period. Reducing epistemic uncertainty in future fault-based PSHA studies at this site will thus require (1) performing in-depth field studies to better characterize the seismic potential of the Rhine River fault; (2) complementing GMPEs with more physics-based modelling approaches to better account for the near-field effects of ground motion and (3) improving the modelling of the background seismicity. Indeed, in this exercise, we assume that background earthquakes can only host M < 6. 0 earthquakes. However, this assumption is debatable, since faults that can host M > 6. 0 earthquakes have been recently identified at depth within the Upper Rhine Graben (see Part 1) but are not accounted for in this exercise since their potential activity has not yet been described.

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High-resolution 3D seismic imaging and refined velocity model building improve the image of a deep geothermal reservoir in the Upper Rhine Graben

The Leading Edge ◽

10.1190/tle39120857.1 ◽

2020 ◽

Vol 39 (12) ◽

pp. 857-863

Author(s):

Nicolas Salaun ◽

Helene Toubiana ◽

Jean-Baptiste Mitschler ◽

Guillaume Gigou ◽

Xavier Carriere ◽

...

Keyword(s):

Seismic Data ◽

Large Scale ◽

Model Building ◽

Geothermal Reservoir ◽

Seismic Survey ◽

Upper Rhine Graben ◽

3D Seismic ◽

Rhine Graben ◽

Future Production ◽

Upper Rhine

Over the past 35 years, geothermal projects have been developed in the Upper Rhine Graben (URG) to exploit deep geothermal energy. Underneath approximately 2 km of sedimentary deposits, the deep target consists of a granitic basement, which is highly fractured and hydrothermally altered. Therefore, it has high potential as a geothermal reservoir. Despite dense 2D seismic data coverage originally acquired for oil exploration (for a target two-way traveltime between 300 and 700 ms), the faults at the top of the granitic basement (between 1400 and 4000 ms) are poorly imaged, and their locations remain uncertain. To gain a better understanding of this large-scale faulting and to ensure the viability of future geothermal projects, a 3D seismic survey was acquired in the French part of the URG during the summer of 2018. This paper describes how an integrated project, combining seismic data processing, high-end imaging, and enhanced interpretation, was conducted to improve the understanding of this complex basin for geothermal purposes. By revealing the deep granite layer and its complex associated fault network, the insight from this project can help accurately locate future production wells.

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3D Modelling of the Northern Upper Rhine Graben Crystalline Basement by Joint Inversion of Gravity and Magnetic Data

10.5194/egusphere-egu21-477 ◽

2021 ◽

Author(s):

Matthis Frey ◽

Sebastian Weinert ◽

Kristian Bär ◽

Jeroen van der Vaart ◽

Chrystel Dezayes ◽

...

Keyword(s):

High Resolution ◽

Heat Transport ◽

Joint Inversion ◽

Transport Processes ◽

Crystalline Basement ◽

Magnetic Data ◽

Moho Depth ◽

Upper Rhine Graben ◽

Rhine Graben ◽

Upper Rhine

<p>The crystalline basement of the Upper Rhine Graben presents an attractive target for deep geothermal projects due to its favourable temperatures and its high potential as a fractured and faulted reservoir system. It is already exploited at several sites, e.g. Soultz-sous-For&#234;ts or Landau, and further projects are currently planned or under development. The crystalline units are furthermore the main source of radiogenic heat production and thus, together with the shallow Moho depth and convective heat transport along large fault zones, significantly contributing to the crustal temperature field. For these reasons, we developed the most detailed 3D geological model of the basement in the northern Upper Rhine Graben to date within the Interreg NWE DGE-ROLLOUT and Hesse 3D 2.0 projects. Due to the small number of very deep boreholes as well as seismic profiles reaching the basement beneath the locally more than 5 km thick sedimentary cover, we additionally used high-resolution magnetic and gravity datasets. In contrast to common deterministic modelling approaches, we performed a stochastic joint inversion of the geophysical data by applying a Monte Carlo Markov Chain algorithm. This method generates a large set of random but valid models, which enables a statistical evaluation of the results, e.g. concerning the model uncertainties. For a realistic attribution of the model, we used existing petrophysical databases of the region and measured the magnetic susceptibility of more than 430 rock samples. As a result of the inversion, high-resolution voxel models of the density and susceptibility distribution were generated, allowing conclusions about the composition and structure of the crystalline crust, which leads to a reduction of uncertainties and risks associated with deep geothermal drillings in the northern Upper Rhine Graben. Furthermore, our model will serve as a basis for realistic simulations of heat transport processes in the fractured basement and a meaningful assessment of the deep geothermal potential in the future.</p>

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