Assessing Active Lithospheric Deformations Around the

KIT – University of the State of Baden-Wuerttemberg and National Research Center of the Helmholtz Association

Bauingenieur-. Geo- und Umweltwissenschaften / Physik

www.kit.edu

Antragstellung:Prof. Dr. R.O. Greiling, Institute for Applied Geosciences PD Dr. J. Ritter, Geophysical Institute Dr. M. Westerhaus, Geodetic Institute Dr. G. Huber, Institute for Soil and Rock Mechanics

Assessing Active Lithospheric Deformations Around the Staufen Geothermal Site

Contributions from structural geology, geodesy, seismology and geotechnics



www.kit.edu





www.kit.edu



Bearbeitung:Hennes Obermeyer, GE & O,Dr. M. Lichtenberger, Geo-Lichtenberger Tobias Baumann, Geophysical Institute Andreas Schenk, Geodetic Institute Dr. Peter Kudella, Institute for Soil and Rock Mechanics

Report STUB project 20094 28.04.2010 Kompetenzfeldtreffen "Geosphäre und Risikomanagement"

Staufen: tectonic/geologic situation

Quelle: Sachstandsbericht zur Erkundung und Sanierung des Schadensfalls Staufen, C. Ruch und G. Wirsing, LGRB, 22.02.2010

Schreiner (1991), Genser(1992), Sass (2009)


Investigation site: Staufen im Breisgau

Chronology:Sept 2007: drilling of 7 geothermal wells with a depth of ~ 140 m End of 2007: first reports about structural damage


Staufen: examples for structural damage



Chronology:Sept 2007: drilling of 7 geothermal wells with a depth of ~ 140 m End of 2007: first reports about structural damageJan. 2008: start of repeated levellings (Büro Fritz; since May 2008 Landratsamt Breisgau/Hochschwarzwald) Continuous uplift, max. 11mm/month Hypothesis: reaction of anhydrite with infiltrating groundwater


Uplift determined from repeated levelling



Chronology:Sept 2007: drilling of 7 geothermal wells with a depth of ~ 140 m End of 2007: first reports about structural damageJan. 2008: start of repeated levellings (Büro Fritz; since May 2008 Landratsamt Breisgau/Hochschwarzwald) Continuous uplift, max. 11mm/month Hypothesis: reaction of anhydrite with infiltrating groundwater

March 2009: STUB applicationMarch 2009: beginning of countermeasures drilling of 2 exploration wells by Landesamt für Geologie, Rohstoffe und

Bergbau (LGRB) Reduction of water pressure by pumping Injection of special concrete

Feb 2010: LGRB report, http://www.lgrb.uni-freiburg.de/lgrb/home/schadensfall_staufen


Methods and objectives of STUB application

Geodesy: application of X-band SAR interferometry to determine the surface displacement field

Seismology: compilation of historic and recent seismic activity in the southern Rhine Graben and measurement of microseismicity in Staufen

Geology: localisation of active faults and domains of stress concentration by natural electromagnetic radiation (EMR)

Geotechnics: assessment and modelling of structural damages


In close cooperation with Landratsamt Breisgau – Hochschwarzwald, Außenstelle Müllheim, the geodetic investigations should address the following questions:

Geodesy: questions and problems

Is it possible to quantify the small scale displacement field by X-band SAR-Interferometry?

Are the results of terrestrial levelling corroborated by the spatially dense SAR data?

Is the extension of the levelling network sufficient to cover the whole uplifting area?

Is the uplift restricted to the city center, or are there related movements in other parts of the city (e.g. industrial area Geisgraben) ?


Baseline plot

Geodesy: X-band SAR interferometry

30 scenes of the satellite TerraSAR-X have been acquired from STUB funding, covering the time period Jan. 2008 until Nov. 2009



Intensity of the back scattered radar signal

Phase difference obtained by subtracting two radar images of the same area. The phase difference can be directly converted to ground displacement

+π

−π

2π = 16mm LOS Displacement

Interferogram 25-Jan-2009 - 16-Feb-2009


18-Okt-2008 bis 20-Nov-2008 03-Jan-2009 bis 14-Jan-2009 25-Jan-2009 bis 16-Feb-2009

16-Feb-2009 bis 27-Feb-2008 12-Apr-2009 bis 26-Mai-2009 06-Jun-2009 bis 17-Jun-2009

+π

−π

2π = 16mm LOS Displacement

33d 11d

11d 11d

33d

44d



3404750

3404750

3405000

3405000

3405250

3405250

3405500

3405500

5 3 05 2 5 0

5 3 05 2 5 0

5 3 05 5 0 0

5 3 05 5 0 0

5 3 05 7 5 0

5 3 05 7 5 0

5 3 06 0 0 0

5 3 06 0 0 0

Vertical Displacement [m/month]

-0,01 - -0,01-0,01 - -0,008-0,008 - -0,006-0,006 - -0,004-0,004 - -0,002-0,002 - 0,0020,002 - 0,0040,004 - 0,0060,006 - 0,0080,008 - 0,010,01 - 0,0120,012 - 0,0140,014 - 0,016


Mean displacement rate (10/2008 - 07/2009)

Processing:

Assumption of linear motion and stacking of geocoded inter-ferograms

Conversion of phase to vertical displace-ment

Unstable scatteres and region of low coherence are masked out

Uplift is confined to the city center


Geodesy: interferometry vs. levellingDisplacement Rates[mm/month]Vertical Displacement

-2.0 - 2.0

2.0 - 4.0

4.0 - 6.0

6.0 - 8.0

8.0 - 10.0

10.0 - 12.0

12.0 - 14.0

14.0 - 16.0

0 40 8020 Meters

Levelling network covers the deforming area completely

Asymmetric shape of the uplift hump: larger gradients in SE

Uplift interpolated from levelling


Spatial gradients: an explanation for severe damage ?

Displacement Rates[mm/month]Vertical Displacement

-2.0 - 2.0

2.0 - 4.0

4.0 - 6.0

6.0 - 8.0

8.0 - 10.0

10.0 - 12.0

12.0 - 14.0

14.0 - 16.0

0 40 8020 Meters


Displacement Rates[mm/month]Vertical Displacement

-2.0 - 2.0

2.0 - 4.0

4.0 - 6.0

6.0 - 8.0

8.0 - 10.0

10.0 - 12.0

12.0 - 14.0

14.0 - 16.0

0 40 8020 Meters0 40 8020 Meters

Displacement Rates[mm/month]Difference InSAR - Leveling

-4.0 - -2.0

-2.0 - 2.0

2.0 - 4.0

4.0 - 6.0

Horizontal movements: an explanation for severe damage ?

There are only few indications for horizontal displace-ments from terrestrial observations

Horizontal movement is a possible explanation for the excess displace-ments seen by SAR


ResultsThe independent SAR method corroborated the terrestrial observationsThe spatially dense SAR data helped to asses extension and shape of the uplifting region. Uplift is confined to the center of the city; no significant displacements occurs in the periphery. Indications for horizontal displacements

Outcome and ongoing work Quantification of the horizontal displacement field from a combination of

ascending and descending orbit acquisitions as well as levelling data Application of Persistent-Scatterer SAR-interferometric techniques Analysis of historical C-band data dating back to 1992 Lessions learnt will be incorporated into a running doctoral theses and

into projects on monitoring geothermal or oil production sites (e.g. Speyer, Landau)



Seismology: compilation of seismic activity

Seismicity in the southern Upper Rhine Graben. Epicentres: blue after Leydecker (800-1971); red: nrift.34 catalogue from Bonjer; yellow: State Geological Survey, Freiburg.


Seismology: compilation of seismic activity

Hypocentral parameters of the most recent earthquakes close to Staufen, data source: catalogue of the Landeserdbebendienst, Freiburg (State Geological Survey).

Conclusion: there is no seismic event that could be related to the uplift process which started at the end of year 2007


Seismology: measurement of microseismicity

Urban Seismology 2 (URS2):Installation of 9 broadband seismic stations provided by the Karlsruhe BroadBand Array (KABBA)Extension of the network by two additional mini-arrays of 4 stations and detonation of artificial sources during one night in September 2009Uplifting region



ResultsVery high cultural noise in the urban environment (normally not used for seismic studies)Numerous transient (traffic) and continuous (industry) signals recorded



Example for transient seismic signatures caused by cars, trucks or motor-bikes.

Example for seismic signatures caused by machines, pumps etc.



ResultsVery high cultural noise in the urban environment (normally not used for seismic studiesNumerous transient (traffic) and continuous (industry) signals recorded„Natural“ signals not yet detected

Outlook and ongoing work Important new research field: automated identification and classification

of seismic signals in urban areas Diploma thesis on pattern recongnition with URS2 data started Lessons learnt will be incorporated into projects on monitoring of

geothermal sites like Landau (project proposal submitted).


Geology: EMR measurements

EMR profiles Staufen

EMR (natural electro-magnetic radiation):EM-pulses caused by formation and growing of microcracks as well as frictional sliding along cracks in stressed rocks



Combined results of campaigns 1,2:13.07.2010 14.09.2010



Result of campaign 3, 15.11.2009



Preliminary comparison of uplift determined by levelling and the EMR results



ResultsFairly well repeatability of the spatial EMR patternTemporal variations mainly in the number of EMR impulses Moderate EMR activity in the center, north of the town hallCentral EMR high enclosed by a ring of low emissionsHigh EMR values in the East and West directly adjacent to the geodetically determined uplift area Very low activity within the periphery

Outcome and ongoing work Relationship of the EMR results and the uplift process has to be studied

in more detail


Implications and new impulses

The STUB research programme strengthened the networking between the four involved institutes in two different facultiesThe use of innovative signals and innovative processing methodologies improves the knowledge and skills at KITData, results and newly recognized questions are incorporated into one doctoral thesis (geodesy) and one diploma thesis (geophysics)Lessons learnt will be incorporated into projects on monitoring of geothermal and oil production sites in the Rhine Graben Area Monitoring of the Landau geothermal power plant (project proposals submitted

to the ministries for environment in Mainz and Berlin) Monitoring of the Speyer oil field (pilot study supported by GDF SUEZ recently

completed; follow-on-project incl. FE-modelling, broad-band seismology, GNSS and X-band SAR interferometry envisaged)

The STUB contributes to the competence field „Geosphere and Risk Management“, to the KIT centres “Climate and Environment” and “Energy” as well as to the expertise of the “Landesforschungszentrum für Geothermie”


Staufen: borehole sites

Quelle: Sachstandsbericht zur Erkundung und Sanierung des Schadensfalls Staufen, Ruch & Wirsing, LGRB, 22.02.2010

Gip

skeu

per


Staufen: borehole sites

Oberer Gipsspiegel

Oberer Anhydritspiegel

Unterer AnhydritspiegelUnterer Gipsspiegel

28,6 m

61,5 m

126,1 m141,7 m


Staufen: local geological model

Data base: Analysis of drilling cuttings Shallow seismic investigation


Staufen: local geology and hydrology

4 confined aquifers detectedThe lower aquifers (Unterkeuper, Oberer Muschelkalk) are artesian; pressure head is 2 m above ground


Staufen: local geology and hydrology

Well no 7 was not correctly sealed and established a pathway for the artesian ground water from the lower aquifers. Between 62 m and 99 m, anhydrite absorbs water and transforms to gypsum, which goes along with an approx. 60% volume increase.


Appendix


SAR - Synthetic Aperture RadarParameter TerraSAR-X Höhe der Umlaufbahn: 514 km

Neigungswinkel gegen Äquator 97,4°

Antenne: Wa=0,7m, La=4,8 m

Trägerfrequenz f: 9,65 GHz

Wellenlänge l: 3,1 cm (X-Band)

Auflösung: 1 m, 3 m, 16 m

Bildbreite (Swath): 10km-100km

Bildlänge: 5km-1650km

Energieverbrauch: 2kW

Lebensdauer mindestens 5 Jahre

Gepulstes Radar Zweidimensionale Abbildung (Azimut x Range)


SAR-Interferometrie

noisedeformatmotoporef φφφφφφ ++++=

AtmosphärischePhase

Gemessene interferometrische Phase an einem Punkt

Referenz-Phase

TopographischePhase

Verschiebungs-Phase

Signalrauschen

δRVerschiebung

Hebung/Senkung

t = t2

t = t1


Lage der SAR-Szene


Installation von Corner-Reflektoren

PhasenreferenzVerknüpfungspunkt zum NivellementsUnterstützung und Validierung der Geokodierung


SAR Aufnahme 25.01.2009

Interferogramm

SAR Aufnahme 16.02.2009

-π +π


Modell einfallende Quellschicht

Modellparameter der Quellschicht

Einfallwinkel: 60°Länge: 1,4 kmTiefe: 50m-150mQuellung: 30cm

Bewegungenmax ∆vert : 18cmmax ∆horiz: 12cm


Modell einfallende QuellschichtHorizontale Verschiebung

Modellparameter der Quellschicht

Einfallwinkel: 60°Länge: 1,4 kmTiefe: 50m-150mQuellung: 30cm

Bewegungenmax ∆vert : 18cmmax ∆horiz: 12cm

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Assessing Active Lithospheric Deformations Around the