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Sismovalp – WP04 – Generic Alpine Valley Types

Caracterization of the geological history of our valley

QUESTIONNAIRE

Please fill the questionnaire inside this file. You can add lines wherever needed. The questionnaire should be filled as precisely as possible, with all available data.

The questionnaire should then be sent to corinne.lacave@resonance.ch before the end of year 2004.

1) Name of the valley: The Isere river valley in the Grenoble area Country: France


2) Geography / General information:




  • General orientation of the valley :

The valley is a furrow oriented NWN to SES, between the Chartreuse (to the North), the Belledone (to the East) and the Vercors (to the West) mountains.


  • General shape of the valley :

In the heart of the French Alps, the Isere cross-valley connects the Grenoble area to the Moirans plain: it constitutes an oblique diverticulum of Alpine furrow that is represented by the Gresivaudan plain.

The Gresivaudan plain and the plain of the Drac (river in the south of Grenoble) make a fork centred on Grenoble, named also the Grenoble Y.





  • Length and main width of the valley :

The limits of the valley we study are presented on the above map.

It measures approximately 5 km of width and 61 km of length.



  • Thickness of quaternary deposits (min to max) :

Max: 900 m

Min: a few meters on the edges of the valley



  • Elevation (above sea level) of the valley surface (upstream to downstream) :

Moirans : 198m Pontcharra : 256m Vif : 312m

Voiron : 290m Allevard : 475m Grenoble : 212m

3) History :


  • General geological evolution of the valley :

The filling of the valley in the Grenoble area is closely linked to the events of the recent Quaternary characterized by several glacial episodes.


1st cycle of the Riss glaciation:

During the Riss glaciation, there was an over-digging of the Gresivaudan valley and of the Grenoble area by alpine glaciers. Thus a first glacial trough was dug in the bedrock.


At the melt of glaciers, a lake occupied the Rissian valley and at the bottom of the lake, the lacustrine sediments were formed. This filling is characterized by the Eybens clays followed by the Bresson sands. The water level of the lake decreased gradually until to be completely filled by the upstream. The last deposits are the paludous sediments. A coarse sediment covered these paludous deposits in the northern Gresivaudan and gully the fine sands in the Grenoble area before the complete filling of the lake (the Champagnier gravels).
2nd cycle of the Würm glaciation:

A second trough was dug in the sediments of the post-rissian lake by the new glaciers of the Würm. The deep Würmian incision reached the bedrock and cleared allmost all the sediments of the Rissian glacial valley, what are locally observable on the edges of the trough.

The post-Würm was the last local lacustrine episode. The new trough was occupied by another main lake and was filled by lacustrine sediments: detrital clays type, followed by fine sands or silts. Finally the fluvial-like deposits, sands and gravels of the Drac and of the Isere rivers, chenalized into the lacustrine sediments. In the South of Grenoble, the coarse deposits of the Drac are predominant; while going to the North, the granulometric distribution smoothly decreases and the fine sediments of the Isere predominate.
There was a late fluvial dynamics that is expressed by channelling in a depression formed during the very warm Bölling period.

Scheme of the glacial trough’s filling (after Nicoud et al.)




  • Presence of a lake in the past: yes ; in the present: no

  • Over-digging : yes

Approximate depth (m): over-digging by the wurmian glaciers of 720 m at the borehole GMB1 (at Montbonnot)


  • Presence of glaciers in the past : yes ; number: 2




  • The glaciers of the Würm : they reached an elevation of 1050 m near Grenoble

(80 000 years before our era)

  • The glaciers of the Riss

(about 200 000 years before our era)


  • Historical seismic activity : yes





Séisme


Date

Max Intensity

(MSK)

Max Magnitude

(Richter scale)

Voreppe

12th January 1754


VI - VII




Bugey-Chautagne

1822


VII - VIII




Chamonix

29th April 1905


VII - VIII

5,7

Saint Clément

1935


VII - VIII




Sône

8 December 1938


VI




Saint Paul

1959


VII - VIII




Monteynard

22th November 1979





4,2

Rochefort-Samson

17th April 1984


V - VI

4 – 4,5

Corrençon

25th April 1962


VII - VIII

5 – 5,3

Epagny

25th April 1963

VII - VIII

5 – 5,5

15th July 1996


Grand Bornand

14th December 1994


VI - VII

5,1

Laffrey

23rd September 1997

VI

3,5

11th January 1999








Uriage

9th September 1992




2,3

3rd December 2000


Virieu

28th January 2004

IV

2,9

29th February 2004

4) Type of source data :



  • Boreholes: ~2000 superficial boreholes and one deep borehole

  • Gravimetry: 419 measurements

  • Seismic:

  • Seismic refraction profile (1) : Gresivaudan valley, length=6 km

  • Seismic reflection profile: Gresivaudan and Isere valley

  • Vertical and offset seismic profiles

  • Ambient vibrations: 300 and around 10 array measurements

  • Others : electric: about 118



  1. References :




  • Baconnais G., Doudoux B., Nicoud G. (1981) - Les dépôts quaternaires des principales vallées alpines et de l’avant-pays molassique de Haute-Savoie, France. Conséquences hydrogéologiques. C.R. Acad. Sci. Paris, t. 292, série II, pp 1313-1318.




  • Bard PY., Cartier S., Cotton F., Dietrich M., Hatzfeld D., Gueguen P. (2003) - Le risque sismique dans la région grenobloise, état des lieux en juillet 2003.




  • Bard, PY. and Riepl-Thomas J. (1999) - Wave propagation in complex geological structures and local effects on strong motion. Wave motion in earthquake engineering. E. Kausel and G. D. Manolis, WIT Press: pp 38-95.




  • Bellair P., Monjuvent G., Sarrot J. (1970) - Les argiles d’Eybens et le lac du Grésivaudan. C.R. Acad. Sci. Paris, t. 270, pp 7-10.




  • Benton, J., (2004). Etude géotechnique du bassin grenoblois : application au risque sismique, report : department geotechnics, Polytech’ Grenoble, 75 pp.




  • Bernath V. (1988) – La sédimentation iséroise de la cluse de Grenoble : étude in situ dans les terrassements du barrage usine EDF de St Egrève-Noyarey. Geologic university diploma, 101 pp.




  • Bocquet A. et J. (1969) - Nouvelles observations pour servir à l’étude du lac würmien du Grésivaudan. Rev. Géogr. Alp. Grenoble, 59, 3, pp 475-485.




  • Bonnefoy-Claudet, S., (2004) - Nature du bruit de fond sismique : implications pour les études des effets de site, PhD dissertation, Université Joseph Fourier, Grenoble, 216 pp.




  • Bourdier F. (1936) - Stratigraphie des alluvions quaternaires anté-würmiennes du Grésivaudan et de la vallée de Chambéry. C.R. Acad. Sci. Paris, t. 201, pp 977-979.




  • Bourdier F. (1962) - Le bassin du Rhône au Quaternaire. Géologie et Préhistoire. Ed. du CNRS, Paris, 2 vol.




  • Causse M. (2004) - Evaluation du mouvement sismique dans la cuvette grenobloise par la méthode des fonctions de Green empiriques, report : departmennt geotechnics, Polytech’ Grenoble, 80 pp.




  • Cornou C. (2002) – Traitement d’antenne et imagerie sismique dans l’agglomération grenobloise (Alpes françaises) : implication pour les effets de site. PhD dissertation. Grenoble, 260 pp.




  • Cornou, C., Bard PY. and Dietrich M. (2003) - Contribution of dense array analysis to basin edge induced waves identification and quantification. Application to Grenoble basin, French Alps (II). Bull Seism. Soc Am.




  • Cotton, F., Berge-Thierry C., Lemeille F., Pitarka A. et al. (1998) - Three-dimensionnal simulation of earthquakes in the Grenoble's basin (Western Alps). Second International symposium on the effects of surface geology, Yokohama, Japan, 1-3 December.




  • Cotton F., Bard P.Y., Berge C., Hatzfeld D. (1999) – Qu’est-ce qui fait vibrer Grenoble ?, la Recherche, pp 39-41.




  • Couturier B. (1974) – Contribution à l’étude géologique, hydrogéologique et géotechnique du bas Grésivaudan (Isère). PhD dissertation. Grenoble, 142 pp.




  • Coûteaux M. (1978) - Analyses polliniques d’un sédiment tardi-glaciaire à la Rivière (Isère). Evolution paléo-écologique du lac de Voreppe-Rovon. Bull. Ass.fr. Etude Quaternaire, 57, pp 171-178.




  • Debelmas J. (1995) - Le creusement du Grésivaudan : état actuel du problème. Géologie alpine, t. 71, pp 169-173.




  • Dietrich, M., Cornou C., Bordes C., Bard PY. et al. (2001) - Geophysical exploration for site effects assessment borehole measurements and vibroseis profiling in the Isere valley near Grenoble. EGS XXVI General Assembly, Nice, France.




  • Dietrich, M., Guiguet R. and Chaffard V. (1998) - Imagerie sismique des remplissages alluviaux dans la région de Grenoble. Rapport d'étude LGIT.




  • Fourneaux JC. (1976) – Les formations quaternaires de la vallée de l’Isère dans l’ombilic de Grenoble, géologie alpine.




  • Fourneaux JC. 1968 – Hydrogéologie du Grésivaudan. PhD dissertation. Grenoble, 98 pp.




  • Gidon M., Monjuvent G., Steinfatt E. (1969) - Sur la coordination des dépôts glaciaires de la Basse Isère, de la Bièvre et du Rhône (environs de Voiron, Isère). C.R. Acad. Sci. Paris, t. 268, pp 1464-1467.




  • Gignoux M. (1944) - L’épaisseur des dépôts quaternaires dans la plaine de Grenoble. Extrait C.R. Soc. géol. Fr., n° 8, pp 77-78.




  • Gueguen, P., C. Cornou, P. Y. Bard and F. Dunand (2003) - Origine des bouffées haute énergie observées sur le bassin de Grenoble. VIth National Seminary AFPS, Ecole Polytechnique Palaiseau France.




  • Hannss C. (1984) - La constitution des plaines alluviales et leurs rebords dans la vallée de l’Isère, entre l’embouchure de l’Arc et le bassin de Moirans. Rev. Géogr. alp. Grenoble, 72, pp 2/3/4, 439-456.




  • Lebrun, B., Hatzfeld D., and Bard PY. (2001) - A site effect study in urban area: experimental results in Grenoble (France), Pageoph. 158, pp 2543-2557.




  • Lebrun B. (1997) – Les effets de site : étude expérimentale et simulation de trois configurations. PhD dissertation. Grenoble, 208 pp.




  • Lemeille, F., Bard PY., Cotton F. and Hatzfeld D. (2000) - Effet de site sur les ondes sismiques : forage de Montbonnot (Isère) 1. Organisation du projet. Session E4, RST, 17-20 april.




  • Lemeille, F. (2002) - Forage de Montbonnot 2 (GMB 2), Organisation et suivi géologique du forage, IRSN internal report, 02-55, 15 pp.




  • Margalhan-Ferrat H. (1975) – Contribution à l’étude géologique, hydrogéologique, géotechnique de la cluse de l’Isère. PhD dissertation. Grenoble, 100 pp




  • Michel R., Rothe J. (1959) - Sur la nature de l’épaisseur des alluvions quaternaires dans le bassin de Vizille (vallée de la Romanche, Isère). C.R. Acad. Sci. Paris, t. 246, pp 1888-1890.




  • Monjuvent G., Uselle J.P. (1973) - Interprétation des argiles d’Eybens d’après la sédimentologie du sondage INQUA 1969. Bull. Ass. fr. Etude Quaternaire, t 2, pp 103-128.




  • Moret L. (1955) - Données nouvelles sur l’âge absolu et l’origine des argiles d’Eybens près de Grenoble. Trav. Lab. Géol. Univ. Grenoble, t. 32, pp 11-14.




  • Nicoud G., G. Royer, C. Corbin, F. Lemeille, A. Paillet. 2002 – Creusement et remplissage de la vallée de l’Isère au Quaternaire récent, Géologie de la France n°4, pp 39-49




  • Nicoud, G., Royer G., Corbin JC., Lemeille F., and Paillet A. (2002) - Glacial erosion and infilling of the Isère Valley during the recent Quaternary, Géologie de la France, n°4, pp 39-49.




  • Nicoud G., Monjuvent G., Maillet-Guy G. (1987) - Contrôle du comblement quaternaire des vallées alpines du Nord par la dynamique lacustre. Géologie alpine, Mém. H.S. n°19, pp 457-468.




  • Piraud V. (1924) - Le sous-sol de la vallée du Grésivaudan. Bull. Soc. Sci. Isère, t. 45, pp 405-406.




  • Scherbaum, F., Riepl J., Bettig B., Ohrnberger M., Cornou C., Cotton F., Bard PY. (1999) - Dense array measurements of ambient vibrations in the Grenoble basin to study local site effects, AGU Fall meeting, San Francisco, December 1999.




  • Tadenuma S. (2003) - Etude des formations superficielles du basin grenoblois, report : department geotechnics, ISTG (Polytech’Grenoble), 71 pp main volume.




  • Talloni SP. (1978) – Contribution à l’étude géotechnique du sillon subalpin entre Grenoble et Vif. PhD dissertation. Grenoble, 192 pp.




  • Vallon M. 2000 – Estimation de l’épaisseur d’alluvions quaternaires dans la cuvette grenobloise par inversion des anomalies gravimétriques. Final Report of CNRS and IPSN, 38 pp.




  • Vallon, M., Bonnaffé F., Janson X., Mieulet MC. et al. (1996) - Carte des isopaches du remplissage quaternaire de la cuvette grenobloise déduite des anomalies gravimétriques. Internal report of Laboratoire de Glaciologie et de Géophysique.

5) Human activity:




  • Urbanised surface : about 12145 km²

  • Industrial activity : yes

Type: Grenoble urban area has a great industrial activity and a sharp expertise in innovative technologies, mainly organised around three poles: the Information technology pole, Biotechnology pole, and New technologies.

The mechanical engineering industry encompassed a series of activities which include capital goods - the majority of the sector - industrial metal-working services and metal products.

6) Geology:


6.1) Bedrock:

  • Bedrock type (both sides) :

On the both sides, there is black limestone of the Bajocien inferior period.

  • Average slope (both sides) :

  • In the WN, average slope : about 19°

  • In the EN, average slope : about 15°

  • In the south, the average slope is smoother.

  • Outcrop of bedrock inside the valley : no

6.2) Quaternary deposits (valley filling and lateral deposits):



  • Description of the quaternary deposits constitutive materials :

These deposits are settled after the glaciation of the Würm.


  • alluvial :

Those are coarse alluvium (sands and gravels) with interbedded layers with large granulometric heterogeneity; their thicknesses are about 10 to 30 m.

The coarse fraction represented 75 and 85% of the series. Sands, silts and clays are represented like lenses inserted in coarse elements.

It is due to the differential influences of the Drac River and of Isere River: the alluvium of the Drac is coarser whereas the alluvium of the Isere is finer.


  • lacustrine :

Those are fine sands or silts. Their average thicknesses are of 15 m but can reach more than 20 m or can be non-existent.

They are constituted of fine sands more or less clayey and especially developed in the North of Grenoble.



  • torrential :

Those are compact clays resulted from the filling of the last post-Würmian lake. This homogeneous layer could reach several hundred meters of thickness.

Those clays are more or less compact, colour blue-grey, finely bedded and similar to the Eybens clay less competent.



  • morainic :

According to their localizations, we have either rocks or stones in clayey matrix, or linear deposits with heterogeneous granulometric distribution.

Age

(before our era)

Era

Period

Glaciation

Geological formations




1000

THE

QUATERNARY



Holocene

Post-glaciation

Sands and gravels


Observable in the whole Isere valley

Fine sands or silts


Compact clay


16000


Pleistocene superior

Würm

Moraine


No trace or observable in special point

( for example: on the glacial trough’s edges)



80000

Interglaciation Riss-Würm

Bresson sands


Eybens clay


120000

Middle Pleistocene

Riss

Moraine



  • General dip direction of the deposits : horizontal

  • Mud flow channel: yes

  • Fan delta: no

  • Lacustrine delta: yes

  • Marsh / peat bog : yes

  • Collapse zone : yes

  • Landslide, creeping : yes

  • Rockfall activity : yes

  • Scree deposits on the sides : yes

  • Lateral water stream, torrent, secondary valley : no

  • Artificial fills : no



  1. Attached documents:

Appendix A: Geological of the Isere valley


Appendix B: Synthetic geological map of the Grenoble area (from C. Kerchove)
Appendix C: Maximum extension of the würmian glaciation surrounding Grenoble

(from Montjuvent et al., 1987)


Appendix D: First proglacial lakes during the würmian deglaciation (from Montjuvent et al., 1987)
Appendix E: Würmian glacial retreat lakes (from Montjuvent et al., 1987)
Appendix F: Alluvial filling into the downstream area of the Isere valley (from Nicoud et al., 2002)
Appendix G: Cut-and-fill of the würmian glacial through into the rissian glacial through: synthetic cross

section at the vicinity of Eybens (from Nicoud et al., 2002


Appendix H: Isopachs of quaternary sediments, gravimetric stations (triangle) and curves of bedrock’s

equal depth (from M. Vallon)


Appendix I: Localization of boreholes in the Grenoble basin (from S. Tadenuma, 2003)
Appendix J: Example of penetrometric test (Montbonnot borehole)
Appendix K: Example of pressiometric test (Montbonnot borehole)
Appendix L: Simplified lithlogie of GMB 1 – Montbonnot log (from Nicoud et al., 2002)
Appendix M: Localization of the cross-sections (from S. Tadenuma, 2003)
Appendix N: Localization of ambient vibration measures (from J. Banton, 2004)
Appendix O: Gravimetric measures in the Grenoble area (from M. Vallon)


Appendix A
Geological map of the valley (with structural info)

Geologic maps of Vif (1967), of Vizille (1972), of Domène (2000), and of Grenoble (1978)



scale 1/50000. Ed. BRGM









A
Synthetic geological map of the Grenoble area (from C. Kerchove)
ppendix B


Appendix C



Appendix D


Appendix E



Appendix F & G


Appendix H

Isopachs of quaternary sediments, gravimetric stations (triangle)

and curves of bedrock’s equal depth

(from M. Vallon)

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