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Geophysics - Instrumentation - Environmental studies
Stratagem974 is a geophysical company located in Reunion Island. Diversified
activity and solid skills allow us to find solutions to civil engineering and
environmental issues thanks to non destructive methods, high technology devices
and high qualified staff. Were also able to work in difficult access sites.
Our specialities in applied Geophysics
Electrical Resistivity Tomography (ERT) 2D or 3D: water resources, mining
prospecting, civil engineering (lava tubes detection, sediments structure, substratum), with
an investigation from some meters to over 200 meters depth.
Fig 3 : hydrogeological / mining application of ERT survey
62 bvd du Chaudron97490 Sainte-ClotildeReunion IslandTl/fax : (+262) 262 21 84 69Cell : (+262) 692 26 60 62 / 692 36 96 50Mail : contact@stratagem974.com
Fig 1 : ABEM SAS4000 and multiplexer,powered by 12 V battery
Fig 2 : acquisition profile on the field
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Fig 4 : geothermal prospecting
Fig 5 : lava tubes and cavities detection
Seismic reflexion / refraction: allows to visualize geological structure from seismicwaves echo created by a source (explosion, hammer hit or vibrating truck).
Applications :civil engineering, mining deposits, geological risks,
We are able to achieve submarineelectrical resistivity studies in order to :
- identify sedimentary layers structure
- detect fresh water resurgence
Fig 6: electrical tomographydevice for lagoon operation
64 electrodes device
Fig 7: seismic refraction profile
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Cross-hole and down-hole : recording of P and S waves velocity between drills and
ground characterization. Determination of Shear modulus G, Youngs modulus E and Bulk
modulus K.
Fig 8 : cross hole device : source (a), recever (b) and determination of modulus
a b
Electromagnetic induction:
high tension lines detection, electric and
telephonic cables, underground or inside
buildings. Unconnected cables can also bedetected.
Fig 9 : watercourse detection
Ground Penetrating Radar (GPR) :
buried pipes and cables detection (electrical,
telephonic), watercourses, cavity localisation,
GPR has others applications in several fields:
- assessment of reinforced concretecorrosion in term of corrosion probability inprospected areas.
- archaeology and palaeontologyapplication in order to locate signs of buriedhuman activities, gravestone, fossils (dinosaursand giant birds eggs,)
Fig 10 : GPR campaign
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cutting
Self Potential (SP) : measurement of
natural potential differences between a
reference and several points in order to draft a
site cartography.
Applications: contaminated soils assessment
(pollution spreading), corrosion potential
cartography of reinforced concrete structure,
leak detection on a dam,
Fig 12 : SP cartography in a contaminated site
Fig 11: buried pipe detection by GPR
Deformations monitoring of civil engineering
structure (bridge, dam, tunnel) by a network of electronic
nivels (accuracy = 0,001 mrad) and differential GPS
Fig 13 : electronic Nivel (Leica Geosystems)
Fig 14 : real time deformations monitoringof abutments of a 300 meters-long bridge
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Stratagem974 is also specialized in concrete structure assessment thanks to the
combination of several geophysical methods:
- woven-wire and corrosion detection in reinforced concrete by GPR- corrosion cartography by spontaneous potential
- deformations monitoring- geological studies by ERT...
Vibrations monitoring(building sites, airport,) by measuring and recording groundmovement velocity with geophones. It also can be used to detect water leak in a pipe.
Fig 16 : vibrations monitoring
Fig 15 : reinforced concrete structure bygeoradar 2GHz
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Soil or concrete sampling
Video inspection by micro-camera: civil engineering structures, drill hole, piping,tank, Investigation until 200 m-long.
Gravimetric anomalies measurement. Applications: geothermal prospecting,
underground cavities detection
Soil gas detection: Radon, CO2.Applications: volcanic and health risks assessment.
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Fig 18 : lava tubedetection withgravimetric method
Fig 19 : measurement of radon emitted by the ground
Fig 17 : concrete samplingcampaign for a pollution diagnosis
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Hydrology - Hydrogeology - Geochemistry
Instrumentation in hydrology and hydrogeology (preliminary studies, turn-key
systems supplying and installation):- multi-parameters meteorological measurement (pluviometry, temperature, atmosphericpressure, humidity, wind velocity, sunshine.)
- river data acquisition (flow, conductivity, temperature, pH)
- drill monitoring (water level, conductivity, temperature)
- sampling
Applications : water table and watershed studies, pollution monitoring, water balance,
Partnership with Geosciences Laboratory of Reunion University
Water analysis by ion chromatography DIONEX ICS 1000 :- major cations : magnesium, sodium, potassium, calcium- major anions: fluorine, chlorine, nitrates, sulphates
Rock and water analysis by XRF (Panalytical) :- total rock- heavy metals (mercury, lead, cadmium, cover, arsenic, or, nickel, zinc, cobalt,manganese)- others elements according to Mendeleev table
Rock textural analysis: preparation of rocks samples for microscopic observation andanalysis
Fig 20 : ratio rain/flow
Fig 21 : drills and sensors (conductivity,
temperature, pressure,)
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Our main references
o Conseil Gnral Runion (1993-2003) : Hydro-Fournaise program
- Establishment and monitoring of data acquisitions stations in fields of
hydrology and hydrogeology.- Geophysical measurements program: SP, TDEM, Electrical, VLF et AMT at
the Reunion
o French Cooperation Ministry (1996-1997) : Programme FAC (Fond dAide laCoopration) to develop Mauritius water resources (TDEM et CSAMT)
o Rgion Runion (2001-2007) : Geothermic program : (gravimetry, TDEM,CSAMT, SP, ERT)
o Gosciences Runion (1996-2008) : ERT, SP, AMT, TDEM
o Internationalcooperation (UNDP Comoros Island) : geophysical campaigns on
Karthala volcano (GPR, PS, GPS diffrentiel, Gaz du sol),
o Groupe Taylor&Smith (Mauritius, 2007) : textural study of rocks samples,
o UNO (2007-2008) PNUD (Programme des Nations Unies pour le Dveloppement) Reduction Risk & Disaster geophysical instrumentation of Karthala,
o Laboratory CREGUR (UR), Reunion (2007) : multi-parameters sensorsinstallation
o VINCIGroup (2007-2008) : pipes and cables detection with georadar
o SOGEA (2008) : cavities detection by electrical tomography
o DDE Runion/SGT (2008) : preliminary geophysical study for a bridge buildingo INGV (2008) : electrical tomography, SP,
o Rgion Runion (2008-2009) : Tram-Train project, GPR
o French Defence Ministry (2008-2009) : GPR, soil pollution diagnosis
o SHLMR (2008-2009) : cavities detection by electrical tomography
o Contaminated sites monitoring (2008) : confidential
o Conseil Gnral Runion (2008-2009) : bridge deformations monitoring bygeodesic sensor (confidential)
o French electrical company (EDF) (2009) : cross-hole campaign
o BRGM (2009) : hydrogeological characterization of a river by electrical andseismic measurements.
o ARUP SIGMA (Mauritius, 2009) : ERT
STRATAGEM974
62 Bvd du Chaudron 97490 Ste Clotilde REUNION island
Tel/fax : (262)262218469 Cell : (262)692266062
mail : contact@stratagem974.com