Hardrock Seismic Exploration

276 Pages·2003·29.98 MB·English

by  David W. Eaton, David W. Eaton, Bernd Milkereit, Matthew H. Salisbury

Hardrock Seismic
Exploration
Edited by David W. Eaton, Bernd Milkereit,
and Matthew H. Salisbury
SeriesE ditor.'S tephend . Hill
GeophysicaDl evelopmentsS eriesN o. 10
Societyo f ExplorationG eophysicists
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SOCIETY OF EXPLORATION GEOPHYSICISTS
Library of CongressC ataloging-in-PublicatioDn ata
Hardrock seismice xploration/ editedb y David W. Eaton,B ernd Milkereit, and Matthew H. Salisbury.
p. cm.- (Geophysicadl evelopmentss eries; no. 10)
Includesb ibliographicarl eferences.
ISBN 1-56080-114-X (alk. paper)
1. Seismicp rospecting. I. Eaton,D avid W., 1962- II. Milkereit, Bernd, 1955- III. SalisburyM, atthew H.
(Matthew Harold), 1943- IV. Geophysicadl evelopmenst eries;v . 10
TN269.8.H37 2003
62T. 1592-dc21 2003043442
ISBN 0-931830-41-9 (Series)
ISBN 1-56080-114-X (Volume)
Societyo f ExplorationG eophysicists
P.O. Box 702740
Tulsa, OK 74170-2740
¸ 2003 Societyo f ExplorationG eophysicists
All rightsr eservedT. his booko r partsh ereofm ay not be reproducedin any form withoutp ermissionin writing from
the publisher.
Printed in the United States of America
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Acknowledgment
This projectw as supportedb y the CanadianS ocietyo f ExplorationG eophysicists
throught he CSEG Superfunda, nd the Natural Sciencesa nd EngineeringR esearch
Council of Canada.E ileen Blackmoreh elpedt o preparea nd compilet he manu-
scripta nd figures.
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Contents
Introduction
HardrockS eismicE xplorationM: atureT echnologieAsd aptedt o NewE xplorationT argets
D. Eaton, B. Milkereit, and M. Salisbury
Part I: PhysicaRl ockP ropertiesa nd GeophysicaLlo gging
1. The AcousticP ropertieso f Oresa nd Host Rocksi n Hardrock Terranes
M. H. SalisburyC, . W.H arvey,a ndL . Matthews
2. GeophysicLaol ggingfo r ElasticP ropertieisn Hard Rock:A Tutorial 2O
D. R. SchmittC, . J. MwenifumboK,. A. Pfiug,a ndL L. Meglis
Part II' SimulatingE lasticW avesi n the Hardrock Environment 43
3. Influenceo f Morphologayn dS urfaceR oughnesosn t heS eismiRc esponsoef MassiveS ulfides,
Based on Elastic-Wave Kirchhoff Modeling 45
G. J Clarke and D. W. Eaton
4. 3D Modelingo f Seismic-WaPvreo pagatioUns ingC ompleEx lasticS creenws,i thA pplication
to Mineral Exploration 59
R. W. Hobbs
5. ElasticS eismic-WavSec atteringfr omM assiveS ulfideO rebodiesO: n theR oleo f Composition
and Shape 7O
T. Bohlen, C. M(cid:127)iller, and B. Milkereit
Part III: RegionalS eismicR econnaissancSet udies 91
6. Experiencefrso mS hallowR (cid:127)flectionS eismicosv erG raniticR ocksin Sweden 93
C. Juhlin and H. Palm
7. SeismiEc xplorationo f theM anitouwadgGer eenstonBee lt,O ntario'A CaseH istory 110
B. Roberts,E . Zalesla'G, . Perron,E . (cid:127)4dam,L . Petrie,a nd M. Salisbury
8. Seismic-ReflectiIomna gingo f the Environmenatr oundt heM ountI sa OrebodiesN, orthern
Australia: A Case Study 127
B. J. Drummond(cid:127)4, .J . Owen,J . C. JacksonB, . R. Golebya, nd S. N. Sheard
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vi Contents
Part IV: 2D Seismic Imaging of Mineral Deposits 139
9. SeismicI maging of Preciousa nd Base-Metal Depositsi n Southern Africa 141
F. StevensonR, . M. A. Higgs, and R. d Durrheim
10. Using Surface-SeismicR eflection to Profile a Massive Sulfide Deposit at Mount Morgan, Australia 157
B. d Evans, M. Urosevic, and A. Taube
11. A Comparison of 2D Seismic Lines Shot over the Ansil and Bell Allard Mines in the Abitibi
Greenstone Belt 164
A. d Calvert, G. Perron, and Y. Li
Part V: Downhole SeismicI maging 179
12. Vertical SeismicP rofiling at the Bell Allard Orebody, Matagami, Qu6bec 181
E. Adam, T. Bohlen, and B. Milkereit
13. Application of Downhole SeismicI maging to Map Near-Vertical Structures: Norm6tal (Abitibi
Greenstone Belt), Qu6bec 194
G. Perron, D. W. Eaton, B. Elliot, and D. Schmitt
14. Multiazimuth VSP for Rock Characterization of Deep Nuclear Waste Disposal Sites in Finland 207
C. Cosma, P. Heik]a'nen, and d Kes]a'nen
Part Vl' 3D SeismicI maging 227
15. 3D SeismicI maging for VMS Deposit Exploration, Matagami, Quebec 229
E. Adam, G. Perron, G. Arnold, L. Matthews, and B. Milkereit
16. A Review of 16 Years of Hardrock Seismicso n the Kaapvaal Craton 247
C. C. Pretorius,M . R. Muller, M. Larroque,a nd C. Willa'ns
Index 269
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Introduction
Hardrock Seismic Exploration: Mature Technologies
Adapted to New Exploration Targets
D. Eaton, B. Milkereit, and M. Salisbury
INTRODUCTION enhancede lectricalc onductivityc, hargeabilityo, r mag-
netization, in order to pinpoint potential targets for
... the bulwarko f a continenth ere laid bare, with itsp roper
drilling. Althoughw ell suitedt o shallow( <500 m) ex-
soil swepto ff,' the elementalb edrock,w ith its hiddenr iches
and its answerst o great mysteries. plorationp roblemsa ndr eadilya daptable(i n somec ases)
B. Moon, The Canadian Shield to airborneo r satelliter emotes ensinga pplicationst,h ese
classical" hardrock"t echniquesa re constrainedb y in-
Hardrock environmentso ccur on every continent. escapableli mitationst o their sensitivitya nd resolving
From modern mountain belts to ancient shield ar- powerw ith increasingd epth.T hesel imitationsa rea fun-
eas, this geological setting is dominatedb y diverse damentacl onsequencoef theu nderlyingp hysicso f these
and often stronglyd eformed assemblageso f igneous methods,w hich ultimatelyr esto n Laplace'se quationo r
and metamorphicr ocks. Suche nvironmentsa re gener- the principleso f diffusion.W hile thesem ethodsh ave
ally far removedf rom petroliferouss edimentaryb asins been sufficient to meet the needs of industrialized nations
where seismice xplorationi s commonplace--andv irtu- in thep ast,r ecentd eclinesi n basem etalr eservesc, aused
ally terra incognitat o the vast majority of exploration by the depletiono f known shallowd epositsa nd declin-
seismologistsY.e t, theser egionsh osta substantiaflr ac- ing rateso f discoveryf or new depositsw, ill requiret he
tion of the planer'sm ineralw ealth,p rovidea n unparal- useo f deepere xporationm ethods( e.g., Debicki, 1996).
leled geologicarl ecordf or mosto f Earth history,a nd,i n Seismicm ethodso ffer one possibles olution.
the caseo f stables hieldr egions,a re the focuso f various For more than 70 years, seismic-reflectionm ethods
nationalp rogramsto find long-terms torages olutionsfo r have been usedw ith great successto explores edimen-
dangerousm an-madew aste.A s an economicf orce,t he tary basinsf or deep-seatedh ydrocarbonr eservoirs,b y
impacto f mining alonei s significantF. or example,t he mappings tratigraphica nd structurald iscontinuitiesin
combinedv alue of worldwide gold, coppera nd nickel the subsurfaceW. ith the exceptiono f coal exploration,
productiona mountedt o an estimated$ 57.9 billion in however,s eismicm ethodsh ave had relatively limited
1999 (Table 1), representinga lmost 10% of the value use in mineral explorationa nd other hardrocka pplica-
of worldwidec rudeo il productiond uringt he samep e- tions. This has been due, in part, to the relativelyh igh
hod. Explorationa ndr esearcha ctivitiesr elatedt o these cost of seismicm ethods( a major deterrentt o compre-
themesr ely upong eophysicatle chniquesto providec rit- hensivef ield testing),c oupledw ith a lack of a detailed
ical subsurfacein formationa nd 3D mappingc apabili- understandingo f the relevantp hysical-rockp roperties.
ties.I mprovedc, ost-effectivgee ophysicatel chniqueasr e In the 1980s two key caseh istoriese stablishedth e po-
neededt o map and exploret he deep structureo f these tential of seismicsa s a mapping tool in the hardrock
regions. environment.G reen and Mair (1983) presenteds eis-
Classicaln onseismicg eophysicaml ethods,i ncluding mic imageso f complexf ractures ystemsa t a radioactive
electromagnetic,i nduced-polarizationp, otential-field, wasted isposasl itei n the CanadianS hield.S ubsequently,
and, more recently,r adiometrict echniquesh, ave been Pretoriuse t al. (1989) demonstratetdh eu sefulnesso f an
theb ackboneo f minerale xplorationfo r decadesa ndt hus integrateds eismica ndp etrophysicaal pproachto image
havea moreo bviousa ssociationf,o r mostg eophysicists, key geologicals tructuresfo r mineral explorationi n the
with hardrocks ettings.T hese methodse xploit anoma- Witwatersrand Basin, South Africa. These case histo-
lous physicalp ropertieso f mineral deposits,s uch as ries, togetherw ith large-scalec rustals eismic-profiling
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2 Introduction
Table 1. Estimated value of worldwide production of selectedm inerals and crude
oil in 1999, in $U.S.
Commodity Net GlobalP roduction Unit Unit value Totalv alue( billions$ )
Gold1 2540 tonnes $9,002,196 22.87
Nickel2 1120000 tonnes $7,488 8.39
Coppe3r 12600000 tonnes $2,114 26.64
Oiln 29747.5 Mb/c $20,000,000 594.95
1 Basedo nA meyE, . B. (2001)
2 Basedo nK uckE, H. (2001)
3 Basedo nE delsteinD,. L. (2001)
4 Basedo nC hang(1 999)a ndP etze(t1 999)
initiatives, sucha s COCORP (U.S.A.), LITHOPROBE overviewo f the relevantl aboratorya ndf ield techniques,
(Canada),D EKORP (Germany),E CORS (France)a nd tutorials on physical-rock properties and borehole
AGSO (Australia), have serveda s catalystsf or numer- loggingt echniquesa rep resentedin Part I of the book.
ous integratedh ardrocks eismici nvestigationsd uring In the first paper, Salisburye t al. review laboratory
the 1990s. These largely independentr esearche fforts velocity and density measurementsp erformed under
aroundt he globeh avee stablishedth e potentialo f seis- insitup ressures(2 00 MPa) on a wide variety of rocks,
mic methodsto provides tructurailm agesf or deepm in- includingb oreholes ampleso f oresa ndh ostr ocksf rom
eral explorationr, adioactivew asted isposasl itee valua- mining camps. S-wave velocities of ores, critical for
tion and geotechnicailn vestigations. a completeu nderstandingo f elastic-wavei nteractions
This specialp ublicationb rings togetherr epresenta- with ore depositsa, re alsop resentedfo r the first time in
tive contributions,f rom aroundt he world, that document this paper. Salisburye t al. showt hat elasticp roperties
the growingi mportanceo f seismic-exploratiomn ethods and acoustici mpedanceso f massives ulfidesa re signifi-
in the hardrocke nvironmentT. hrougha compilationo f cantlyd ifferentf rom thoseo f mostc ommonh ostr ocks.
tutorialsa nd caseh istoriesi llustratingi nnovativea ppli- This implies that ore depositss houldb e detectablea s
cationso f maturet echnologiesto new targets,t his book reflectorso r scatterersp, rovidedt hat geometricalc on-
providesa n up-to-date,a uthoritativer eferenced escrib- ditionsf or imaging( size and deptho f the deposit)a re
ing how seismicd ata acquisitionp, rocessinga nd inter- met. Severalc onsiderationtsh at complicatet he analysis
pretationc an be effectivelyt ailoredf or use in hardrock of reflectivity,s ucha s seismica nisotropya nd orebody
applications.O ur objectivei s to increasea warenesso f morphologya, rea lsor eviewedI.n then extt utorialp aper,
hardrocke xplorationw ithin the traditionals eismici n- Schmitt et al. summarizet he petrophysicso f wireline
dustry, as well as to provide the basis for a broader logginga pplicationsin the hardrocke nvironmentw, ith
appreciationo f seismicm ethodsw ithin the mineral- illustrative examples.T hey note that laboratory mea-
explorationa ndg eotechnical-engineerincgo mmunities. surementsfr om samplesm ay not be fully representative
of the physical propertieso f ore depositsa t seismic
wavelengths calesb, ecauseo f the presenceo f fractures,
OVERVIEW
formationd amagea, nda mbients tressc onditionsC. on-
Seismic-explorationm ethodsi lluminate the subsur- sequentlyf,u ll-waveforms onica ndd ensityl ogsp rovide
face using elastic( P and S) waves.T he signalso f in- essentiailn -situc onstraintso n elasticp ropertiesA. prac-
terest arise from reflection, refraction and scattering titioner must be aware, however,o f other effects that can
of thesew avesa t lithologica nd structurabl oundaries, influencet he final interpretationw ireline loggingd ata.
where abrupt changesi n elasticr ock propertieso ccur. Despitet he diversitya nd sophisticationo f available
A soundg eologicali nterpretationo f theses eismics ig- tools for seismicm odeling, wavefield simulationr e-
nalsr equiresa completeu nderstandinogf the pertinent mainsa significanct hallengein the hardrocks ettingd ue
rock properties( e.g., P-wave velocity, S-wavev elocity to the need for 3D modelst o accountf or out-of-plane
and density)a nd how they are relatedt o specificr ock scatteringe ffects,t he oftenc omplexm orphologyo f tar-
types, as well as how they are influencedb y pressure, get features,a nd the stochasticn ature of background
temperature,a nd pore-fluid conditions.T o provide an heterogeneityT. hree papersa re containedin the Part II
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Hardrock seismice xploration: Mature technologiesa dapted to new exploration targets 3
of this volume, describingd ifferentn umericalm ethods geologicalf eaturest o depthso f up to 2 km, primarily
that can be used to simulate wavefields in a hardrock for high-level nuclear waste disposals tudies.T he au-
environment.T he methodst radeoffv arying degreeso f thorsp rovidea clear and conciseo verviewo f the neces-
approximationa gainstc omputationael fficiency.C larke sary modificationsto tailor data processingte chniques
and Eaton introduce a new, fast elastic Kirchhoff tech- to hardrockt erranes.I n addition,t hey showt hat fracture
niquet hatc alculatess eismicw avefieldsb y computinga n zonesi n graniticr ocksc an sometimesb e differentiated
integralo vert he surfaceo f an elastici nclusion( sucha s from dolerite( diabase)s ills basedo n the polarity of the
an ore deposit).T hey apply this techniquet o investigate reflectedw aves,a nd that it is possiblet o image features
the influenceo f inclusions hapea nd surfacer oughness that dip up to 60-70 ø using surfaces eismic-reflection
on the scattereds ignals.C larke and Eaton find that flat- methods.
tened inclusionss catters ignalsp referentiallyp erpen- The nextp aper,b y Robertse t al., describesa multidis-
dicular to the long axis of the body, and that surface ciplinary studyi n the Manitouwadgeg reenstoneb elt of
roughnessc an causea n objectt o appears eismicallyu n- northernO ntario,w here recentm ine closuresp rovidea
detectable,e ven in the presenceo f a large impedance strongm otivationf or developingg eophysicatle chniques
contrast. that can guide deep drilling programs.T his area is the
In the following article, Hobbs appliest he recently mosth ighlyd eformeda ndm etamorphosehda rdrocks et-
developedc omplex elastic-screenm ethod to investi- ting presentedin thisv olume,a ndi nitial detailedg eolog-
gate scatteringc haracteristicos f a massives ulfideo re- ical mappingw asn ecessaryto generatea workings truc-
body containedw ithin a volcanic sequencew ith ran- tural model. Follow-on studiesi ncluded physical rock
dom velocity fluctuationsB. y comparingt he computed propertya nd boreholes urveys,w hich providedc ritical
responsef or 3D surface-reflections eismic data and acousticp ropertyd ata for the main lithologicalu nits.I n
3-component vertical-seismic-profilingd ata, Hobbs addition, 3D forward modeling provided a framework
showst hat imagingo f smallo re depositsin a stochastic for surveyd esigna ndi nterpretationA. programo f three
mediumm ay be problematicu sing surfacer ecordings. intersectings eismicp rofiles was acquiredt o delineate
On the other hand,h e finds that P- and S-wave energy key marker horizons.R oberts et al. show that seismic
recordedb y vertical seismicp rofilesc anb e usedr eliably geometriesfr om thisp rograma re consistenwt ith the re-
to detects uchf eaturesa t rangeso f over 1 km. gional structuralm odel. Severald eepb oreholes,d rilled
In the next paper,B ohlen et al. describet he first ap- to testh igh-amplitudes eismica nomalies,c onfirmedt he
plicationo f 3D viscoelasticfi nite-differencem ethodst o interpretationo f the main contactsb ut did not encounter
forward modeling problemsi n a hardrock setting.B y massive sulfides.
modelingt he full wave equation,t his approachr eveals Drummonde t al. invoket he mineral-systemc oncept,
thatl argeo re depositsle adt o a stronga ndc omplexs cat- which recognizest hat ore depositionr equires a fluid
tering responseth at is dominatedb y shear-wavee vents. source,a migrationp athway,a nd a trap as a framework
They find that the directivity imposedb y the shapeo f for seismici nterpretationi n mineral exploration.T his
an ore depositi s a first-orderc haracteristico f the scat- innovativea pproachw as applied to investigates truc-
teredw avefield,a sa consequencoef amplitudef ocusing tures that controlled the location of silver-lead-zinc and
phenomena.C ompositione ffects,h owever,p rovide an copper orebodiesa t the Mount Isa mine in northern
importants econdarys ignal, sincet he FD modeling in- Australia.T he ParooF ault, a reflectivem arker that rep-
dicatest hat the first arrival phaser eversalso ccura lmost resents the structural lower limit of mineralization in the
irrespectiveo f shapeT. his potentialt o infer composition area,w as the primary targetf or seismici magingr ather
fromp hase-reversaolb servationiss encouragings, incei t that the mineralizationi tself. Detailed mappingo f this
supportsth ep ossibilityo f distinguishings catteringfr om fault providesi mportant structuralc onstraintsf or ex-
oresf rom other typeso f scatteringth at can complicate ploration. Furthermore,t he alterationh alos aroundt he
seismic records in hardrock environments. copper orebodiess eem to be broad enought o form a
PartI II of thisb ookd ealsw ith regionals eismicr econ- likely target.
naissance studies in hardrock environments. In the first In Part IV, Stevenson et al. document a diverse set
papero f this section,J uhlina ndP alm summarizer esults of successful case histories in which seismic methods
from five site investigationsin Swedenw here seismic- have been used for precious- and base-metale xplo-
reflectionp rofiles have been used to image important ration in hardrock settingso f southernA frica. In the
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4 Introduction
WitwatersrandB asin, reflection seismologyh as been closert o thet argetz one.A dam et al. presenrt esultsf rom
instrumentali n severalr ecent major gold discoveries, two vertical seismicp rofile (VSP) surveysa cquiredi n
by allowingA rcheanm arker horizonst o be mappeda t the vicinity of a 1-km deepv olcanogenicm assives ulfide
depth and thus enablingt he position of gold-bearing depositi n northwesternQ uebec.I n the caseo f a borehole
reefs to be inferred. High-resolutionv ibroseism ethods intersectingth e deposit,s trongs catteredP - and S-waves
have also been used in the BushveldC omplex, a giant were observedI.n the caseo f a nearbyn onintersecting
ultramafic intrusion estimated to contain about 70% of borehole,h owever,n o prominents catterede ventsf rom
the world'sr eserveso f platinumg roupe lements.I n this the ore zone were evident. Adam et al. reconcile their ob-
case,t he applicationso f seismic-reflectioanr et o identify servationsw ith numericalm odeling,w hich showst hat
different" reef" facies,a ndt o map the extento f a mine- while strongs catteringo ccurs( as expectedfr omt he sig-
planningp roblem referred to as potholes( areasw here nificanti mpedancec ontrasto f the ore depositr elative
the platinum-bearingr eef crosscutsit s own unlithified to the hostr ocks),s eismica mplitudesd ecreasera pidly
footwall and occursu nconformablya t a lowerh orizon). with distancea nd exhibit strongv ariationsw ith offset
Stevenson et al. also describe a new subsurface borehole and azimuth.U sing so-calledd ownholes eismici mag-
techniquec, alledm ine seismicp rofiling,a ndp resentr e- ing (DSI) techniquesP, errone t al. focuso np roblemsa s-
sultsf rom seismics urveysf or base-metael xplorationi n sociatedw ith subsurfacem appingi n structurasl ettings
Namibia. where featureso f interest( e.g., shearz ones,l ithologi-
The nextp aperi n thisp art, by Evanse t al., documents cal contacts)a re subvertical.T he DSI methodc ombines
an experimentasl urfacea nd upholes eismics urveyd e- multioffset,m ultiazimuthV SP dataa cquisitionw ith var-
signedt o delineatea deepd epositn eart he now-depleted ious3 D seismici magingt echniquesT. his approachw as
Mt. Morgan gold mine in QueenslandA, ustralia. The usedt o processa ndi nterpretm ultioffsetV SP dataf rom
data were acquiredi n a challengingn ear-surfacee nvi- a boreholen eart he (abandonedN) orm(cid:127)tal Zn-Cu mine
ronmentc ontainingm ine tailings and abandonedm ine in northwesternQ uebec.T he resultso f this studye n-
infrastructureS. peciala cquisitiona nd processingte ch- abled mappingo f the volcanicu nits of the mine up to
niques, such as the use of extreme statics and VSP- 500 rn away from the borehole,a s well as imagingo f a
derivedv elocities,y ieldeda seismici maget hat suggests tabularg abbroici ntrusiont hat cutsa crosst he dominant
that the depositm ay be more extensiveth anp reviously geologics triked irection.
thought.C learly, old mine workingsr epresenta hostile MultiazimuthV SP surveysh aveb eena parto f Finnish
settingf or surfaces eismics urveys.C alvert et al. com- site surveyi nvestigationsfo r safe disposalo f radioac-
pare 2D seismicp rofiles acrossA nsil and Matagami, tive wastes incet he mid 1980s. Cosmae t al. providea
two of the most importantm ining campsi n the Abitibi comprehensivere view of the techniquesu sed in these
greenstoneb elt of northern Quebec. The many avail- surveys,w ith the objectiveso f detectingh ydraulically
ableb oreholesin theser egionsp rovidee xcellents ubsur- transmissivzeo nes( normallyf racturez onesa nd faults)
face controlf or the interpretationo f seismicr eflections. and determiningt heir geometry.T he core of the pro-
Calvert et al. showt hat it is sometimesp ossiblet o map cessings chemef or these data is the so-calledi mage
synvolcanicfa ultingi n ordert o provided rilling targets. point (IP) transform,a versiono f the radont ransformi n
The interpretationo f these seismicp rofiles is compli- which summationis performeda longh yperbolicp aths
cated,h oweverb, y the pervasivep resenceo f mafic sills. that correspondto the time-depthf unctionso f possible
In addition,o ne seismicl ine recordeda strongr eflection reflectorsT. his approachfa cilitatest he applicationo fco-
from the top surfaceo f a volcanogenicm assives ulfide herencyf ilterst o enhancew eak reflectionsa, nde fficient
orebody,b ut the charactero f the reflectioni s similar to separationo f interferingr eflectionsT. he processinga nd
othere ventsr eflectedf rom nearbym afic sills. interpretationm ethodsa re illustrated using examples
In PartV , boreholes eismics tudiesa rep resentedC. er- from two sitesi n Finland, showinga good correlation
tain hardrocke nvironmentasr ep articularlyp ronet o dis- betweenp rominents eismicr eflectorsa nd hydrogeolog-
tortionso f the seismicw avefieldc ausedb y near-surface ically significantz ones.
layers.T his is oftent he casew herea highly attenuating, Part VI of this volume contains case histories
low-velocityl ayer of variablet hicknesss, ucha s glacial of 3D seismic surveys for deep mineral exploration
till, overliesh igh-velocityb edrock.O ne way aroundt his (Canada) and mine development( South Africa). The
difficulty is to use boreholesi n ordert o place sources, 3D seismic technique involves data acquisition on
receivers,o r both, beneatht he near-surfacel ayer and an areal grid, followed by specializedp rocessinga nd
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