Mine Seismology: Seismic Warning Concept: Case Study from Vaal Reefs Gold Mine, South Africa

212 Pages·2018·6.44 MB·English

by  S.N. Glazer (auth.)

S.N. Glazer
Mine Seismology:
Seismic Warning
Concept
Case Study from Vaal Reefs Gold Mine,
South Africa
Mine Seismology: Seismic Warning Concept
S.N. Glazer
Mine Seismology: Seismic
Warning Concept
Case Study from Vaal Reefs Gold Mine,
South Africa
123
S.N. Glazer
Retired Mine Seismology Consultant
Phalaborwa
SouthAfrica
ISBN978-3-319-62352-8 ISBN978-3-319-62353-5 (eBook)
https://doi.org/10.1007/978-3-319-62353-5
LibraryofCongressControlNumber:2017952934
©SpringerInternationalPublishingAG2018
Thisworkissubjecttocopyright.AllrightsarereservedbythePublisher,whetherthewholeorpart
of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations,
recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission
orinformationstorageandretrieval,electronicadaptation,computersoftware,orbysimilarordissimilar
methodologynowknownorhereafterdeveloped.
The use of general descriptive names, registered names, trademarks, service marks, etc. in this
publicationdoesnotimply,evenintheabsenceofaspecificstatement,thatsuchnamesareexemptfrom
therelevantprotectivelawsandregulationsandthereforefreeforgeneraluse.
The publisher, the authors and the editors are safe to assume that the advice and information in this
book are believed to be true and accurate at the date of publication. Neither the publisher nor the
authorsortheeditorsgiveawarranty,expressorimplied,withrespecttothematerialcontainedhereinor
for any errors or omissions that may have been made. The publisher remains neutral with regard to
jurisdictionalclaimsinpublishedmapsandinstitutionalaffiliations.
Disclaimer:Thefactsandopinionsexpressedinthisworkarethoseoftheauthor(s)andnotnecessarily
thoseofthepublisher.
Coverillustration:©bucky_za/GettyImages/iStockimage187345958
Printedonacid-freepaper
ThisSpringerimprintispublishedbySpringerNature
TheregisteredcompanyisSpringerInternationalPublishingAG
Theregisteredcompanyaddressis:Gewerbestrasse11,6330Cham,Switzerland
A wise man will receive warning, but a fool
will sooner be smitten in the face.
—Coverdale, Proverbs 10:8
I dedicate this book to all those who
contributed towards mine seismology when it
was based on analogue technology. At that
time, being a seismologist analysing and
interpreting data recorded by mine networks
required not only sound knowledge but also
exceptional commitment. It is not surprising
that their research results are still validtoday
and are not replaceable by the today’s
research. My special appreciation goes to
those that were associated with the
Klerksdorp Mine Managers Association’s
Regional Seismic Network.
Preface
The events described in this book took place between the years 1990 and 2000 at
theSouthAfricangoldmineVaalReefs.Myfirstbook(Glazer2016)describesmy
experience as a mine seismologist at Palabora Mining Company (PMC), a South
African copper mine, from 2002 until 2013. These two periods of my life enabled
metomakecertainstatementsontheconditionofmineseismologyinSouthAfrica
as it stands at the end of 2016. Probably less controversial, my first conclusion is
that there is a place for seismology in the mines. The problem is that most mining
personnel are not convinced that there are any benefits from the use of seismic
monitoring. The nonbelievers exist both among the mine managers and the tech-
nical staff. The former are sceptical because they must balance the costs and ben-
efits, which is understandable because this is their job. On technical matters, they
depend on technical staff. The latter, on the other hand, can be divided into those
that know nothing and those that think that they know everything about mine
seismology. In my over twenty years of being a mine seismologist, I have come
acrossonlytwominingengineerswhounderstoodmineseismology.WhatIfound
strange was that very often the technical personnel were more concerned about
saving money for the mine in the short term rather than investing in mine seis-
mology for any future benefits. The reason for this situation is at least twofold.
Installationoftheseismicnetworkinthemineonitsowndoesn’tintroduceany
immediate benefits. These come with time, but only when the seismic network is
managed by a professional mine seismologist. That is the second part of the
problem: there are no professional mine seismologists available to work at the
mines.Theminemanagerassuchisnotinterestedinexaminingrecordedseismicity
inthebackanalysismode.Itdoesn’tmatterifthesebackanalysisexamplesareofa
highstandardorarepurefiction.Theyareaboutthepastandofnohelptothemine.
Whatcountsatthemineisproductionandwhatcanmakeincreaseitand/ormakeit
safer.Thatiswhyrecordedseismicdatahastocontributetowardstoday’sneedsin
themine.And thiscanbedoneonly when theprofessionalmineseismologistisat
the place where the action is, which is at the mine. If he is a professional seis-
mologist, then he will be able to prove to the mine management that seismic
monitoringbenefitsthemine.I know this from my experience. The sad part ofthe
ix
x Preface
story is that it was often easier to convince a mine manager than a rock engineer.
My best practical applications of mine seismology came when I was not related to
the Rock Engineering Section. At Vaal Reefs I was working directly for the
KlerksdorpMineManagersAssociation,andatPMCtheseismicnetworkwaspart
oftheCaveManagementSection.Forsure,theremusthavebeenareasonforthis.
Ibelievethatmostoftherock-engineeringpersonnelemployedbythemines(at
least in South Africa) have no proper knowledge of mine seismology. Knowledge
of any technical subject must be based on sound science. If not, then it is fiction,
anditdoesn’tmatterifthisfictionismixedwithsomescience.Itisstillfiction.This
fiction, when introduced into industry, awakens false expectations that cannot be
achieved. This then degrades mine seismology as a science. As a result, mine
management doesn’t see any use for it. It will still purchase seismic systems and
then appoint amateurs to operate them. In this way, they have done what a rea-
sonable manager would do by installing the system. They are then doing what a
goodmanagerwoulddobyreducingtheworkingcosts.Asaresult,thereareplenty
of operational seismic systems at the mines but there are no practical results. Lack
of those convinces the industry that mine seismology is of no use.
At the present time, mine seismology is in serious regression. This applies to
theory and practice. The good news is the recording hardware for digital seismic
systems.Itisgoodand,whatisevenmoreimportant:ithasbeentestedinpractice.
We know that the seismic-system hardware operates in difficult conditions, and
there is no problem with this part of mine seismology. The setback starts with the
use of the recorded data. With the introduction of digital seismic recording, it was
assumed that all or most of the existing theory is wrong and that it has to be
rewrittenfromthebeginning.Fromthestart,thiswasnotaconcepttotestbutwas
treated as an axiom. The mining industry was bombarded with new ideas and
concepts.Itbecameunclearwhatisaconceptthatstillrequirestestingandwhatisa
pure concept. New theory was presented as being very complex and wrapped in
terminology that was difficult to understand. In this way, mine seismology that,
during the analogue age, had sound theory that resulted in numerous practical
applications became a “black box”. Under such conditions, mine after mine out-
sourcedmanagementofitsseismicsystems.Thesituationsbecameridiculous.The
contractor assumed the role of deciding what the mine requirements from seismic
monitoring might be. In this way, mine seismology and the mine industry went in
two different directions.
I hope that this book will be read not only by those that are interested in mine
seismology but also by the present and future technical mine managers. This book
is full of examples where properly used seismic data enabled solving production
problems and increasing the underground safety standards. I want to believe that,
when given the opportunity, mine seismology will return to the mines.
Phalaborwa, South Africa S.N. Glazer
Preface xi
Reference
GlazerSN(2016)Mineseismology:dataanalysisandinterpretation.Palaboraminecavingprocess
as revealed by induced seismicity, Springer International Publishing, Switzerland, ISBN
978-3-319-32611-5
Contents
1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
2 Seismicity of the Klerksdorp Goldfields and the Resulting
Seismic Hazard. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
2.1 History of Gold Mining in the Klerksdorp Area . . . . . . . . . . . . . 21
2.2 Seismicity of South Africa . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
2.3 The Klerksdorp Regional Seismic Network . . . . . . . . . . . . . . . . 26
2.4 Severity of the Klerksdorp Goldfields Seismic Hazard . . . . . . . . 29
2.5 Upgrade of the Klerksdorp Regional Seismic Network . . . . . . . . 39
2.6 Use of Seismic Data in the Calculation of Support
Resistance for Rock-Burst Conditions at Vaal Reefs. . . . . . . . . . 44
2.7 Summary and Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
3 Concept of Apparent Stress Index . . . . . . . . . . . . . . . . . . . . . . . . . . 55
3.1 Apparent Stress Index and the Energy Index . . . . . . . . . . . . . . . 59
3.2 Development of the Apparent Stress Index Concept
1991–1992. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
3.2.1 Contour Maps of Apparent Stress Index . . . . . . . . . . . . 62
3.2.2 Contour Maps of Apparent Stress Values . . . . . . . . . . . 65
3.3 Examples of Applications of the Stress Index Concept
(1991–1993). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
3.3.1 Back Analysis of a Large Seismic Event
that Occurred on 1 December 1991 at No. 5 Shaft
Vaal Reefs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
3.3.2 Interpretation of Seismic Data Recorded
in the Vicinity of the Clemcor Dyke
from September 1990 to September 1991 . . . . . . . . . . . 72
3.3.3 Back Analysis of a Large Seismic Event
that Occurred on 19 June 1992 at No. 9 Shaft
Vaal Reefs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
xiii