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,Alaska Power Authority
Susitna Hydroelectric Project
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Subtask 4.09
DESIGN MANUAL FOR
THE LONG-TERM EARTHQUAKE MONITORING SYSTEM
FOR THESUSITNA HYDROELECTRIC PROJECT
June·1982
Prepared by
~Woodward-Clyde Consultants ..,
for
Acres American Incorporated
ARLIS
Alaska Resources
Library &Information Servtces
AnCl~Q!'qge.Alaska
1000 Liberty Bank Building
Main at Court
Buffalo,New York 14202
Telephone:(716)853-7525
Woodward-Clyde Consultants
TABLE OF CONTENTS
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1 INTRODUCTION
2 DATA REQUIREMENTS
2.1 Hypocentral Locations
2.2 Focal Mechanisms
2.3 Magnitudes
2.4 Source Parameters and Attenuation
2.5 Strong-Motion Data
3 NETWORK CONFIGURATION AND SITE SELECTION
3.1 High-Gain Station Configuration
3.2 Strong-Motion Station Configuration
4 INSTRUMENTATION
4.1 Instrumentation System Design
4.2 preliminary Instrumentation Specifications
and Estimated Costs
4.3 Strong-Motion Instrumentation
4.4 Implementation and Schedule
5 OPERATIONAL RESPONSIBILITIES
REFERENCES
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1 INTRODUCTION
Woodwa rd-Clyd e COnsul tants (WCC)conducted de tailed seismic
hazard studies as part of the feasibility assessment of the
Susitna Hydroelectric Project (WCC,1982).For this project,
possible earthquake sources and associated strong ground-motion
potential that could affect the Project si tes were evaluated.
The results of these studies suggest that relatively strong
ground motions could occur at the Project sites during the
lifetime of the facilities.To further evaluate the effect that
these motions will have on the seismic design and performance of
the dam and auxiliary structures,it is important to collect data
during earthquakes that may occur prior to,during,and
subsequent to design and construction,of the dams.Collection of
these data requires the installation of suitable instrumentation
prior to the occurrence of such motions.
Th e purpose of this report is to discuss the instrumentation
design and operational features of a long-term earthquake
rnoni toring system for the Su si tna Project.Th is discussion
incorporates general considerations on seismic instrumentation
for dams (Bolt and Hudson,1975;Sharma and Raphael,1981)as
applied to the specific seismic and operational environment of
the Susi tna Project (Woodward-Clyd e Consul tants,1981 and
1982)•
Se ismic instrumentation for the Su si tna Project has two major
objectives:1)to provide important data for the continous
monitoring of the earthquake environment of the project,
particularly with respect to the possible occurrence of
reservoir-induced seismicity;and 2)to provide necessary data
for evaluating the engineering severity of strong ground motions
that may occur at the site.The instrumentation and the data it
provides are thus important in evaluating the seismic design of
the project and in monitoring the performance of the design under
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seismic loading.To satisfy these objectives,two subsystems of
instrumentation should be operated.
•First,a network of sensitive (high-gain)seismograph
stations should be operated to allow for the detection and
location of earthquakes of magnitude approximately 1 and
larger.The area of coverage of these stations should be
within 30 km of the reservoir system axis,since this is
the area considered potentially susceptible to reservoir-
induced seismicity (Woodward-Clyde Consultants,1982).
This network should be installed several years prior to the
construction of the reservoir in order to establish a
stable baseline of earthquake data against which to compare
possible post-reservoir-filling changes in the seismic
environment.Operation of the network should continue for
a t least 10 years after filling,as this is the time
interval during which indu'ced seismicity is more 1 ikely to
occur.
•Second,strong-motion (low-gain)instruments should be
opera ted to record the effects at the dam sites of any
strong ground shaking (accelerations exceeding 0.01 g).
These instruments should be placed on the abutments and
their near vicini ty in locations that will not cause the
recorded ground motions to be modified by local geologic
condi tions.Th e high-g ain data accurately identi fy
hypocentral locations of earthquakes generating strong
ground motions.
Four key system characteristics should also be emphasized in
_developing the instrumentation system.
•The system should yield data of uniformly high quality and
optimum utility.
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•The instrumentation should be highly reliable.To ensure
th is reI iab il i ty,the instrumentation should provide
redundancy of functions,it should be environmentally
hardened,and it should be proven in the field.
•Sophisticated instrumentation consistent with proven
reliable operation should be used to reduce long-term
operational costs and maintenance costs.
•Automated functioning should be used to rapidly provide the
system operators with data upon which good engineering and
public safety decisions can be made.
Recommendations for the design of the long-term earthquake
monitoring system for the Susitna project are developed and
presented in this report on the basis of the above system
objectives and key characteristics.The data requirements and
field station configuration,as they influence design,are
discussed in ~ctions 2 and 3.Recommendations for the
instrumentation design are presented in Section 4;Section 4 also
identifies representative components and their costs as of
January 1982.~erational responsibilities for the system are
discussed in Section 5.
It is expected that this report will be used for planning
purposes in proceeding wi th the design of the Susi tna
Hyd roelectric Project.Appropr iate review and finalization of
the instrumentation design should be carried out in conjunction
with the next stage of overall Project design.Procurement
documents can be based on the design and cost elements of Section
4.The resulting operational system should well serve the
Susitna Project and the Alaska Power Authority.
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2 ~TA REQUIREMENTS
The design of the Susitna Project long-term earthquake monitoring
system is derived from the kinds of data from recorded earth-
quakes that are required for engineering and operational
purposes.These data include hypocentral locations,focal
mechanisms,magnitudes and other source parameters,and strong
ground motions.The following discussion explains the data
requirements and specifies the measurements to be made for each
recorded earthquake.
2.1 Hypocentral Locations
Earthquake hypocentral locations form the basis for all detailed
investigations of seismicity.The area of interest for the
Su si tna Hyd roelectric Project is centered around the darns and
lies within 30 km of the reservoirs;it is also expected that
this area could be influenced by the earthquake-inducing effects
of reservoir filling.Spatial and temporal patterns of
naturally-occurring local seismicity will form a baseline against
which the possible seismic effects of reservoir filling can be
identified and evaluated.Considering the relatively low level
at which these possible changes in seismicity patterns may be
initially observable,hypocenters within the crust should be
accurate to within a kilometer.Hypocenters in the Benioff zone
below the crust should be accurate to within approximately 5 km.
Several factors control the accuracy with which hypocenters can
be determined.'Ihese include:1)station spacing and azimuthal
coverage;2)the accuracy with which arrival times can be
determined;and 3)how well the velocity model used represents
the veloci ty structure of the crust under the network.For
locating crustal earthquakes,a station spacing of 10 to 15 km is
usually adequate.Focal depths less than about 5 kIn may be
inaccurately determined if the closest station to the event lies
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more than 5 krn from the hypocenter.Such extremely shallow
even ts are not expec ted to be common in the area;however,if
they do occur,accurate depths may be calculated by using
waveform modelling or other advanced techniques.For the second
factor,proper identification of P and S waves is needed so that
correct travel paths can be specified in the computer program
used for determining hypocenter locations.The use of three-
component seismometers at several stations should provide
unequivocal phase identifications.FOr the third factor,a local
velocity model should be developed and refined by crustal
refraction and time-term stud ies.It is anticipated that
sufficient data for these studies would be provided by network
recordings of local blasts associated with construction of either
or both of the darns (and perhaps by a 1 imi ted number of blasts
detonated specifically for crustal structure investigations).
Measurements needed to provide hypocentral locations are the
arrival times of correctly identified P-wave and S-wave phases at
the network stations.Absolute timing is needed to wi thin 0.01
seconds.
Focal Me chanisrns
Well-constrained,accurate focal mechanisms are important to
further evaluate the correlation of seismicity with geologic
s true tures and to assess the orienta tion of tectonic stress in
the area.Factors affecting the accuracy of focal mechani sms
includ e:the accuracy of hypocentral locations,particularly of
focal depth;the location of the earthquakes relative to the
network;and the accuracy of the local velocity model.
Measurements needed to obtain focal mechanisms are the direction
of motion of p-waves and S-waves and undistorted waveforms of the
)p-and S-waves.
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2.3 Magnitudes
Ac curate magni too es are important in characterizing the local
seismicity patterns before,during,and after filling the
r eservoi rs.In order to produce a homogeneous data set,the
local magnitude scale should be consistent for all areas of the
network.IDcal magnitude values must be calibrated against the
standard Richter magnitude scale (M L ),thus producing equivalent
~ML values for the study area.
Measurements needed to calculate magnitudes are the durations of
seismic wave codas recorded at low-noise stations and the un-
distorted maximum amplitudes of ground motion at all amplitude
levels.
Earthquake source parameters that can be estimated from waveform
modelling and spectral analysis of local network data include
stress drop,fault displacement,rupture dimensions,and seismic
moment.These parameters are extremely useful in investigating
the details of earthquake source processes and in assessing the
magnitude and orientation of local tectonic stress.Compilation
of these parameters over time will aid in identifying possible
changes in the local seismic environment.Determination of the
seismic attenuation characteristics of the local crust provides a
basis for the calculation of ground motions at the site resulting
from local earthquakes.These characteristics will be very
useful in analyzing data from strong-motion accelerographs at the
sites in order to evaluate site-specific ground motions.
Knowledge of seismic attenuation characteristics is also
necessary for the successful determination of earthquake source
parameters.Seismic attenuation studies will involve similar
waveform and spectral analysis of local network data as for
source parameter studies.
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2.4 Source Parameters and Attenuation
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The primary requirement for waveform and spectral analysis is
dig i tally recorded data from an accurately calibrated network.
At least one three-component station with a broad frequency
response in the range 10 seconds to 50 Hz is desirable.An
additional three-component station would enhance the scope and
reI iabili ty of source parameter and attenuation studies.The
network has been designed on the basis of state-of-the-art
techniques in computational seismology:it is anticipated tha t
advances in this field wi thin the next five years will further
increase the usefulness of such studies.
The measurements needed to calculate source
undistorted whole seismograms recorded by
stations.
2.5 Strong-Motion Data
pa rame ters are
well-calibrated
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The recording of possible strong ground motions at the foundation
(free-field)level of the Watana and Devil Canyon si tes is of
high value in evaluating the performance of the seismic design of
the dam.
Ground motions from moderate (M S 5)and larger earthquakes within
about 100 km of the dam sites should trigger the strong-motion
recorders as well as be recorded by the high-gain seismograph
stations.The acceleration data will be recorded on self-
contained,independent accelerographs wi th a trigger level of
about 0.01 g and a peak dynamic range of at least 1.0 g.
Measurements needed to evaluate strong ground motions at the site
are undistorted three-component records of the ground motions of
an earthquake following the first time in the motion that 0.01 g
(the trigger level)is exceeded.The data must be in the
frequency range from 0 to 20 Hz and must be of good enough
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quality to put in digital form.Absolute time should be recorded
r-for correlation with the high-gain data.
3 NETWORK CONFIGURATION AND SITE SELECTON
The planned configuration of the stations of the long-term
earthquake recording system is discussed in terms of the high-
gain network and the strong-motion stations.'!he generalized
configuration of the stations is shown in Figure 1.
3.1 High-gain Station Gonfiguration
As currently planned,the central recording facility for the
high-gain network will be located at the Watana dam site,which
is the geographical center of the system.If the camp is
maintained during the construction phase,as we assume it will
be,a reliable 110 VAC power .supply,necessary to power the
recording system,will be available at the Watana camp.The
Watana camp is also a convenient location for the routine
operation of the network,as described in Sections 4.1 and 5.
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The high-gain network for the Devil canyon-Watana reservoir
system consists of 13 field stations;the data from these
stations will be telemetered by VHF radio or hard wire to
Watana.The preliminary locations of the stations,as shown in
Figure 1,provide reasonably uniform coverage of the area within
approximately 30 km of the reservoirs.The best azimuthal
coverage (greater than 180 0 from the hypocenter to the stations)
is provided for the region lying within about 15 km of the
reservoirs.Final selection of field station sites will be based
on the results of a seismic noise survey,using a portable
instrument in the field to identify the quietest sites at the
localities shown.The distance between closest station pairs is
approximately 15 to 20 krn,and the majority of earthquakes that
occur within 20 kIn of the reservoirs will be at an epicentral
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cl istance of less than 10 kIn from one of the stations.Th e
,'-'network,therefore,is des igned to provide good constraint (±1
to 2 km)on the hypocentral locations of earthquakes that occur
within 30 km of the reservoirs and with focal depths greater than
approxima tely 5 kIn.Fa ir control (±3 kIn)on focal depths
shallower than 5 kIn will be ach ieved,but this control will
decrease for very shallow earthquakes unless they happen to occur
very close to an individual station.
Eleven of the stations are planned to have vertical-component,
one-second free period seismometers.The remaining two.will be
three-component stations.'Ih e first of these two,located near
the Watana site,is planned as a three-component,broad-band
system,wh ich is located close to the rock-site strong-motion
accelerograph (see Section 3.2).Data from this station will be
transmitted by hard-wire to the recording facility.This station
will provide high-quality,broad-band data for spectral analysis
and for ground-motion evaluations.The location of the second
three-component station is planned near the western end of the
array.Th is station wi 11 incorporate one-second free period
seismometers and will provide additional data for shear wave
identification and for spectral analysis.Since data from this
s'tation will be multiplexed and telemetered by VHF rad io 1 ink,
the instrumentation could be relocated to any other station site
to optimi ze the collection of three-component data.Two of the
v1ertical-component stations and both of the three-component
stations will be dual-gain.This will allow for a wider dynamic
range (about 100 db above noise)and should allow for on-scale
recordings over the range of microearthquake motions to strong
motions recorded on the accelerographs.
The configuration of the high-gain stations,as shown in Figure
Iv covers both reservoirs.If the Devil Canyon construction is
to follow the Watana dam by more than a year or two,installation
of the four westernmost stations could be delayed wi thout compro-
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mising the data obtained for the Watana dam.In that case,the
~-t.hree-component station could be moved to the station si te due
east of Watana camp.
3.2 Strong-Motion Station Cbnfiguration
During the pre-construction phase,strong-motion instruments
should be installed at three locations for each dam site:one on
each of the two abutments in a posit.ion that is out of the way of
immediate construction activi ties,and one at a bedrock si te
within a few kilometers of the abutments.The final locations of
the two abutment instruments must be determined on the basis of
detailed construction plans.The bedrock site should be planned
in conj unction with the three-component broad-band instrument.
A.ccess to the accelerometers is required for maintenance and
calibration on a regular schedule and after the occurrence of an
earthquake that generates strong ground motion.
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Following construction of the dam,
recorders should be installed wi thin
crest of the dam.Placement of these
the final configuration of the dam.
4 INSTRUMENTATION
additional strong-motion
the galleries and on the
instruments will depend on
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The design of the instrumentation system needed to carry out
successful long-term seismic monitoring at Susi tna is described
here in generic terms.section 4.1 presents the design factors
used to select the instrumentation system that meets the data
requi rements of Se ction 2.se ction 4.2 a nd Table 1 describe the
components for the field stations and central recording facility,
give examples of representative available equipnent,and present
a cost estimate for the instrumentation.Section 4.3 discusses
the strong-motion instrumentation.
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4.1 Instrumentation System Design
The system design is based upon the use of a triggered,
microcomputer-based recording system to record data at the
central recording facility located at the Watana site.Data will
be telemetered from the remote field stations to Watana as
modulated VHF radio transmissions.Data from the three-
component,broad-band station near Watana will be transmitted
using a hard-wire link.At the central recording facility,the
signals will be demodulated and digitized in real time and input
to the microcomputer,where a sophisticated earthquake detection
a.nd discrimination algori thIn will continuously scrutini ze the
incoming signals on all channels.The incoming data will
initially be stored on disc.When a seismic event is detected,
the digitized data will be copied from disc to tape for permanent
storage.Recording will cease when the detection algorithm
declares the event to be over.
Da ta from selected stations wi 11 also be recorded on six drum
recorders that prod uce analog paper records.Earthquake data
will be retained on disc for at least several hours after the
event,together with summaries of the network status,number of
events recorded,and other operational information.These data
will be accessible via a dial-up telephone telemetry link for
rapid transm i ttal from Wa tana to distant locations.Da ta from
t,ape or disc will also be available for preliminary data analysis
using the microcomputer.Such analysis can be carried out
without interrupting the primary data acquisition function of the
computer.Absolute timing will be provided by a self-correcting
crystal-controlled clock,which will be continuously synchronized
to satellite standard time broadcasts;back-up timing will be
provided by a second crystal-controlled clock and a wwv time code
receiver.
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The microcomputer-based system will provide the flexibility,data
quali ty,and low operational and maintenance manpower which are
i.deally required for the long-term monitoring program.Important
factors in the design of the system are discussed below.
(a)Capability to Acquire Desired Data:The data needs
discussed in Section 2 indicate that the following features are
necessary:
-timing accuracy of 0.01 seconds,referred to Universal
Coordinated Time,to achieve location accuracy.
-centralized recording to simplify the routine operation of
the network and data analysis.
triggered digital recording of earthquakes to minimize the
vol ume of dig i tal data saved.
-mul tiple-gain recording for selected stations to provide a
wide dynamic range.
-well-calibrated digital data to allow for high-quality
source and attenuation analyses.
-preliminary local data processing to allow dam operators to
respond appropriately to potentially significant
earthquakes.
All of these features can be provided by a computer-based system
as described above.In particular,it will be possible to use a
more effective triggering algori thIn wi th a computer-based system
than with alternative systems,such as existing digital event
recorders.Th is is because the capaci ty of the computer allows
the algorithm to be sophisticated,while at the same time the
algorithm can be finely tuned to the prevailing field site
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condi tions by reprogramming at the central recording facill ty in
a high-level computer language (such as FORTRAN)by an operator
~d th only moderate programming expertise.Analog recording
systems,such as FM tape or Develocorders,will record
continuously,and hence a large amount of background recording
\<trill either have to be edited or archived.The capability to
carry out relatively sophisticated preliminary data analysis at
the recording site will be provided by the microcomputer.This
could be carried out automatically (on-l ine)or interactively
without the need to produce and analyze analog paper records from
cassettes or FM tape.
(b)Re liabili ty and Ma intenance:In order to maximize the
amount,continuity,and quality of data recorded and to minimize
costs for major maintenance,the instrumentation chosen for the
system must be capable of operating reliably for long periods of
time (up to two years)without significant maintenance or
adjustment.This is particularly true for the field I station
instrumentation,which must be capable of withstanding the severe
environmental cond i tions of the Susi tna area.Many of the field
stations will be inaccessible for several months each year,and
failures at these stations will involve the loss of data for long
periods of time.Instrument reliabili ty can be maximized by
first choos ing instruments with proven performance.The
reliability of the system as a whole can be further enhanced by
careful installation and by environmentally hardening the field
sites to wi thstand antic ipa ted condi tions.Experience in field
operations in Alaska gained by Woodward-Clyde Consultants,the
University of Alaska Geophysical Institute (UAGI),and the U.S.
Geological Survey (USGS)has been incorporated into the
recommended system design.
(c)a=dundancy:The system must incorporate sufficient redun-
dancy to accommodate component failures without significant
impairment of operations or data quality.Redundancy in data
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acquisition is incorporated by operating a sufficiently large
~.network so that temporary loss of several stations due to severe
weather conditions or lack of maintenance access at remote sites
is not likely to significantly degrade data quality.Sufficient
repl acement parts should also be maintained at the central si te
t.o allow some repairs to be made without substantial technical
support from outside the network area.
R.edundancy in recording will also be incorporated by providing
multiple means of data recording.Primary recordings will be
made by a computerized earthquake detection and recording
system.Detected events will be preliminarily located,then
dubbed onto a digital tape for further analysis later.Backup
will be provided by three dual-channel pen recorders that will
monitor six of the 13 stations on paper records.The earthquake
data will also be available to off-site agencies via dial-up
telephone data transfer.
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(d)Rapid Data Access:The instrumentation design will allow
for immediate (within a few minutes)availability of preliminary
earthquake locations as we 11 as access to arrival time data.
Thus,should an earthquake generate significant ground motions,
the location will be available for revision and possible action
by APA or other agencies on the basis of accurate seismological
i nforma tion.
(e)Routine Operation and Maintenance:Routine operation and
maintenance at the Watana site will consist of record changing at
the central recording facil i ty,monitoring the performance of
the system on a regular basis,minor maintenance such as changing
batteries and adjusting telemetry levels,documenting the network
operation on a day-to-day basis,and performing prel iminary data
analysis.Re cord-changing activi ties will be minimized by using
the triggered computer-based system.In addition,other
activities,such as performing time corrections and calibrations,
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will be automated.'!he computer-based system will maintain a
continuous diagnostic check on its own operation and on the
condition of incoming signals,and will generate diagnostic
messages.Data reduction and analysis will also be automated,as
described in Ca)above~this will greatly streamline these
operations and reduce operational manpower costs.
4.2 Preliminary Instrumentation Specifications and Estimated
Costs
A list of the instrumentation planned for each type of field
station and for the central recording facility is shown in Table
1.Basic specifications for the components are also given.'!he
slecond col umn of Table 1 gives examples of commercially available
components that would be suitable for the system.Table 1 is not
a procurement document,and these specific models are included
only to illustrate the types of components that are available and
to enable the cost of the system to be estimated~alternative
instrumentation that would be equally suitable is available from
other manufacturers in many cases.Cost estimates are based on
manuf acturers'quoted prices as of Ja nuary 1982.When the
n4~twork is implemented,Table 1 will serve as the basis for
preparing a procurement document.
Environmental hardening of the field stations will consist
primarily of mounting the radio antennas and electronics packages
on 20-foot-high towers.'!his will reduce the chance that the
antennas may be buried under snow or that they may be harmed by
animals.'!he towers are sUbstantial,rigid structures set in
concrete bases to enable them to withstand snow and ice loading
and high winds.'!he battery enclosures are SO-gallon drums with
foam insulation set in concrete.Together with modifications of
the voltage controlled oscillators to ensure temperature
stability and fabrication of automatic calibration modules,these
fl=atures increase the cost of the entire system by about $50,OOO~
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however,they are judged to be necessary to provide highly
reI iable continuous data recording from the stations and to
minimize maj or maintenance.'!he relay stations included in the
cost estimate may not be needed,depending on the final station
configuration of the network.
The cost estimate for the central recording facility includes the
cost ($150,000)of a complete computerized data acquisition
system.'Ih is system includes the central processor unit,analog
to digital convertor,disc drive and discs,dual tape drives,
terminal,printer,and interfaces.Al ternative modes of data
recording were considered for the project.These alternatives
and their estimated costs are:nine digital event recorders with
an array trigger device and associated playback equipment,
$84,000;two FM tape recorders plus associated playback equipment
(not including digitization facilities),$93,000:and three
Develocorders and associated equipment and a viewer/copier,
$123,000.However,because none of these alternatives allow for
automation of the data processing or for telephone access to the
data,they were not considered further.Also,because the
alternatives require additional personnel time for maintenance
and data reduction,any immediate cost savings would be
eliminated when prorated over the lifetime of the array.
The uninterruptible power supply provides regulated,frequency-
stabilized 110V AC power regardless of fluctuations in line
power,and back-up power for up to four hours in the event of
1 ine powe r failure.
with regular maintenance (see Section 4.4),the average operating
life of individual electronic components of the system is
expected to be in the range of five to eight years.However,it
is estimated that approximately 8 to 10%of the field equipment
if will need to be replaced every year to maintain the system in a
1 fully operational condition.Therefore,over the projected 10-
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year or longer period of monitoring,it is expected that the
equivalent of the entire system will be replaced at least once.
4.3 Strong-Motion Instrumentation
The strong--motion system planned for the preconstruction phase
consist of three independent,internally triggered,battery-
operated strong-motion acceleration recorders for each dam
site.For reliability of long-term operation in a rugged
environment,70 mm film recorders are recommended.Internal
timing should be included to allow for earthquake identification
and comparison with the high-gain data.Suitable instruments are
listed in Table 1.Routine maintenance can be carried out in
conjunction with the operation of the high-gain system.
In the post-construction phase,a more sophisticated strong-
motion system,incorporating free-field and structural
accelerographs with digital recording and rapid operator readout,
should be instal~ed.At that time,the film recorders will serve
as backup recorders .
4.4 Implementation and Schedule
The next steps in implementing the Susitna Project network would
ble to finalize the system design on the basis of the generalized
design presented in Sections 3 and 4 and to prepare bid
documentation for the hardware.Finalization of the design will
take into consideration any experience or developments in
instrumentation available following the date of this report.The
instrumentation will then be procured and the system assembled.
The entire system will be fully tested and calibrated prior to
installation in the field.Meanwhile,the location of the field
sites will be finalized by field reconnaissance,radio line-of-
sigh t transmission tests,and a noise survey using a portable
s!eismograph.If the potential schedule shown in Table 2 is
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followed,the network will begin operating nine months after
authori za tion.
The estimated level of effort required for implementation of the
network is shown in Table 3 in terms of person-days.The
estima ted salary costs shown in Table 2 are based on V\Qodward-
Clyde Consultants'1982 schedule of charges.
T'able 4 presents estimated personnel time requirements and costs
for the routine operation and maintenance of the network and for
data analysis.Item 1 covers visits to the site by outside
technicians for non-routine maintenance,such as equipment
repairs and major recalibration.Most of the other estimated
yearly cost for Items 1 and 2 is for helicopter support,which
has been estimated at $500 per hour.
5 OPERATIONAL RESPONSIBILITIES
The successful operation of the long-term earthquake moni toring
system is based on support and di rection provided by the Alaska
Power Authority.While the specifics of the operational
assignments may shift in order to respond to changes in agency
capabil i ties or other factors,a focused program direction mus t
be maintained by APA so that the data are of high quality and are
appropriately available to APA to allow safe and proper operation
of the Susi tna Hyd roelectric Project.Th is level of responsi-
bility is consistent with the APA's primary financial
responsibility for the long-term earthquake monitoring program.
Personnel located at the central recording site (Watana Camp)
will be responsible for field operations,including record
changing,maintenance,and preliminary data analyses.This will
require training of several part-t ime staff who will be in
residence at the central recording site.The results of the
preliminary data analysis and the digi tal tapes and analog
18
Woodward-Clyde Consultants
records will then be sent out for review,final analysis,and
interpretation,as described below.The APA should verify that
iehe seismic record archives are adequate and ,that the system
operation is well documented.
Under the APA's overall direction,the primary technical and
review responsibility for data quality and data interpretation
~dll be held by seismologists wi th the expertise necessary to
meet the objectives of the long-term monitoring program.All
preliminary locations and data analysis carried out by the field
personnel will be reviewed and finalized by these seismolo-
gists.The resulting sLnnmary reports of seismic activity will be
issued by the APA.Data analysis procedures and instrument
calibrations will be reviewed by appropriate seismological
specialists.Depending on the capabilities of the field
personnel,additional personnel may be needed to carry out non-
routine field maintenance and major maintenance as needed.Also
on an as-needed basis,seismological experts will provide review
and assistance ,to the APA in responding to possible safety-
I,"elated issues derived from the monitoring program.
During the ongoing operation of the monitoring network,the APA,
other state agencies,and all parties interested in the safe and
effective operation of the Sus i tna Hydroelectr ic Proj ect will
benefit by the compilation of a reliable,high-quality,and well-
documented data set.Specific procedures and computer programs-~lill change as newer and more effective techniques are made
available.Data storage and retrieval methods will also vary,
~depending on further evaluations of the role and capabilities of
"
the Alaska state agencies.The commitment on the part of the APA
r to conduct long-term monitoring should ensure a successful
monitoring program.
f'I1
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REFERENCES
Bolt,B.A.,and Hudson,D.E.,1975,Seismic instrumentation of
dams:Journal of the Geotechnical Engineering Division,
Proceedings of the American Society of Civil Engineers,v.
101,no.GT 11,Nov.1975,p.1095.
Sharma,R.,and Raphael,J.,1981,seismic considerations,in
General considerations on reservoir instrumentation:Committee
on Measurements of the United States Committee on Large Dams,
Washington,D.C.,13 p.
Woodward-Clyde Consultants,.1980,Interim report on seismic
studies for Susitna Hydroelectric Project:Report prepared
for Acres American Inc.,Buffalo,New York,202 p.and
appendices.
Woodward-Clyde Consultants,1982,Final report on seismic studies
for Susitna Hydroelectric Project:Report prepared for Acres
American Inc.,Buffalo,New York,187 p.and appendices.
20
~'1 -1 ]~'l -1 -'--~.--}1
Table 1:REPRESENTATIVE INSTRUMENTATION AND ESTIMATED INSTRUMENTATION COSTS FOR THE
SUSITNA LONG-TERM SEISMIC MONITORING SYSTEM (1)
(Page1of6)
'"....
ITEM
Field Stations
1)VI:!rtical-component,short-
period,high-gain single,
channel field station
Compri sed 0 f:
I-second free period
seismometer
Fi eld telemetry system,
temperature stabilized,
'With 2-channel relay
capability (incorporates
seismic amplifier,voltage
controlled oscillator,
auto-calibration module,
and multiplexer/band-pass
filters)
REPRESENTATIVE
SUPPLIER/MODEL NUMBER
Mark Products
L4-C-B
Sprengnether,PI'S-8
(auto calibration
module and multi-
plexer/band-pass filters
to be fabricated)
UNIT
COST (1)
$8,150
QUANTITY
9
TOTAL
COST (1)
$73,350
VHF transmitter,250 milliWatt lIt>nitron TX-lOl
Yagi antenna Scala CAS-lSOH
8 carbonaire batteries McGraw-Edison
2 DC-DC convertors Wall Industries
Environmentally sealed
electronics enclosure
Insulated battery
enclosure
Hoffinan Enclosures,Inc.
(to be fabricated)
1 "J ").~"]~l -'1 '-]._}1 1 I "1
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Table 1 (Page 2 of 6)
ITEM
20 ft,self-supporting
antenna tower,to withstand
100 mph wind and 250-lb ice
load
2)Ve rtical-component,short-
period,dual gain channel
field station;
Comprised of:
The same components as in
(1)plus:
1 additional amplifier
1 addi tional veo
Additional field enclosure
3)3-component,dual-gain short-
period field station
Comprised of:
The same components as
in (1)plus:
2 horizontal,I-second
free-period seismometers
4 additional amplifiers
4 additional veo's
REPRESENTATI\'E
SUPPLIER/MODEL NUMBER
Sprengnether AS-110
Sprengnether TC-lO
(to be fabricated)
Mark Products L4-e-H
Sprengnether AS-110
Sprengenther TC-lO
UNIT
COST (1)
$9,575
$12,550
QUANTITY
2
1
TOTAL
COST (1)
$19,150
$12,550
""~""1 "1 1 --~1 1 }""j 1 1 ''-1 ~
i
Table 1 (Page 3 of 6)
l\)
w
ITEM
4)3-component,broad-band
field station,hard-wired to
central recording site
Comprised of:
Vertical seisnometer,
5-second free period
2 horizontal seismometers
5-second free period
6 amplifier/VCO's
2 calibration modules
2 multiplexers
2 field housing units with
voltage regulator in
environmentally sealed
enclosures
2 miles "Spiral-4"cable
5)Relay station
(estimated maximum 2)
Comprised of:
Mul tipl exer/band-pass
filter unit
VHF transmi tter
REPRESENTATIVE
SUPPLIER/MODEL NUMBER
Kinemetrics SV-1
Ki nemetrics SH-l
Kinemetrics AOM-1
Kinemetrics CM-1
Ki nemetrics
Kinemetrics TH-3
(environmentally hardened)
'lb be fabricated
r.t>nitron TX-IOl
UNIT
COST (1)
$14,750
$5,550
QUANTITY
1
2
TOTAL
COST (1)
$14,750
$11,100
o~-eccel 1 i 1 ----1 ~-,J -1 ---1 1 )J 1 -,)'}
Table 1 (Page 4 of 6)
'"~
ITEM
Yagi antenna
6 carbonaire batteries
Environmentally-sealed
electronics enclosure
Insulted battery enclosure
20'lattice tower
ESTIMATED TOTAL FIELD STATIONS COST
Central Recording Facility
Microcomputer-based central
recording system
Comprised of:
Computerized data
aoquisition system
12 Ya~i antennas
12 VHF receivers
18 discriminators
6 discriminators
3 discriminator card cages
3 discriminator power supplies
1 discriminator card cage
1 discriminator power supply
REPRESENTATIVE
SUPPLIER/MODEL NUMBER
Scala CAS-150H
M::Graw-Edison
Hoffman Enclosures Inc.
To be fabricated
W:>oQ./a rd-Clyd e Co nsol tants
Scala CAS-150H
M:>nitron RX-10l
Sprengnether TC-20
I<i nemetrics OM-l
Sprengnether CG-l
sprengnether PS-2
Kinemetrics DP-l
Kinemetrics PP-l
UNIT
COST (1)
$215,000
QUANTITY
1
TOTAL
COST (1)
$133,750
$215,000
---1 -1 ]1 -1 )1 1 1 J i
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VI
Table 1 (Page 5 of 6)
ITEM
Uninterruptib1e power supply,
4 I<Wa tt
2 visual recorders,
2 -channel,wi th
amplifiers
Satellite-corrected clock
WWV receiver
Crystal-controlled clock
2 racks
2,20'lattice towers
REPRESENTATIVE
SUPPLIER/MODEL NUMBER
sprengnether VR-60
True Time 468-DC
True Time WVTR
sprengnether TS250
Sprengnether RRC-6
UNIT
COST (1)QUANTITY
TOTAL
COST (1)
ESTIMATED TOTAL CENTRAL RECORDING FACILITY COST
Strong-Motion Recorders
$215,000
Stron~otion acce1erograph,
wi th integral WWVB t:ime-
c ode receiver Kinemetrics SMA-1 $3,250 6 $19,500
ESTIMATED TOTAL STRONG~OTION RECORDER COST
Te st Equipnent
Comprised of:
$19,500
$6,000
Dual-channel oscilloscope,Tektronics RS110,with
5A18N and 5B10N plug-in
f\)
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Table 1 (Page 6 of 6)
ITEM
Field oscilloscope
Fr equency counter
Function generator
Digital mu1timeter
ESTlMATED TOTAL TEST ~unMENT COST
ESTIMATED TOTAL EQUIPMENT COST(2)
1
REPRESENTATIVE
SUPPLIER/MODEL NUMBER
Tektronics 212-02
Hew1 ett-Packard
5315A +120 +001 +002
Exact Electronics
NIDL.119P (battery
powered)
Hew1et t-Packar d
3466!\.(battery
powered)
-)
UNIT
COST (1)QUANTITY
1
TOTAL
COST (1)
$6,000
$374,250
Notes:(1)The representative instrumentation and costs presented in this table are intended to specify the
design features of the long-term earthquake monitoring system for the SUsitna Hydroelectric
Project and do not constitute a procurement document.These cost estimates are based on 1982
dollars.
(2)Spare parts are shown in Table 4.
,""",
TABLE 2:ANTICIPATED SCHEDULE FOR IMPLEMENTATION OF LONG-TERM NEWORK
-
ACTION
Finalize design and prepare
bid documents
Order equipnent
Receive and test equipment
installation materials
Select station sites
Install and test system
Initiate routine operation
MONTH AFTER START (1)
1
2
6
7
8
9
Note:(1)Field conditions require that installation occur during the
sunmer (months 7,8,and 9).
27
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TABLE 3:ESTlMATED PERSONNEL TIME COSTS AND EXPENSES THROUGH SYSTEM INSTALLATION
Task
Estimated
Pe rson-Days
Estimated
Salary (bsts(1 )
other
Es timated costs(1 )
Estimated
Total COst
1.Finalize systen design 15 10,000 -10,000
2.Prepare procurement 10 6,000 2,000(2)8,000
document and receive
equipment
3.Carry out systen integra-
tion,bench-41sting,and
calibration(15 14,000 -14,000
4.Select sites,install
""system,and check
to operations.125 63,000 50,000(3)113,000
Total 165 $145,000
Notes:(1)Based on estimated 1982 costs,including office expenses.
(2)Shipping costs.
(3)Shipping,per diem,travel,and helicopter costs.
(4)Estimated costs for instrument modifications
and fabrication are included in Table 1.
1 J 1 1 I 1 1 1 1 1 J )
TABLE 4:ESTIMATED YEARLY PERSONNEL TIME COSTS AND OPERATING EXPENSES FOR
NETWORK OPERATION,MAINTENANCE,AND DATA ANALYSIS
Item
Estimated
Person-days
Per Year
Estimated
Yearly Salary
Cost (1)
other Estimated
Yeart1
Costs )
Estimated
Total Cost
1.Maintenance visits by 25 12,500 13,000 (2)25,500
technician to field
stations and central
recording facility
2.Network routine 180 25,000 10,000(3)35,000
operation,preliminary
data analysis
(site Per Sonne I)
lIJ
\0 2,000 (4)3.Detailed data 180 30,000 32,000
analysis and operations
review
4.Replacement Parts ----$36,000(5 )36,000
ESTIMATED TOTAL YEARLY COST $128,500
Notes:(1)Based on estimated 1982 costs.
(2)Travel,per diem,and helicopter costs.
(3)Travel,per diem,helicopter,recording
supplies,and data shipping costs.
(4)Travel and per diem costs.
(5)Based on 10%of the original equipment cost.
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LEGEND
A Vertical-component,short-period,teiemetered station
A Three-component,short-period,telemetered station
•Three-<:omponent,broad-band station
•Central recording facility
,,·..--15 km and 30 km zones around reservoir system
I Strong motion instrumentation
located at dam sites
o 5
E=4io10
/
j /T~;;:~
/ I Susi'n.
Lake
/~g.
m Louiw
20 30 Kilometers
r!I
Figure 1
GENERAL CONFIGURATION OF THE PROPOSED SUSITNA NETWORK
30