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Susitna-Watana Hydroelectric Project Document
ARLIS Uniform Cover Page
Title:
Site-specific seismic hazard study, Study plan Section 16.6 : Initial study
report
SuWa 207
Author(s) – Personal:
Author(s) – Corporate:
Prepared by MWH [and] Fugro
AEA-identified category, if specified:
Draft initial study report
AEA-identified series, if specified:
Series (ARLIS-assigned report number):
Susitna-Watana Hydroelectric Project document number 207
Existing numbers on document:
Published by:
[Anchorage : Alaska Energy Authority, 2014]
Date published:
February 2014
Published for:
Alaska Energy Authority
Date or date range of report:
Volume and/or Part numbers:
Study plan Section 16.6
Final or Draft status, as indicated:
Draft
Document type:
Pagination:
iv, 15 p.
Related work(s):
Pages added/changed by ARLIS:
Notes:
All reports in the Susitna-Watana Hydroelectric Project Document series include an ARLIS-
produced cover page and an ARLIS-assigned number for uniformity and citability. All reports
are posted online at http://www.arlis.org/resources/susitna-watana/
Susitna-Watana Hydroelectric Project
(FERC No. 14241)
Site-Specific Seismic Hazard Study
Study Plan Section 16.6
Initial Study Report
Prepared for
Alaska Energy Authority
Prepared by
MWH / Fugro
February 2014 Draft
INITIAL STUDY REPORT SITE-SPECIFIC SEISMIC HAZARD STUDY (16.6)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page i February 2014 Draft
TABLE OF CONTENTS
Executive Summary ..................................................................................................................... iv
1. Introduction ....................................................................................................................... 1
2. Study Objectives................................................................................................................ 1
3. Study Area ......................................................................................................................... 2
4. Methods and Variances in 2013 ....................................................................................... 2
4.1. Methods................................................................................................................... 2
4.1.1. General ............................................................................................ 2
4.1.2. Review of Project Documentation .................................................. 3
4.1.3. Variances......................................................................................... 3
4.1.4. Seismic Hazard Analysis ................................................................ 3
4.1.5. Variances......................................................................................... 4
4.2. Long-Term Earthquake Monitoring System ........................................................... 4
4.2.1. Variances......................................................................................... 4
4.3. Preliminary Reservoir Triggered Seismicity .......................................................... 5
4.3.1. Variances......................................................................................... 5
5. Results ................................................................................................................................ 5
5.1. Review of Project Documentation .......................................................................... 6
5.2. Preliminary PSHA .................................................................................................. 6
5.3. Crustal Seismic Source Assessment ....................................................................... 6
5.4. Seismic Monitoring ................................................................................................. 7
5.5. Preliminary Reservoir Triggered Seismicity .......................................................... 7
6. Discussion........................................................................................................................... 8
7. Completing the Study ....................................................................................................... 8
8. Literature Cited ................................................................................................................ 8
9. Figures ................................................................................................................................ 9
INITIAL STUDY REPORT SITE-SPECIFIC SEISMIC HAZARD STUDY (16.6)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page ii February 2014 Draft
LIST OF FIGURES
Figure 16.6-1. Regional Faults (Csejtey et al. 1978; Plafker et al. 1994; Williams and Galloway
1986) ....................................................................................................................................... 10
Figure 16.6-2. Regional Seismicity Map showing AEIC data from 1898-2010. ........................ 11
Figure 16.6-3. Earthquake Events Recorded by Project Long-Term Seismic Monitoring System,
inception through September 30, 2013. X-axis is latitude and y-axis is longitude. Red
epicenters are < 30km deep and blue are >30km depth. Magenta circle is Watana dam site.
Green triangles are seismograph stations. ............................................................................... 12
Figure 16.6-4. Depth of Earthquake Events Recorded by Long-Term Seismic Monitoring
System, November 16, 2012, through September 30, 2013. Location of cross section A-A’
(NW-SE) shown in Figure 16.6-3. .......................................................................................... 13
Figure 16.6-5. Relationship between depth and volume of reservoir for reported cases of
Reservoir Triggered Seismicity (RTS). .................................................................................. 14
Figure 16.6-6. Example of lineament mapping and analysis along the Denali Fault using IFSAR
data, 46 miles north of the Dam Site. ...................................................................................... 15
INITIAL STUDY REPORT SITE-SPECIFIC SEISMIC HAZARD STUDY (16.6)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page iii February 2014 Draft
LIST OF ACRONYMS, ABBREVIATIONS, AND DEFINITIONS
Abbreviation Definition
AEA Alaska Energy Authority
AEIC Alaska Earthquake Information Center
BOC Board of Consultants
CMS Conditional Mean Spectra
DSHA Deterministic Seismic Hazard Assessment
FERC Federal Energy Regulatory Commission
GMPE Ground Motion Prediction Equations
INSAR Interferometric Synthetic Aperture Radar
ILP Integrated Licensing Process
ISR Initial Study Report
LiDAR Light Detection and Ranging
PSHA Probabilistic Seismic Hazard Assessment
RTS Reservoir Triggered Seismicity
SPD study plan determination
UHS Uniform Hazard Spectra
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FERC Project No. 14241 Page iv February 2014 Draft
EXECUTIVE SUMMARY
Site-Specific Seismic Hazard Study (16.6)
Purpose The objectives of this study are to identify potential seismic hazards and
conduct deterministic and probabilistic seismic hazard evaluation in order to
estimate earthquake ground motion parameters at the Project site and develop
seismic design criteria for the Project
Status Field data collection and desk-top studies have begun; however, certain
elements of the field investigation evaluation of crustal seismic sources have
not been completed. Field activities included aerial reconnaissance and
geologic mapping. Preliminary Probabilistic Seismic Hazard Analysis
(PSHA) and Reservoir Triggered Seismic Analysis (RTS) studies have been
completed. In the next field season, the crustal seismic source evaluation, with
a focus in the dam site area, which will included aerial surveys, on the ground
geologic mapping and if necessary, trenching, will be completed. Thereafter
the project specific seismic hazard analysis will be updated.
Study
Components
The key study methods include review of scientific literature, Interferometric
Synthetic Aperture Radar (INSAR) and Light Detection and Ranging
(LiDAR) datasets, and lineament analysis in order to identify potential
seismic hazards, field reconnaissance and mapping of potential fault features,
monitor and review earthquake event data for the Project area, obtain shear
wave velocity measurements of bedrock, development of a PSHA including
ground motions for design.
2013 Variances Land access restrictions in 2013 limited ground studies on Cook Inlet
Regional Working Group (CIRWG) lands. This restriction largely impacted
on the ground field activities, (e.g., geologic mapping, shallow pits and
sampling). Also new LiDAR imagery being obtained for other studies near
the dam site area was not obtained because of weather. New field techniques
were implemented to measure shear wave velocities.
Steps to
Complete the
Study
As explained in the cover letter to this draft ISR, AEA’s plan for completing
this study will be included in the final ISR filed with FERC on June 3, 2014.
Highlighted
Results and
Achievements
A long-term earthquake monitoring network has been established and data on
events is being collected and is being used to define the thickness of the crust
and depth to the subducting North American Plate. Over the past year, 1507
earthquakes were recorded within a region roughly 50 miles east-west by 30
miles north-south, all below magnitude 4.0. Preliminary seismic hazard and
reservoir triggered seismicity assessments have been completed and will be
updated following completion of the crustal seismic source assessment and
utilization of earthquake event data. Initial results indicate that most RTS
events will have relatively small magnitudes. The crustal seismic source
characterization study is underway.
INITIAL STUDY REPORT SITE-SPECIFIC SEISMIC HAZARD STUDY (16.6)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 1 February 2014 Draft
1. INTRODUCTION
On December 14, 2012, Alaska Energy Authority (AEA) filed with the Federal Energy
Regulatory Commission (FERC or Commission) its Revised Study Plan (RSP), which included
58 individual study plans (AEA 2012). Section 16.6 of the RSP described the Site-Specific
Seismic Hazard Study. This study focuses on conducting deterministic and probabilistic seismic
hazard evaluations to estimate earthquake ground motion parameters at the Project site, assessing
the risk at the site and the loads that the Project facilities would be subject to during and
following seismic events, and proposing design criteria for Project facilities and structures
considering the risk level. RSP 16.6 provided goals, objectives, and proposed methods for data
collection regarding seismic hazards.
On February 1, 2013, FERC staff issued its study plan determination (February 1 SPD) for 44 of
the 58 studies, approving 31 studies as filed and 13 with modifications. RSP Section 16.6 was
one of the 31studies approved with no modifications.
Following the first study season, FERC’s regulations for the Integrated Licensing Process (ILP)
require AEA to “prepare and file with the Commission an initial study report describing its
overall progress in implementing the study plan and schedule and the data collected, including an
explanation of any variance from the study plan and schedule.” (18 CFR 5.15(c)(1)) This Initial
Study Report (ISR) on the Site Specific Seismic Hazard Study has been prepared in accordance
with FERC’s ILP regulations and details AEA’s status in implementing the study, as set forth in
the FERC-approved RSP (referred to herein as the “Study Plan”).
2. STUDY OBJECTIVES
The goals of this study are to conduct deterministic and probabilistic seismic hazard evaluations
to estimate earthquake ground motion parameters at the Project site, assess the risk at the site and
the loads that the Project facilities would be subject to during and following seismic events, and
propose design criteria for Project facilities and structures considering the risk level. The intent
of the study is to fulfill specific objectives including, but not limited to the following:
Identify the seismic sources along which future earthquakes are likely to occur, including the
potential for reservoir-triggered seismicity;
Characterization of the degree of activity, style of faulting, maximum magnitudes, and
recurrence information of each fault;
Develop maps and tables depicting the spatial and geometric relations of the faults and
seismic source zones together with specific distance parameters to evaluate ground motion
parameters from each source;
Assemble available historical and instrumental seismicity data for the region, including
maximum and minimum depth of events;
Determine the distance and orientation of each fault with respect to the site;
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Estimate the earthquake ground motions at the proposed dam site, updating previous studies
to include changes in practice and methodology since the 1980s;
Propose the seismic design criteria for the site;
Prepare a supporting design report that includes the seismic criteria and results of dam
stability analysis under seismic loading (this will be addressed as part of the dam analysis,
not as part of the initial seismic characterization); and
Use of Board of Consultants for independent technical review and guidance during
development of site-specific studies.
3. STUDY AREA
The study area for the seismic hazard evaluation is necessarily large in order to include
potentially significant seismic sources throughout the region. The study area encompasses
subduction-related sources (plate interface between the North American and Pacific Plates,
which was the source of the 1964 earthquake, the epicenter of which is a significant distance
south of the Project, and intraslab sources within the down-going Pacific Plate) and all applicable
Quaternary crustal seismic sources within about 62 miles (100 kilometers) of the site (Figure
16.6-1). Crustal seismic sources beyond these distances are not expected to provide significant
ground motion contributions at the dam site relative to nearby sources. A more focused study
area will include the dam site and reservoir areas. The study area will therefore include much of
the Talkeetna block and surrounding fault zones such as the Denali; Castle Mountain; Northern
Foothills fold and thrust fault zone; inferred Talkeetna fault; and Broad Pass Fault.
4. METHODS AND VARIANCES IN 2013
4.1. Methods
4.1.1. General
The study methods proceeded in accordance with Chapter 13 of the FERC Engineering
Guidelines for the Evaluation of Hydropower Projects. The site-specific seismic hazard
evaluation for assessing the seismic risks and developing the seismic design criteria in support of
licensing and detailed design included the following tasks:
Update the understanding of geologic conditions and seismo-tectonic setting for the dam site
area;
Identify and characterize the seismic sources, including detailed geologic studies and
lineament analyses;
Identify whether a fault may be encountered beneath or adjacent to the dam and assess the
activity of the feature and, if active, the likelihood for potential fault displacement or ground
offset;
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Perform a deterministic and probabilistic seismic hazard assessment in order to define
earthquake ground motions for structural analyses;
Evaluate the potential for Reservoir Triggered Seismicity (RTS);
Assess risks to Project structures and operation associated with seismic loading conditions;
and
Propose appropriate seismic design criteria.
Work on these tasks and the associated study methods are discussed below.
4.1.2. Review of Project Documentation
A review was conducted of the existing documentation, including available previous applicable
Project reports, to characterize the geologic, geotechnical, and seismic conditions in support of
feasibility and licensing studies and detailed design so as to take maximum advantage of the
large body of knowledge that already exists for the site. Documentation reviewed included work
from the seismic studies performed in the 1970s and 1980s. A geologic and geotechnical
database was developed in order to build upon the earlier studies as they pertain to the current
Project development.
4.1.3. Variances
There were no variances from this section of the Study Plan.
4.1.4. Seismic Hazard Analysis
A preliminary deterministic and probabilistic seismic hazard evaluation was undertaken to
update the seismic hazard studies from the 1980s that included an update of the site-specific
seismic source model. Initial ground motion parameters were developed based on a desk-top
study. The methods follow general guidance defined according to Chapter 13 of the Federal
Energy Regulatory Commission’s Engineering Guidelines. Once this initial task had been
completed a comprehensive study plan approach was implemented that will lead to a final
deterministic and probabilistic seismic hazard assessment (DSHA, PSHA). Subtasks include the
following:
Update evaluations of geologic, seismologic, and seismotectonic literature for the Project
study area to identify data gaps and uncertainties that may require further evaluations.
Update seismicity catalogue for evaluation of seismicity rates, depths, magnitudes, and focal
mechanisms. This includes evaluation of recent and ongoing data collected by the Alaska
Seismographic Network and augmented by the additional seismic stations installed in the
Project area as part of the long term earthquake monitoring program.
Develop a seismotectonic model that identifies and characterizes seismic sources of
engineering significance to the Project.
Conduct geologic studies using newly acquired Light Detection and Ranging (LiDAR) and
Interferometric Synthetic Aperture Radar (INSAR) datasets to aid in the identification and
evaluation of potential seismic sources and geohazards.
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Collect field geologic data for characterization of potential seismic sources and surface
displacement hazards.
Perform surface fault displacement hazard analysis to evaluate the significance (likelihood
and amount) of potential ground surface displacement from faulting in the area of the Project,
including beneath the dam, if such a feature is present.
Perform sensitivity studies on selected surface tectonic features, faults and lineaments,
identified and being considered as potential seismic sources of engineering significance on
the design of the Project.
Monitoring and detection of local earthquakes to understand the seismic hazards in the
Project area.
Results of the site-specific seismic hazard assessment studies will be documented with Project
reports.
4.1.5. Variances
The field investigations and mapping associated with the crustal seismic source evaluation were
not completed in 2013 due to land access restrictions in the area of the proposed dam site and
Stephan Lake to Watana Creek area. The LiDAR coverage was to be expanded for other studies,
which data was also to be used for this hazard study, and would include upper Watana Creek to
the north and a larger area south of Stephan Lake. The LiDAR was to be acquired in Fall 2013
however, the imagery was not obtained because of weather. In addition, a new field technique
and method was used to obtain shear wave velocity measurements at each of the seismograph
locations. A total of seven shear wave velocity measurements were obtained. In the next field
season, the crustal seismic source evaluation will be continued following which the project site
specific hazard assessment will be updated.
4.2. Long-Term Earthquake Monitoring System
The long-term earthquake monitoring system was expanded in 2013. The earthquake monitoring
system was installed to monitor earthquake activity and to record strong shaking of the ground in
the Project area during moderate to strong earthquakes. Three new 3-component broadband
stations, four 3-component strong motion stations, and a GPS station were added to the network.
The long-term earthquake monitoring system now consists of four 6-component strong motion
and broadband seismograph stations, three 3-component broadband seismograph stations, and a
single GPS station within about 31 miles of the proposed dam site. Data on seismic events in the
Project area is obtained in real-time for processing. The seismograph stations are operated as
part of the Alaska Seismographic Network by the University of Alaska. These seismograph
stations provide additional resolution on the seismicity rates and characteristics of earthquakes in
the Project area.
4.2.1. Variances
There were no variances from this section of the Study Plan.
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FERC Project No. 14241 Page 5 February 2014 Draft
4.3. Preliminary Reservoir Triggered Seismicity
The potential for reservoir triggered seismicity (RTS) to occur during and after filling of the
reservoir was evaluated. A preliminary assessment of the potential for RTS was undertaken and
includes information from the seismic hazard analysis and a review of the earthquake events
recorded by the long-term earthquake monitoring system. The attributes that were considered in
evaluating the probability of RTS include reservoir depth; reservoir volume; the tectonic stress
state; and the rock type and structure underlying the reservoir. The probabilities that are
considered are conditional and represent the total chance for RTS to occur as a result of reservoir
filling and operation. Conditional probabilities were also developed for each attribute, as well as
for all attributes combined. For the multi-attribute analysis, each attribute is considered
independently and also in a discrete-dependent model focusing on depth and volume.
Additionally, a literature review, case study, and numerical analysis was performed of RTS
based on other projects with large, deep reservoirs in order to develop an understanding of the
potential of RTS at the Susitna-Watana site.
Data from the long-term earthquake monitoring system provides a baseline of the rates and
seismological characteristics of local seismic events prior to the impoundment of the reservoir.
Seismicity data collected as part of the long-term monitoring system data collection was used to
perform seismological analyses to help define local seismotectonic characteristics. Such
analyses include development of local velocity models, focal mechanism and regional stress
analysis, analysis of spatial patterns, and relationship of seismicity to reservoir operation. The
ultimate purpose of this preliminary study is to account for possible RTS earthquakes in the
development of seismic design parameters.
4.3.1. Variances
There were no variances from this section of the Study Plan.
5. RESULTS
The results of the study to-date include:
Review of the -available documentation on the geologic, geotechnical, and seismic
conditions within the Project area from previous studies and research.
Development of an initial geological and seismotectonics database and library.
Update of 1980s-era seismic source evaluation and development of a Preliminary DSHA
and PSHA.
Expansion of the previously installed 2012 seismic monitoring system, addition of three
6-component broadband and strong motion seismographs and one GPS station at the
proposed Watana dam site.
In situ shear-wave velocity measurements at seismograph stations for development of
improved site velocity models.
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FERC Project No. 14241 Page 6 February 2014 Draft
Collection and analysis of microseismicity event data for the Project area (Figure 16.6-2
through 16.6-4).
Preliminary Reservoir Triggered Seismicity (RTS) studies.
Lineament mapping and analysis for fault studies using LiDAR and IFSAR data.
Field reconnaissance of mapped lineaments and other features using digital elevation
models for crustal seismic source evaluation. This task will be continued when site
access is obtained.
5.1. Review of Project Documentation
This task included research, compilation, and review of relevant scientific literature, studies, and
maps necessary to update the geologic and seismologic understanding of the region. This
included review of the existing seismic studies by WCC (1980; 1982) and R&M (2009) and
published literature and fault rupture maps following the 2002 Denali earthquake. This task also
included contacting technical experts in the Alaskan seismotectonics to elucidate the current
understanding of shallow crustal seismic sources and Quaternary faulting in the Talkeetna
Terrain. Based on this literature review, a geological and seismotectonics database and library
were created.
5.2. Preliminary PSHA
Based on the review of the literature and the previous studies, an updated site-specific seismic
source model was developed and preliminary ground motion parameters (based on FERC
guidelines) were developed for the Project for use in initial dam analyses. As part of the hazard
update, a new seismic source characterization model of the dam region and site was developed.
Most recent ground motion prediction equations (GMPEs) including next generation attenuation
(NGA) relationships for shallow crustal sources, and a recently developed GMPE for the
Cascadia subduction zone, were used in the probabilistic and deterministic seismic hazard
analysis for the Susitna-Watana Dam.
5.3. Crustal Seismic Source Assessment
An assessment was made of existing and additional crustal seismic sources utilizing two high-
resolution elevation datasets, a coarser resolution IFSAR dataset and a high resolution LiDAR
dataset recently made available for the Project site area. These datasets were used to identify
lineaments and faults in the Project area, within 62 miles (100 km) from the Watana dam site
(IFSAR) with a certain focus of lineament mapping within a 25 mile radius (LiDAR) around the
Watana dam site in order to strengthen confidence in the seismic source characterization. This
task includes using the more-extensive IFSAR elevation data and terrain models for a coarse
evaluation, a “second” pass in the assessing the surface faulting hazard was made using the
detailed LiDAR elevation data. After this compilation of lineament and fault features, criteria
were developed for determining significant crustal seismic source potential (e.g., rupture length
and earthquake magnitude, length – distance screening criteria) and select features were
identified for further study.
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The crustal seismic source evaluation included a field evaluation involving aerial survey and on
the ground inspection of mapped lineaments delineated during the desk-top studies. Due to land
access restrictions, with no ground access to CIRWG lands, as discussed under Subsection 4.1.5,
the field evaluation of lineaments and faults was not completed. Field reconnaissance and
mapping of the dam site and reservoir areas on lands owned by CIRWG has been delayed till the
2014 field season.
5.4. Seismic Monitoring
Over the past year, the long-term earthquake monitoring system has recorded a total of 1507
earthquakes which were located within a region roughly 50 miles east-west and 30 miles north-
south, between November 1, 2012 and September 30, 2013. The earthquake event data
developed in support of this study is available for download at http://gis.suhydro.org/reports/isr.
The earthquakes in the Project area form two distinct groups, crustal events between 0 and 25 km
depth and intermediate depth events below 30 km in the subducting Pacific plate. This can be
seen clearly in the cross-section and depth histogram plots (Figures 16.6-3 and Figure 16.6-4).
The largest earthquake within the subducting plate, a magnitude 4.0 earthquake, occurred on
January 21, 2013 at a depth of 66.4 km (40.1 miles) and located 53 km (32.6 miles) WSW of the
dam site. The largest earthquake magnitude within the crust, a magnitude 3.8, occurred on
July 24, 2013 at a depth of 11.1 km (6.9 miles) and was located 14.2 km (8.8 miles) NW of the
dam site. About 10 small aftershocks (M=0.9-2.3) were located within a few days of the 3.8
event.
Shear wave seismic velocity measurements were taken at each of the seismograph stations. The
results of the measurements ranged from 2415 ft/s to 10345 ft/s.
5.5. Preliminary Reservoir Triggered Seismicity
An assessment of the potential for the future occurrence of RTS to occur in the vicinity of the
proposed reservoir was made expanding upon the earlier study prepared by Woodward Clyde
consultants in the 1980s (WCC, 1980). The preliminary assessment and analysis of RTS is a
work in progress as additional background information from the seismic hazard studies (see
Subsection 5.3) and long-term earthquake monitoring data (see Subsection 5.4) are essential to
this study.
The location and magnitude of any future RTS event associated with the Watana Reservoir are
highly uncertain. However, empirical data suggest that most RTS events will have relatively
small magnitudes and would most likely occur within 10 years of initial reservoir filling. From
these types of observations, ICOLD (2011) and Allen (1982) suggest that maximum RTS
magnitudes may be on the order of 6.3 and 6.5, respectively. Others (USGS) have suggested
potentially a higher magnitude. At this time, the results of the crustal seismic source assessment
are needed to improve the understanding of the local geologic and seismotectonic characteristics
that are significant to RTS assessment and therefore determining a possible maximum magnitude
that could occur in the region.
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6. DISCUSSION
Progress in the overall Seismic Hazard Study Plan has been made to-date with the completion of
a preliminary DSHA and PSHA studies, preliminary RTS studies, lineament mapping for crustal
seismic source evaluation, installation of seismometers and ground motion instruments, and
analysis of seismicity data. The study also evaluated the potential effects of various scenarios
characterizing the subduction slab earthquake, and incorporated recently acquired site shear-
wave velocity information. Several of these studies are still on-going, and will provide a basis
for developing seismic criteria to support a risk-informed hazard analysis for dam design.
7. COMPLETING THE STUDY
[As explained in the cover letter to this draft ISR, AEA’s plan for completing this study will be
included in the final ISR filed with FERC on June 3, 2014.]
8. LITERATURE CITED
AEA (Alaska Energy Authority). 2012. Revised Study Plan: Susitna-Watana Hydroelectric
Project FERC Project No. 14241. December 2012. Prepared for the Federal Energy
Regulatory Commission by the Alaska Energy Authority, Anchorage, Alaska.
http://www.susitna-watanahydro.org/study-plan.
Allen, C. 1982. Reservoir-induced seismicity and public policy, California Geology, November,
248-250.
Aker, J.W. 2011. Conditional Mean Spectrum: tool for ground motion selection. Journal of
Structural Engineering. Vol. 137. No. 3. p. 322-331.
ICOLD, 2011. Committe on Seismic Aspects of Dam Design, Reservoirs and Seismicity - State
of Knowledge- Bulletin 137.
R&M, 2009. Task 1 – Seismic Setting Review. Geotechnical Memorandum.
Woodward Clyde Consultants, 1980. Interim Report on Seismic Studies at Susitna Hydroelectric
Project: Report prepared for Acres America Inc.
Woodward Clyde Consultants, 1982. Final Report on Seismic Studies for Susitna Hydroelectric
Project. Report prepared fro the Alaska Power Authority.
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9. FIGURES
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Figure 16.6-1. Regional Faults (Csejtey et al. 1978; Plafker et al. 1994; Williams and Galloway 1986)
INITIAL STUDY REPORT SITE-SPECIFIC SEISMIC HAZARD STUDY (16.6)
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Figure 16.6-2. Regional Seismicity Map showing AEIC data from 1898-2010.
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Figure 16.6-3. Earthquake Events Recorded by Project Long-Term Seismic Monitoring System, inception
through September 30, 2013. X-axis is latitude and y-axis is longitude. Red epicenters are < 30km deep and
blue are >30km depth. Magenta circle is Watana dam site. Green triangles are seismograph stations.
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Figure 16.6-4. Depth of Earthquake Events Recorded by Long-Term Seismic Monitoring System,
November 16, 2012, through September 30, 2013. Location of cross section A-A’ (NW-SE) shown in
Figure 16.6-3.
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Figure 16.6-5. Relationship between depth and volume of reservoir for reported cases of Reservoir Triggered Seismicity (RTS).
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Figure 16.6-6. Example of lineament mapping and analysis along the Denali Fault using IFSAR data, 46 miles north of the Dam Site.