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1813141516171818 1314151613 17141516 17
SURFACE-FAULT-RUPTURE HAZARD ZION NATIONAL PARK GEOLOGIC-HAZARD STUDY AREA
EXPLANATION
T 38 ST 39 S
37 30'
113 7' 30"
2010
DISCUSSION
USING THIS MAP
MAP LIMITATIONS
SYMBOLS
Earthquakes occur without warning and can cause injury and death, major economic loss, and social disruption(Utah Seismic Safety Commission, 1995). An earthquake is the abrupt, rapid shaking of the ground caused bysudden slippage of rocks deep beneath the Earth’s surface. The rocks break and slip when the accumulatedstress exceeds the rock’s strength. The surface along which the rocks slip is called a fault. Large earthquakes(>M 6.5) are commonly accompanied by surface faulting. The rupture may affect a zone tens to hundreds of feetwide and tens of miles long. Surface faulting on normal faults produces ground cracking and typically one ormore “fault scarps.” When originally formed, fault scarps have near-vertical slopes and, depending on the size ofthe earthquake, can range from a few inches to many feet high. Local ground tilting and graben formation bysecondary (antithetic) faulting may accompany surface faulting, resulting in a zone of deformation along the faulttrace tens to hundreds of feet wide. Surface faulting, while of limited aerial extent when compared to otherearthquake-related hazards such as ground shaking and liquefaction, can have serious consequences forstructures or other facilities that lie along or cross the fault rupture path (Bonilla, 1970). Buildings, bridges, dams,tunnels, canals, and pipelines have all been severely damaged by surface faulting (see, for example, Lawson,1908; Ambraseys, 1960, 1963; Duke, 1960; California Department of Water Resources, 1967; Christenson andBryant, 1998; USGS, 2000).The hazard due to surface faulting is directly related to the activity of the fault—that is, how often the faultruptures the ground surface and how likely it is to rupture in the future (Christenson and Bryant, 1998). Becausedesigning a structure to withstand surface faulting is generally considered impractical from an economic,engineering, and architectural standpoint for most structures (Christenson and others, 2003; Bryant and Hart,2007), avoiding active fault traces is the recommended approach for mitigating surface-faulting hazards.Effectively avoiding surface faulting requires conducting a site-specific investigation to (1) identify all potentiallyactive faults at a site, (2) assess the level of activity of the faults, and (3) establish appropriate setback distancesfrom the fault(s).
In California, the Alquist-Priolo Earthquake Fault Zoning Act (Bryant and Hart, 2007), which regulatesdevelopment along known active faults, defines an “active” fault as one that has had “surface displacement withinHolocene time (about the past 11,000 years).” Because California has a well-recognized earthquake hazard andwas the first state to implement regulations designed to mitigate those hazards, the California “Holocene”standard has found its way into many regulations in other parts of the country, even in areas where the Holoceneis not the best time frame against which to measure surface-faulting recurrence. dePolo and Slemmons (1998)argued that in the Basin and Range Province, a time period longer than the Holocene is more appropriate fordefining active faults, because most faults there have surface-faulting recurrence intervals (average repeat times)that approach or exceed 10,000 years. They advocate a late Pleistocene age criterion, specifically 130,000years, to define active faults in the Basin and Range Province. They base their recommendation on theobservation that six to eight (>50%) of the 11 historical surface-faulting earthquakes in that region were on faultsthat lacked evidence of Holocene activity but had evidence of late Pleistocene activity.Because of the difficulties in using a single “active” fault definition, the Western States Seismic Policy Council(WSSPC) has defined the following fault activity classes (WSSPC Policy Recommendation 08-2, 2008; firstadopted in 1997 as WSSPC Policy Recommendation 97-1, and revised and readopted in 2002, 2005, and 2008[WSSPC, 2008]):
Christenson and Bryant (1998) and Christenson and others (2003) recommended adopting the WSSPC faultactivity-class definitions in Utah, and we follow that recommendation in this study.For additional information about surface faulting and other earthquake-related hazards in the Zion National ParkGeologic-Hazard Study Area, refer to the Earthquake Hazards chapter in this report.
Well-defined Holocene-active (movement within the past 10,000 years [11,500 cal yr B.P.]) orsuspected Holocene-active fault: surface-fault-rupture-hazard investigation recommended for all IBCOccupancy Category II, III, and IV buildings and other structures (International Code Council, 2009a).Buried or approximately located Holocene-active or suspected Holocene-active fault: surface-fault-rupture-hazard investigation recommended for all IBC Occupancy Category II, III, and IV buildingsand other structures (International Code Council, 2009a).Well-defined fault with unknown activity level: paleoseismic data are lacking, recommend treating asa Holocene-active fault until proven otherwise.Buried or approximately located fault with unknown activity level: paleoseismic data are lacking,recommend treating as a Holocene-active fault until proven otherwise.Well-defined suspected late-Quaternary- or Quaternary-active fault: normal fault related to the currentregional extensional tectonic regime overlain by an unfaulted mid- or late-Quaternary basalt flow >100,000 years old; the most recent surface-faulting earthquake is older than the age of the overlyingbasalt, but how much older is unknown. Surface-fault-rupture-hazard investigation recommended forIBC Occupancy Category III and IV buildings and other structures (International Code Council,2009a). Studies for other structures designed for human occupancy remain prudent for faultsdemonstrated to be late-Quaternary active (movement within the past 130,000 years), but should bebased on an assessment of whether risk-reduction measures are justified by weighing the probabilityof occurrence against the risk to lives and potential economic loss. Studies for other structuresintended for human occupancy for faults demonstrated to be Quaternary active (movement within thepast 1,800,000 years) are optional because of the low likelihood of surface faulting, although surfacerupture along the fault is still possible.Buried or approximately located suspected late-Quaternary- or Quaternary-active fault: normal faultrelated to the current regional extensional tectonic regime overlain by an unfaulted mid- or late-Quaternary basalt flow > 100,000 years old; the most recent surface-faulting earthquake is older thanthe age of the overlying basalt, but how much older is unknown. Surface-fault-rupture-hazardinvestigation recommended for IBC Occupancy Category III and IV buildings and other structures(International Code Council, 2009a). Studies for other structures designed for human occupancyremain prudent for faults demonstrated to be late-Quaternary active (movement within the past130,000 years), but should be based on an assessment of whether risk-reduction measures arejustified by weighing the probability of occurrence against the risk to lives and potential economicloss. Studies for other structures intended for human occupancy for faults demonstrated to beQuaternary active (movement within the past 1,800,000 years) are optional because of the lowlikelihood of surface faulting, although surface rupture along the fault is still possible.Surface-fault-rupture-hazard special-study area. The special-study areas established for well-definedfaults extend for 500 feet on the downthrown side and 250 feet on the upthrown side of each fault.We classified normal faults as well defined if UGS 1:24,000-scale mapping shows them as solidlines, indicating that they are recognizable as faults at the ground surface. Because their location isuncertain, the surface-fault-rupture-hazard special-study areas around buried or approximatelylocated faults are broader, extending 1000 feet on each side of the suspected trace of the faults.
ByWilliam R. Lund, Tyler R. Knudsen, and David L. Sharrow
HAZARD REDUCTION
Plate 4Utah Geological Survey Special Study 133
Zion National Park Geologic-Hazard Study Area, Washington and Kane Counties, Utah
Camp
Creek
Creek
Horse RanchMountain
Taylor Fork
North
Fork
Middle
Fork
South
LeePass
NaguntMesa
BuckPastureMountain
Creek
Timber
Kolob
CanyonsRoad
ShuntaviButte
GregoryButte
KolobArch Langston
Mountain
Creek
La Verkin
WillisCreek
BEAR CANYONTRAP
KO
LO
B
CA
NY
ON
S
BurntMountain
HO P
VA L L E Y
FirepitKnoll
PineValleyPeak
NorthgatePeaks
NorthGuardian
Angel
SouthGuardianAngel
Kolob
Terrac
eRo
ad
Kolob
Terrace
Road
North
Creek
Right
Fork
Left
Fork
Blue
Creek
Goose
Creek
LavaPoint
Kolob
Creek
DeepCr
eek
Coalp
itsWa
sh
Wash
Scoggins
Altar ofSacrifice
The WestTemple
MeridianTower The
Sentinel
MountKinesava
Wash
Hube
r
Creek
Oak
The Watchman
JohnsonMountain FORK
EAST
RIVER
VIRGIN
P A R U N U W E A P
C A N Y O N
BridgeMountain
The EastTemple
MountSpry
CraterHill
TwinBrothers
Mountainof the Sun
The GreatArch
The GreatWhite Throne
LadyMountain
CastleDome
Mount
AngelsLanding
ObservationPoint
Mountainof Mystery
WynopitsMountain
IvinsMountain
Timber
HU
RR
I CA
NE
CL I
FF
S
Death Point
Tucupit Point
Paria Point
Beatty Point
Top
Mountain
Herbs
Po
intLA
NGST
ON
CANYO
N
Currant
Creek
Cane
Creek
POLE
CANYON
L OW
E R
K OL O
B
P L A T E A U
UP P E R
K OL O
B
P L A T E A U
HO
RS
EP A
ST
UR
E
PL A
TE
AU
ZI O
N
CA
NY
ON
O R D E R V I L L E C A N Y O N
TheSubway
GREAT
WEST
CANYON
COUG
A R MO U N TA I N
CourtPatriarchsTheof
CreekBirch
Creek
Pine
Creek
Pine
Creek
Clear
Chec
kerbo
ard
Mes
a
Creek
Clear Creek
Co-op
GIFFORDCANYON
FORK
NORTH
RIVE
R
VIRGIN
ZION-MOUNT CARMEL TU NN EL
TUNNEL
Wash
Terry Wash
Jennin
gs
Wash
Coalpits
TheBishopric
HEAPS
CANYON
ECHO
CANYON
CableMountain
Temple ofSinawava
TELEPHONE
CANYON
IMLAY
CANYON
BULLOCH
GULC
HT H E
N A R R OWS
FORK
NORT
H
RIVER
VIRGIN
WILDCAT
CANYON
RUSSELLGULCH
North
Creek
North
Creek
Zion
Cany
on
Scen
icDr
ive
9
9
The Grotto
Zion CanyonVisitor Center
ZionLodge
Little
Creek
Grapevine
Wash
TOW
E RS
V I R G I NT H E
O F
Abraham Isaac
Jacob
ChurchMesa
PHANTOM VALLEY
CORRAL
HOLLOW
KolobCreek
WeepingRock
Cathedral Mountain
Majestic
Kolob CanyonsVisitor Center
WASH
INGT
ON C
OKA
NE C
O
IRON COWASHINGTON CO
Neag
le R
idge
BullpenMountain
Pocket Mesa
OAK SPRING VALLEY
PINE
VALLEYLEE
VALLEY
CaveKnoll
CAVE
VALLEY
TabernacleDome
Wash
SpringPine
TRAIL
CANYONGrea
theart
Mesa
BEHUNIN
CANYON
Creek
Shunes
Shunesburg Mountain
Wash
Hepworth
Wash
DennettCanyon
Bee HivePeak
HIDDENCANYON
CANYON
MYSTERY
R 12 W R 11 W
T 38 ST 39 S
R 11 W R 10 W
T 40 ST 41 S
T 41 ST 42 S
T 39 ST 40 S
T 41 ST 42 S
T 39 ST 40 S
T 40 ST 40.5 S
T 41 ST 42 S
R 11 W R 10 W
R 10 W
R 12 W R 11 W
R 10 W R 9.5 W R 9.5 W R 9 W
37 27' 30"
37 25'
37 22' 30"
37 20'
37 17' 30"
37 15'
37 12' 30"
37 10' 37 10'
37 12' 30"
37 15'
37 17' 30"
37 20'
37 22' 30"37 22' 30"
37 25'
113 5'
113 2' 30"
113
37 22' 30"
112 57' 30" 112 55'
112 52' 30"
112 52' 30"
112 55'112 57' 30"
113
113 2' 30"113 5'
113 7' 30"
113 10'
113 12' 30"
113 12' 30"
Zion National Park Geologic-Hazard Study Area boundaryZion National Park boundaryCounty boundaryState highwayMinor roadFoot trailExisting park structureArea not studiedFault - see Explanation for description of color codes; balland bar on downthrown side of fault
This map shows potentially active faults along which surface faulting may occur. A special-study area is shownaround each fault, within which we recommend that a site-specific, surface-fault-rupture-hazard investigation beperformed prior to construction. These investigations can resolve uncertainties inherent in generalized hazardmapping and help ensure safety by identifying the need for setbacks from the fault.The UGS Guidelines for Evaluating Surface-Fault-Rupture Hazards in Utah (Christenson and others, 2003)include a detailed rationale for performing surface-fault-rupture-hazard investigations, minimum technicalrequirements for conducting and reporting those studies, recommendations regarding when surface-fault-rupture-hazard investigations should be conducted based on fault activity class and the type of facility proposed, andprocedures for establishing safe setback distances from active faults. Zion National Park staff and others shouldrefer to the UGS guidelines regarding the details of conducting and reviewing surface-fault-rupture-hazardinvestigations.For well-defined faults color-coded red and black (Holocene and Suspected Quaternary, respectively), werecommend that surface-fault-rupture-hazard investigations be performed in accordance with the UGSguidelines. Because paleoseismic data are lacking for the orange-coded faults (fault activity class unknown), werecommend that those faults be considered Holocene active until paleoseismic studies demonstrate otherwise.Because approximately located and buried faults lack a clearly identifiable surface trace, they are not amenableto trenching, which is the standard surface-fault-rupture-hazard investigation technique used to study well-defined faults (McCalpin, 2009). Where development is proposed in a special-study area for a buried orapproximately located fault, we recommend that, at a minimum, the following tasks be performed to better definethe surface-fault-rupture hazard in those areas:
Review of published and unpublished maps, literature, and records concerninggeologic units, faults, surface and ground water, previous subsurfaceinvestigations, previous geotechnical and geophysical investigations, and otherrelevant factors.Stereoscopic interpretation of aerial photographs to detect any subtle fault-relatedfeatures expressed in the site topography, vegetation or soil contrasts, and anylineaments of possible fault origin.Field evaluation of the proposed site and surrounding area to observe pertinentsurface evidence for faulting, including mapping of geologic units as necessary todefine critical geologic relations; evaluation of geomorphic features such as springsor seeps (aligned or not), sand blows or lateral spreads, or other evidence ofearthquake-induced features; and excavation of test pits to evaluate the age of thedeposits onsite to constrain the time of most recent surface faulting.
1.
2.
3.
This map is based on 1:24,000-scale geologic mapping, and the inventory of potentially active faults obtainedfrom that mapping and shown on this map reflects that level of detail. Some smaller faults may not have beendetected during the mapping or faults may be concealed beneath young geologic deposits. Additionally,approximately located and buried faults by definition lack a clearly identifiable surface trace, and therefore theirlocation is less well known. Site-specific fault-trenching investigations should be preceded by a careful fieldevaluation of the site to identify the surface trace of the fault, other faults not evident at 1:24,000-scale, or otherfault-related features at a site-specific scale.
Because surface faulting is typically confined to relatively narrow zones along the surface trace of a fault, earlyrecognition and avoidance are the most effective strategies for mitigating this hazard. Once the activity class ofthe fault is determined (see Activity Classes section above), we recommend that setbacks from the fault traceand any associated zone of deformation be established in accordance with UGS guidelines for evaluatingsurface-fault-rupture hazards in Utah (Christenson and others, 2003). Carefully locating all potentially active faulttraces at a site, assessing their level of activity and amount of displacement, establishing an appropriate setbackdistance from the fault, and proper facility and site design remain the most reliable procedures for mitigatingdamage and injury due to surface faulting. Considering the proximity of the Kolob Entrance Station andassociated buildings to the surface trace of the Hurricane fault, we recommend that a reconnaissance surface-fault-rupture-hazard investigation be conducted for those facilities. If the reconnaissance shows that a surface-rupture hazard may exist, we recommend a follow-up trenching investigation to fully assess the hazard.In Utah, earthquake-resistant design requirements for construction are specified in the seismic provisions of theIBC (International Code Council, 2009a) and IRC (International Code Council, 2009b), which are adoptedstatewide. IBC Section 1803.5.11 requires that an investigation be conducted for all structures in Seismic DesignCategories C, D, E, or F (see the Earthquake Ground-Shaking Hazard section in chapter 5) to evaluate thepotential for surface rupture due to faulting.
37 27' 30"
EAST
COUGAR
MOUNTAIN
FAULT
MOUNTAIN
COUGAR
WEST
SCOGGINSWASHFAULTS
FAUL
T
MESA
GRAF
TON
EAST COUGARMTN FAULT
WildcatCanyon
Fault
UNNAMEDFAULT
BEAR TRAPCANYON FAULT
HURRICANEFAULT ZONE
FAULT
If the results of these investigations reveal evidence of possible surface-faulting-related features, those featuresshould be trenched in accordance with the UGS guidelines for evaluating surface-fault-rupture hazards in Utah(Christenson and others, 2003). Following the above-recommended studies, if no evidence of surface faulting isfound, development at the site can proceed as planned. However, we recommend that construction excavationsand cut slopes be carefully examined for evidence of faulting as development proceeds.
UTAH GEOLOGICAL SURVEYa division of Utah Department of Natural Resourcesin cooperation withNational Park Service
ACTIVITY CLASSES
Holocene fault – a fault that has moved within the past 10,000 years (11,500 cal yr B.P.) and has beenlarge enough to break the ground surface.Late Quaternary fault – a fault that has moved within the past 130,000 years and has been large enough tobreak the ground surface.Quaternary fault – a fault that has moved within the past 1,800,000 years and has been large enough tobreak the ground surface.
Approximate meandeclination, 2009
12 9'o
TRUE
NOR
THMA
GNET
IC N
ORTH
WEST COUGARMTN FAULT
UNNAMEDFAULT
BEAR TRAPCANYON FAULT
UNNAMEDFAULT
UNNAMEDFAULTS
This geologic-hazard map was funded by the Utah Geological Survey and theU.S. Department of the Interior, National Park Service. The views andconclusions contained in this document are those of the authors and should notbe interpreted as necessarily representing the official policies, either expressedor implied, of the U.S. Government.Although this product represents the work of professional scientists, the UtahDepartment of Natural Resources, Utah Geological Survey, makes no warranty,expressed or implied, regarding its suitability for a particular use. The UtahDepartment of Natural Resources, Utah Geological Survey, shall not be liableunder any circumstances for any direct, indirect, special, incidental, orconsequential damages with respect to claims by users of this product.For use at 1:24,000 scale only. The Utah Geological Survey does notguarantee accuracy or completeness of data.
www.geology.utah.gov
Base map consists of U.S. Department of Agriculture 2006 National AgriculturalImagery Program natural color aerial photography and shaded relief generatedfrom digital elevation data acquired from the Utah Automated GeographicReference Center.
Universal Transverse Mercator Projection, zone 12North American Datum of 1983
REFERENCESAmbraseys, N.N., 1960, On the seismic behavior of earth dams: Proceedings of the Second World Conference
Ambraseys, N.N., 1963, The Buyin-Zara (Iran) fault earthquake of September 1962, a field report: Seismological
Bonilla, M.G., 1970, Surface faulting and related effects, in Wiegel, R.L., coordinating editor, Earthquake
Bryant, W.A., and Hart, E.W., 2007, Fault-rupture hazard zones in California – Alquist-Priolo earthquake fault
California Department of Water Resources, 1967, Earthquake damage to hydraulic structures in California:
Christenson, G.E., Batatian, L.D., and Nelson, C.V., 2003, Guidelines for evaluating surface-fault-rupture hazards
Christenson, G.E., and Bryant, B.A., 1998, Surface-faulting hazard and land-use planning in Utah, in Lund, W.R.,
dePolo, C.M., and Slemmons, D.B., 1998, Age criteria for active faults in the Basin and Range Province, in Lund,
Duke, C.M., 1960, Foundations and earth structures in earthquakes: Proceedings of the Second World
International Code Council, 2009a, International building code: Country Club Hills, Illinois, 678 p.
International Code Council, 2009b, International residential code for one- and two-family dwellings: Country Club
Lawson, A.C., editor, 1908, The California earthquake of April 18, 1906, Report of the state Earthquake Investigation
McCalpin, J.P., 2009, Paleoseismology (second edition): San Diego, Academic Press, 613 p.U.S. Geological Survey, 2000, Implications for earthquake risk reduction in the United States from the Kocaeli,
Utah Seismic Safety Commission, 1995, A strategic plan for earthquake safety in Utah: Salt Lake City, Utah Seismic
Western States Seismic Policy Council, 2008, WSSPC Policy Recommendation 08-2 – Active fault definition for the
on Earthquake Engineering, Tokyo and Kyoto, Japan, v. 1, p. 331-358.
Society of America Bulletin, v. 53, p. 705-740.
engineering: Englewood Cliffs, New Jersey, Prentice-Hall, Inc., p. 47-74.
zoning act with index to earthquake fault zone maps (Interim revision 2007): Online,<http://www.consrv.ca.gov/dmg/>, accessed June 1, 2009.
California Department of Water Resources Bulletin 116-3, 200 p.
in Utah: Utah Geological Survey Miscellaneous Publication 03-6, 16 p.
editor, Proceedings volume, Basin and Range Province Seismic-Hazards Summit: Utah Geological SurveyMiscellaneous Publication 98-2, p. 63-73.
W.R., editor, Proceedings volume, Basin and Range Province Seismic-Hazards Summit: Utah GeologicalSurvey Miscellaneous Publication 98-2, p. 74-83.
Conference on Earthquake Engineering, Tokyo and Kyoto, Japan, v. 1, p. 435-455.
Hills, Illinois, 870 p.
Commission (Volume 1): Carnegie Institution of Washington Publication No. 87, v. 1, 254 p.
Turkey earthquake of August 17, 1999: U.S. Geological Survey Circular 1193, 64 p.
Safety Commission, 64 p.
Basin and Range Province: Online, Western States Seismic Policy Council,<http://www.wsspc.org/PublicPolicy/PolicyRecs/2008/Adopted_PR08-2_BRFaultDef.pdf>, accessed April 26,2008.
Map Location
1 0 10.5 MILE1000 0 1000 2000 3000 4000 5000 6000 7000 FEET
1 0 10.5 KILOMETER
SCALE 1:24,000
