Mapping Earthquake Mapping Earthquake Hazard in the United Hazard in the United Hazard in the United Hazard in the United States States David M. Boore U.S. Geological Survey A talk presented to the Geology Department, Oberlin College, Oberlin, Ohio, 9 March 2004 College, Oberlin, Ohio, 9 March 2004
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Mapping Earthquake Mapping Earthquake Hazard in the UnitedHazard in the UnitedHazard in the United Hazard in the United
StatesStates
David M. BooreU.S. Geological Survey
A talk presented to the Geology Department, Oberlin College, Oberlin, Ohio, 9 March 2004College, Oberlin, Ohio, 9 March 2004
I b hIn both Canada and
the U.S., ,damaging
earthquakes areare
experienced over much of th tthe country,
making seismic hazard a
national issue
• From G. Atkinson
USGS National Seismic Hazard M 2002 U d tMaps: 2002 Update
A. Frankel, M. Petersen, C. Mueller, K Haller R Wheeler E LeyendeckerK. Haller, R. Wheeler, E. Leyendecker, R. Wesson, S. Harmsen, C. Cramer,
D Perkins and K RukstalesD. Perkins, and K. RukstalesU.S. Geological Survey
C lif i d d j i tl ithCalifornia maps produced jointly with California Geological Survey:
T Cao and W BryantT. Cao and W. Bryant
What’s Ahead?
• What is “earthquake (seismic) hazard’’?• Response spectrum: the measure of ground shaking
that is mapped • Mapping the hazard
– seismicity (with special attention to New Madrid)seismicity (with special attention to New Madrid)• where do earthquakes occur?• how often do they occur?• how large are they?
– ground motion• specify the ground shaking as a function of earthquake size
and distance from a siteti th h d l t b d– computing the hazard values to be mapped
– results• Paleoseismometry: precarious rocks
“Civilisation exists by geological consent, subject
h i h ito change without prior notice ”notice.
William Durant, historian
SEISMIC HAZARD -SEISMIC HAZARD -
the possibility of that consentthe possibility of that consent being withdrawn.g
SEISMIC HAZARDSEISMIC HAZARD is the possibility of
The hazard is controlled by NatureThe hazard is controlled by Nature.
Vulnerability and Exposure are controlled by humans.
Seismic Risk Mitigation
HAZARD * EXPOSURE * VULNERABILITY COST
Seismic Risk Mitigation
HAZARD * EXPOSURE * VULNERABILITY = COST
AAssess
ControlReduce
Control
Balance
2003 San Simeon earthquake (M 6.5): 2 deaths in Paso Robles
0 480.48g
Damage in Paso Robles, CA, due to collapse of unreinforced masonry building (2 lives lost) during the 2003 San Simeon earthquake
•Contrast damage with that in Bam Iran (M 6 6)in Bam, Iran (M 6.6)•>30,000 deaths•Why so many deaths, compared to Paso Robles?
•Was ground motion higher than in Paso Robles? (0.98g pga in Bam; 0 48g 10 km fromBam; 0.48g 10 km from Paso Robles)•Was the construction less earthquake
?resistant?
0.98gg
Measures of ground motion forMeasures of ground motion for engineering purposes
convert displacement spectrum into acceleration spectrum (multiply by (2π/T)2)
100
10
100
10
(cm
/s2 )
1
10
cem
ent
(cm
)
0 1
1
Acc
eler
atio
n
0.01
0.1
Rel
ativ
eD
ispl
ac
0 1 1 10 100
0.01
0.1
0 1 1 10 100
10-4
0.001
R
1999 Hector Mine Earthquake (M 7.1)
station 596 (r= 172 km), transverse component
0.1 1 10 100Period (sec)
0.1 1 10 100Period (sec)
pick off values of SA at 0.2 sec and 1 sec
100
10
100
10
(cm
/s2 )
1
10
cem
ent
(cm
)
0 1
1
Acc
eler
atio
n
0.2 sec 1 sec0.01
0.1
Rel
ativ
eD
ispl
ac
0 1 1 10 100
0.01
0.1
0 1 1 10 100
10-4
0.001
R
1999 Hector Mine Earthquake (M 7.1)
station 596 (r= 172 km), transverse component
0.1 1 10 100Period (sec)
0.1 1 10 100Period (sec)
fit functions through values to form an approximate response spectrump p
100
10
100
SA = SA(0.2 s)
10
(cm
/s2 )
1
10
cem
ent
(cm
) SA = SA(1.0 s)/T
0 1
1
Acc
eler
atio
n
0.2 sec 1 sec0.01
0.1
Rel
ativ
eD
ispl
ac
0 1 1 10 100
0.01
0.1
0 1 1 10 100
10-4
0.001
R
1999 Hector Mine Earthquake (M 7.1)
station 596 (r= 172 km), transverse component
similarity of SA(0.2) and SA(1.0) a coincidence here!
0.1 1 10 100Period (sec)
0.1 1 10 100Period (sec)
y ( ) ( )
U.S. National Seismic Hazard Map – 2002 Edition
U.S. National Seismic Hazard Map – 2002 Edition
Some Major Uses of the National SeismicSome Major Uses of the National Seismic Hazard Maps and Associated Products
• Building codes: International Building Code, International Residential Code, ASCE national design load standard, NEHRP ProvisionsD i f hi h b id d l dfill• Design of highway bridges, dams, landfills
• Loss estimation (e.g., HAZUS), earthquake iinsurance
• Emergency management, EQ scenarios
USGS Seismic Hazard Maps (1996 andUSGS Seismic Hazard Maps (1996 and update in 2002)
• Consensus of experts: regional workshops (CEUS 1995, 2000), external review panel, open review of interim maps on Internet
• Average hazard estimate, not worst case; d lt ti d ti di tiused alternative ground-motion prediction
equations and fault locations; uncertainty estimates published in 1997 2000 2001estimates published in 1997, 2000, 2001
Probabilistic Seismic Hazard Analysis (PSHA)
•• SeismicitySeismicity: for each spatial point, assign the probability of an earthquake with particular magnitude occurring each yearearthquake with particular magnitude occurring each year (consider all magnitudes in a range from small to large).
•• Ground motionGround motion: for a spatial point, compute the probability that a level of ground motion will be exceeded considering alla level of ground motion will be exceeded, considering all surrounding points as potential sources (each magnitude and distance can be thought of as a scenario).
Combine probabilities to obtain a frequency of exceedance for• Combine probabilities to obtain a frequency of exceedance for each scenario.
• Add frequencies of exceedance for a particular level of ground ( )motion (combining all scenarios). This gives the HAZARD HAZARD
CURVECURVE
S i i itS i i itSeismicitySeismicity
1. Identify the potential sources of future earthquakes
2. Estimate the maximum magnitude (Mmax) earthquake that ld ithi hcould occur within each source
3. Calculate the recurrence relationship that defines how frequently, on average, earthquakes of different magnitude q y g q goccur within each source.
Divide the US into WUS and CEUS
S A d f lt C i Pl iSan Andreas fault– Carrizo Plain(taken from a radio-controlled kite; see http://quake.usgs.gov/kap/carrizo/)
Faults (Fairview Valley, NV)
Note the flimsy cabin and stovepipe; does this say anything about the strength of ground shaking?
Intraplate Earthquakes
• The driving forces, and stress fields, that are characterized by intraplate earthquakes are difficult to characterize and vary widely
• One example mechanism for intraplate h k i i d i h l i learthquakes is stress associated with post-glacial
reboundSt t ti d k “f il d” ift• Stress concentrations and weak “failed” rifts another possibility
Specification of seismicityseismicity for the National Seismic Hazard MapsSeismic Hazard Maps
• 1 Use spatially-smoothed historic seismicity;1. Use spatially smoothed historic seismicity; assumes that moderate and large earthquakes will occur near previous M3+ events
• 2. Use large background zones based on broad geologic criteria; addresses non-stationary seismicity; quantifies hazard in areas with littleseismicity; quantifies hazard in areas with little historic seismicity but potential for damaging earthquakes
• 3. Use specific fault sources with recurrence rates determined from geologic slip rates, trenching st dies or paleoliq efaction datesstudies, or paleoliquefaction dates
Direct Inputs to Hazard Maps
• Earthquake catalogs (instrumental and historic)• Fault data (geologic slip rates, dates of past (g g p , p
events from trenching, fault geometry, etc.)• Effects of prehistoric earthquakes: p q
paleoliquefaction (New Madrid, Charleston, Wabash Valley), subsidence and uplift (Cascadia, Seattle flt)
• Geodetic data (NV-CA, Puget Lowland)
Stein
Note linear pattern of New Madrid
seismicity – but no f f l isurface faulting
found
New Madrid seismicity believed related to buried riftNew Madrid seismicity believed related to buried rift faults (under several km of overlying sediments)
The Smoking Guns for New Madrid EarthquakesEarthquakes
• 1811-12: three largest earthquakes felt as far away N E l d d i i i 9 10 ias New England, producing intensity 9-10 in
Memphis, very large liquefaction area• between 1300 and 1600 A D : sequence of three• between 1300 and 1600 A.D.: sequence of three
large earthquakes with similar liquefaction area as 1811-12 (Tuttle and Schweig)
• between 800 and 1000 A.D.: sequence of three large earthquakes with similar liquefaction area as 1811 12 (Tuttle and Schweig)1811-12 (Tuttle and Schweig)
• also: M6.6 earthquake in 1895 in Charleston, MO; M6 in 1843 in Marked Tree, AR; history of M5.1M6 in 1843 in Marked Tree, AR; history of M5.1 and smaller events since 1900
response-spectrum ordinate (at a particular frequency)
f ti f kA
ccel
(g)
e:06
:53:
50
as a function of magnitude distance, site conditions, and perhaps other
0.1
rizon
talP
eak
ND
NR
.dra
w;
Dat
e:20
04-0
3-08
;Tim
e
perhaps other variables.
Larg
erH
o
1992 Landers M = 7 3
File
:C:\m
etu_
03\re
gres
s\B
JFLN
0.01
1992 Landers, M = 7.31994 NR, M=6.7 (reduced by RS-->SS factor)Boore et al., Strike Slip, M = 7.3, NEHRP Class D_+
10-1 1 101 102
Shortest Horiz. Dist. to Map View of Rupture Surface (km)
Deriving the Equations
• Regression analysis of observed data if have adequate observations (rare for most of the world).
• Regression analysis of simulated data for regions with inadequate data (making use of motions from
ll if il bl i dismaller events if available to constrain distance dependence of motions).H b id th d t i l ff t• Hybrid methods, capturing complex source effects from observed data and modifying for regional differencesdifferences.
8Western North America
Observed data adequate
6
7
entM
agni
tude
Obse ed data adequatefor regression exceptclose to large ‘quakes
5
6
Mom
e
Used by BJF93 for pga 3-09
-05;
Tim
e:14
:40:
01
1 10 100 10008
Eastern North America
_wna
_ena
_pga
.dra
w;
Dat
e:20
03
6
7
entM
agni
tude
File
:C:\m
etu_
03\re
gres
s\m
_d_
Observed data not adequate for regression,
5
6
Mom
e
AccelerographsS i hi St ti
use simulated data
1 10 100 1000Distance (km)
Seismographic Stations
Higher ground motions for given Magnitude, Distance for CEUS Earthquakes Compared with
WUS• Higher Q in crust: less attenuation with distance• Higher earthquake stress drop: more high-frequency
ground motion for specified moment magnitudeground motion for specified moment magnitude• Determined from instrumental analysis of small and
moderate events in CEUS and isoseismals of large ghistoric events
Distance-decay of regional shear waves determinedby Benz, Frankel, and Boore (1997)
Fits using magnitude-independent stress drop, omega –2 model
From Frankel (1994)
T = 0.2 sec
1
ion
(g)
M = 7.6
0.1
ectra
lAcc
eler
at
M = 5.6
0.01Spe
ENA: Atkinson and Boore, 1995ENA: Frankel et al., 1996WNA: Boore et al, 1997
10 20 30 100 2000.001
Distance (km)
How do we estimate ground motions for large earthquakes near New Madrid?
• use estimated magnitude to calculate ground motions f i d ti di ti tifrom various ground-motion prediction equations: stochastic models using source parameters and derived for small earthquakes; constant stress drop with magnitude model validated with felt area vs magnitudemagnitude model validated with felt area vs. magnitude data; in 2002 added two corner frequency model, hybrid extended-source model, and semi-empirical modelAtki d B (1998) d di ti ith• Atkinson and Boore (1998) compared predictions with regional ENAM data
• check with recorded ground motions of Bhuj, India earthquake
Hazard Methodology ExampleExample
a bEarthquake SourcesGround motion
r1
Hazard curvea
erat
ion
d1
d2
d3
d4
r1
r2
high seismicityM 7.6
k gr
ound
acc
elM7.6
r3
high seismicityzone
peak ground acceleration (pga)0.25gdistancepe
ak
0.5g
(AfterAnnual probability that earthquake occurs:
Source B 1/200=0.005
Source A Site
1/10=0.10
After Wang et al., 2003
2T=0.2 sec
1
POE = 0.16
POE = 0.50
"POE"= Probability of Exceeding the value of SA
0.1
0.2
SA
(g)
POE = 0.84
0
M = 5.5
1 2 10 20 1000.02
Distance (km).
2T=0.2 sec
1
POE = 0.16
POE = 0.50
"POE"= Probability of Exceeding the value of SA
0.44g
0.1
0.2
SA
(g)
POE = 0.840.26g
0.16g
0
M = 5.5
1 2 10 20 1000.02
Distance (km).
2T=0.2 sec
1
POE = 0.16
POE = 0.50
"POE"= Probability of Exceeding the value of SA
0.44g
0.1
0.2
SA
(g)
POE = 0.840.26g
0.16g
0
M = 5.5
"FOE"= Frequency of Exceedance (combining eq & sa prob)
For 0.44g, FOE = 0.10*0.16 = 0.016
1 2 10 20 1000.02
Distance (km).
2T=0.2 sec
1
POE = 0.16
POE = 0.50
"POE"= Probability of Exceeding the value of SA
0.44g
0.1
0.2
SA
(g)
POE = 0.840.26g
0.16g
0
M = 5.5
"FOE"= Frequency of Exceedance (combining eq & sa prob)
Brune, 2000Near Antelope Valley fault, Walker, California (Brune, 2000)
Near Antelope Valley fault, Walker, California (Brune, 2000)
Q asi static toppling force F mg tanQuasi-static toppling force: F = mg tan α
Anooshehpoor et al., 2004
Anooshehpoor et al., 2004
Anooshehpoor et al., 2004
Anooshehpoor et al., 2004
Anooshehpoor et al., 2004
Anooshehpoor et al., 2004
Anooshehpoor et al., 2004
Anooshehpoor et al., 2004
Anooshehpoor et al., 2004
Preliminary Conclusions from Study ofPreliminary Conclusions from Study of Precarious Rocks
• Strong asymmetry in ground shaking from reverse faults (low on footwall side, high on hanging wall side)side)
• Ground motions for normal faults smaller than predicted by standard equationspredicted by standard equations
• Ground motions near San Andreas fault in S. California smaller than shown by hazard maps (!)
SUMMARYSUMMARY
• Defined hazard• Described response spectra • Basis for hazard maps: seismicity• Basis for hazard maps: ground motion• Mapping hazard
R l• Results• Paleoseismometry: precarious rocks
Stacy and Dave studying geology in the Dolomites, Italy, in January during Winter term
?
Brune, 2000
Anooshehpoor et al., 2004
ENA: Atkinson and Boore, 1995ENA: Frankel et al., 1996
T = 1.0 sec
1
ion
(g)
,WNA: Boore et al, 1997
M = 7.6
0.1
ectra
lAcc
eler
at
M = 5.6
0.01Spe
10 20 30 100 2000.001
Distance (km)
ConclusionsConclusions
• USGS hazard maps are based on consensus of h d i fexperts; represent average hazard estimates from
alternative models; best maps for policy and design decisionsdesign decisions
• USGS hazard maps are derived from observations of past earthquakes in NM (1811-12, about 1500 and 900 A.D.), historical seismicity, geology, and models of ground motions for the region that have been validated with observed ground motions andbeen validated with observed ground motions and intensities
• Design maps need to have consistent rules for g pentire U.S.
GeologyGeologySeismic historySeismic history
EarthquakeEarthquakeL M d lL M d lSeismic historySeismic history
Earthquake SourcesEarthquake SourcesLoss ModelLoss Model
Gives mean and standard deviation of response-deviation of responsespectrum ordinate (at a particular frequency) as a f ti f it dfunction of magnitude distance, site conditions, and perhaps other variables.
(E. Field)
1.0)
eak
Acc
el(g
)
06;T
ime:
14:2
6:36
0.1
Hor
izon
talP
\BJF
LND
NR
.dra
w;
Dat
e:20
03-0
9-0
Larg
er
1992 Landers, M = 7.31994 NR M=6 7 (reduced by RS >SS factor)
File
:C:\m
etu_
03\re
gres
s\
1 1 2
0.01
1994 NR, M=6.7 (reduced by RS-->SS factor)BJF, Strike Slip, M = 7.3, NEHRP Class DBJF, + - \5s
10-1 1 101 102
Shortest Horiz. Dist. to Map View of Rupture Surface (km)
8Western North America
Observed data adequate
6
7
ntM
agni
tude
Obse ed data adequatefor regression exceptclose to large ‘quakes
5
6
Mom
e
Used by BJF93 for pga -05;
Tim
e:14
:41:
02
1 10 100 1000
Used by BJF93 for pga
8World
na_b
jf_pe
er_p
ga.d
raw
;D
ate:
2003
-09
7
ntM
agni
tude
File
:C:\m
etu_
03\re
gres
s\m
_d_w
n
New recordings help fill in lack of data close to large ‘quakes (but can data be
5
6
Mom
en
PEER NGA (preliminary)
Includes1999 Chi-Chi (M 7.6)1999 Kocaeli (M 7.5)1978 Tabas (M 7.4)1986 Taiwan (M 7.3)1999 D (M 7 1)