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Earthquake Effects 1
Earthquakes: Cause and Effect
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Earthquake Effects 2
Fundamentals of Earthquake Engineering
Earthquakes: Cause and Effect
Why Earthquakes Occur
How Earthquakes are MeasuredEarthquake EffectsMitigation Strategy
Earthquake Time Histories
Revised 2/8/05
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Earthquake Effects 3
Seismic Activity >M5 Since 1980
Ring of Fire
Mid-Atlantic Ridge
Alpide Belt
Alpide Belt
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Earthquake Effects 4
Crustal Plate Boundaries
Plate Boundaries
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Earthquake Effects 5
Plate Tectonics: Driving Mechanism
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Earthquake Effects 6
Continental-Continental collision
(orogeny)
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Earthquake Effects 7
Oceanic-Continental Collision
(subduction)
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Earthquake Effects 8
San Andreas Fault System
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Earthquake Effects 9
Seismicity of North America
1811 New Madrid
M > 8.01886 Charleston
M > 7.0
Pacific
Plate
North American
Plate
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Earthquake Effects 10
Faults and Fault Rupture
Fault plane
Hypocenter
(focus)
Epicenter
Rupture surface
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Earthquake Effects 11
Types of Faults
Strike Slip(Left Lateral)
Strike Slip(Right Lateral)
Normal Reverse (Thrust)
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Earthquake Effects 12
New Fence
Time = 0 Years
Elastic Rebound Theory
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Earthquake Effects 13
Old Fence
New Road
Time = 40 Years
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Earthquake Effects 14
Old Fence
Time = 41 Years
New Road
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Earthquake Effects 15
San Andreas Fault Offset - 1906 S.F. EQ M8.2
fault trace
2.6-m fence offset
from fault
Photo credit: USGS.
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Earthquake Effects 16
Seismic Wave Forms
(Body Waves)
Compression Wave(P Wave)
Directiono
f
Propagation
Shear Wave
(S Wave)
Directionof
Propagatio
n
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Earthquake Effects 17
Love Wave Rayleigh Wave
Seismic Wave Forms
(Surface Waves)
Directionof
Propagation
Directionof
Propagation
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Earthquake Effects 18
Love WavesP Waves S Waves
Arrival of Seismic Waves
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Earthquake Effects 19
Effects of Seismic Waves
Fault Rupture
Ground ShakingLandslides
LiquefactionTsunamis
Seiches
Surface Fault Rupture;
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Earthquake Effects 20
Surface Fault Rupture;1999 Chi Chi Taiwan Earthquake (M7.7)
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Earthquake Effects 21
If a saturated sand is subjected to groundvibrations, it tends to compact and decrease in volume.
If drainage is unable to occur, the tendency todecrease in volume results in an increase inpore pressure.
If the pore water pressure builds up to the point atwhich it is equal to the overburden pressure, the
effective stress becomes zero, the sand loses itsstrength completely, and liquefaction occurs.
Liquefaction
Seed and Idriss
Liquefaction Field of Sand Boils
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Earthquake Effects 22
Liquefaction - Field of Sand Boils
Liquefaction damage - Niigata Japan
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Earthquake Effects 23
Liquefaction damage - Niigata, Japan
1964
L l S di
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Earthquake Effects 24
SandBoils
UnliquefiedSoil
LiquefiedSoil
mostly horizontal deformation of gently-sloping
ground (< 5%) resulting from soil liquefaction
one of most pervasive forms of ground damage;
especially troublesome for lifelines
Lateral Spreading
Liquefaction and Lateral Spreading
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Earthquake Effects 25
Liquefaction and Lateral SpreadingNishinomiya Harbor Bridge - 1995 Kobe, Japan EQ
Liquefaction and Lateral Spreading
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Earthquake Effects 26
Liquefaction and Lateral SpreadingNishinomiya Harbor Bridge - 1995 Kobe, Japan EQ
Lateral Spreading
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Earthquake Effects 27
Lateral Spreading1999 Chi Chi EQ M7.7 (Taiwan)
Landslide on Coastal Bluff
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Earthquake Effects 28
Landslide on Coastal Bluff
Loma Prieta Earthquake, California, 1989
Tsunami Damage: Seward Alaska, 1964
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Earthquake Effects 29
Banda Aceh, Indonesia
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Earthquake Effects 30
Cause of Tsunamis
Tsunamis are created by a suddenvertical movement of the sea floor.
These movements usually occur in
subduction zones.
Tsunamis move at great speeds, often 600
to 800 km/hr.
Cause of Tsunamis
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Earthquake Effects 31
Cause of Tsunamis
Cause of Tsunamis
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Earthquake Effects 32
Cause of Tsunamis
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Earthquake Effects 33
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Earthquake Effects 34
Result of Ground Shaking;
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Earthquake Effects 35
g;
1994 Northridge, California Earthquake
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Earthquake Effects 36
Earthquake effect Strategy
Fault rupture AvoidTsunami/seiche Avoid
Landslide AvoidLiquefaction Avoid/resistGround shaking Resist
Mitigation Strategies
Measuring Earthquakes
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Earthquake Effects 37
Measuring Earthquakes
INTENSITY
Subjective measure of human reaction and damage
Used where instruments are not availableVery useful in historical seismicity
MAGNITUDEMeasured with seismometersDirect measure of energy releasedPossible confusion due to different measures
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Earthquake Effects 38
Modified Mercalli Intensity
Not felt except by a few under especiallyfavorable circumstances
Felt only by a few persons at rest, especially on
upper floors of buildings. Suspended objects may swing.
Felt quite noticeably indoors, especially onupper floors of buildings. Standing automobiles mayrock slightly. Vibration like passing truck.
I.
II.
III.
Modified Mercalli Intensity
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Earthquake Effects 39
Modified Mercalli Intensity
During the day felt indoors by many, outdoors byfew. At night, some awakened. Dishes, windows,doors disturbed; walls make creaking sound. Sensation
like heavy truck striking building. Standing automobilesrocked noticeably. [0.015 to 0.02g]
Felt by nearly everyone, many awakened. Some
dishes and windows broken. Cracked plaster.Unstable objects overturned. Disturbance of trees, polesand other tall objects. [0.03 to 0.04g]
Felt by all. Many frightened and run outdoors.Some heavy furniture moved. Fallen plaster and
damaged chimneys. Damage slight. [0.06 to 0.07g]
IV.
V.
VI.
Modified Mercalli Intensity
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Earthquake Effects 40
Modified Mercalli Intensity
Everybody runs outdoors. Damage negligible inbuildings of good design and construction, slight tomoderate in well built ordinary structures, considerable
to poorly built or badly designed structures. Noticedby persons driving cars. [0.10 to 0. 15g]
Damage slight in specially designed structures,considerable in ordinary construction, great inpoorly built structures. Fall of chimneys, stacks,
monuments. Sand and mud ejected in smallamounts. Changes in well water. Persons drivingcars disturbed. [0.25 to 0.30g]
VII.
VIII.
Modified Mercalli Intensity
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Earthquake Effects 41
Modified Mercalli Intensity
Damage considerable in specially designedstructures, well designed frame structures thrownout of plumb, damage great in substantial buildings
with partial collapse. Buildings shifted off foundations.Ground cracked conspicuously. Underground pipesbroken. [0.50 to 0.55g]
Some well built wooden structures destroyed. Mostmasonry and frame structures destroyed withfoundations badly cracked. Rails bent. Landslides
considerable from river banks and steep slopes.Shifted sand and mud. Water splashed over banks.[More than 0.60g]
IX.
X.
Modified Mercalli Intensity
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Earthquake Effects 42
Modified Mercalli Intensity
Few, if any (masonry) structures left standing.Bridges destroyed. Broad fissures in ground.
Underground pipelines completely out of service.Earth slumps and land slips in soft ground.Rails bent greatly.
Damage total. Waves seen on ground surface. Linesof sight and level distorted. Objects thrown into air.
XI.
XII.
Isoseismal Map for the Giles County, Virginia
E th k f M 31 1897
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Earthquake Effects 43
Earthquake of May 31, 1897.
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Earthquake Effects 44
Isoseismal Map
from New Madrid
Earthquake
Dec. 16, 1811
1886 Charleston EQ Felt OverE t US!
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Earthquake Effects 45
Eastern US!
New York >600 mi.
Charleston
St. Louis > 650 mi.
Chicago > 700 mi.
1980 M5 2 Sharpsburg KY EQ
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Earthquake Effects 46
1980 M5.2 Sharpsburg KY EQ
Sharpsburg KY, EQdamage was $20 million
Why not New Madrid Eqsin KY? (same Iapetan-agefaults present here)
Note pattern relative toOH River
Isoseismal Map for February 9, 1971
San Fernando CA Earthquake
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Earthquake Effects 47
San Fernando CA Earthquake
Comparison of Isosiesmal Intensity for Four Earthquakes
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Earthquake Effects 48
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Earthquake Effects 49
Instrumental Seismicity
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Earthquake Effects 50
Instrumental Seismicity
ML = Log [Maximum Wave Amplitude (in mm/1000)]
Recorded Wood-Anderson Seismograph
100 km from Epicenter
Magnitude (Richter, 1935)
Richter Magnitude Also called Local Magnitude
M it d (i l)
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Earthquake Effects 51
M = Log A +f(d,h) +CS + CR
A=Wave Amplitude of seismometer needle
F(d,h) accounts for focal distance and depth
CS, CR, are Station and Regional Corrections
Magnitude (in general)
Other Wave Based Magnitudes
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Earthquake Effects 52
MS Surface-Wave Magnitude (Rayleigh Waves)
mb Body-Wave Magnitude (P Waves)
MB Body-Wave Magnitude (P and other Waves)
mbLg (Higher Order Love and Rayleigh Waves)
MJMA (J apanese, Long Period)
Other Wave Based Magnitudes
Moment Magnitude
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Earthquake Effects 53
g
Seismic Moment= MO =AD
=Modulus of RigidityA=Fault Rupture Area
D=Fault Dislocation or Slip
Moment Magnitude =MW = (Log MO-16.05)/1.5
[Units=Force times Distance]
Moment Magnitude vs. Other Magnitude Scales(Magnitude Saturation)
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Earthquake Effects 54
( g )
Approximate RelationshipBetween Magnitude and Intensity
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Earthquake Effects 55
0
1
2
3
4
5
6
7
8
9
10
1 2 3 4 5 6 7 8 9 10 11 12
Intensity
Magnitude
Richter (Local)
MbLg
Between Magnitude and Intensity
167.0 0 += IM L
66.149.0 0 += ImbLg
Seismic Energy Release
L E 15M +118
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Earthquake Effects 56
Log E = 1.5 MS+ 11.8
1E+12
1E+14
1E+16
1E+18
1E+20
1E+22
1E+24
1E+26
1E+28
0 2 4 6 8 10
Magnitude, Ms
Ene
rgy,
Ergs
..
311000
Seismic Energy Release
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Earthquake Effects 57
1E+12
1E+14
1E+16
1E+18
1E+20
1E+22
1E+24
1E+26
1E+28
0 2 4 6 8 10
Magnitude, Ms
E
nergy,
Ergs
..
Nuclear Bomb
1964 Alaska Earthquake
1906 San Francisco Earthquake
1972 San Fernando Earthquake
Atomic Bomb
1978 Santa Barbara EQ
Ground Motion Accelerograms
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Earthquake Effects 58
Sources: NONLIN (more than 100 records)
Internet (e.g. National Strong Motion Data Center) USGS CD ROM
Uses: Evaluation of Earthquake Characteristics Development of Response Spectra
Response History Analysis
Sample Ground Motion records
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Earthquake Effects 59
Ground Motion Characteristics
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Earthquake Effects 60
Ground Motion Characteristics
Acceleration, Velocity, Displacement
Effective Peak Acceleration & Velocity
Fourier Amplitude Spectra
Duration (Bracketed Duration)
Incremental Velocity (Killer Pulse)
Response Spectra
Other (See Naiemand Anderson)
400
600
Horizontal Acceleration (E-W), cm/sec2
Typical Earthquake Accelerogram Set
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Earthquake Effects 61
-600
-400
-200
0
200
0 5 10 15 20 25 30 35 40 45
-600
-400
-200
0
200
400
600
0 5 10 15 20 25 30 35 40 45
-600
-400
-200
0200
400
600
0 5 10 15 20 25 30 35 40 45
Tim e (s ec)
Vertical Acceleration, cm/sec2
Horizontal Acceleration (N-S), cm/sec2
Time, Seconds Loma Prieta Earthquake
-463 cm/sec2
-500 cm/sec2
-391 cm/sec2
Definition of Bracketed Duration
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Earthquake Effects 62
-600
-400
-200
0
200
400
600
0 5 10 15 20 25 30 35 40 45
Bracketed Duration
0.05g
Time, Seconds
Acceleration, cm/sec2
Definition of Incremental Velocity
600
Acceleration, cm/sec2
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Earthquake Effects 63
Time, Seconds
-400
-300
-200
-100
0
100
200
300
400
8 9 10 11 12
-600
-400
-200
0
200
400
600
0 5 10 15 20 25 30 35 40 45
Acceleration, cm/sec2
Time, Seconds
Concept of Fourier Amplitude Spectra
)2()2i ()2()(2/2/ 2/ NN N
jfAjfbjf
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Earthquake Effects 64
-600
-400
-200
0
200
400
600
0 5 10 15 20 25 30 35 40 45
Acceleration, cm/sec2
N points at timestep dt
0.0
0.2
0.4
0.6
0.8
1.0
1.2
0 10 20 30
Frequency (Hz)
N/2points at frequencydf
Acceleration, cm/sec2
)2cos()2sin()2cos()(1
001 1
000 jj
j
j j
jjg jfAajfbjfaatv
== =++=++
22jjj baA +=Ndtdff /10 ==
=
j
j
ja
barctan
Ground Motion Frequency Content (1)
1.2
HORIZONTAL Acceleration (E W) cm/sec2
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Earthquake Effects 65
-600
-400
-200
0
200
400600
0 10 20 30 40 50
-600
-400
-200
0
200
400
600
0 10 20 30 40 50
0.0
0.2
0.4
0.6
0.8
1.0
1.2
0 5 10 15 20 25 30
Frequency(Hz)
F
ourierAmplitude
0.0
0.2
0.4
0.6
0.8
1.0
1.2
0 5 10 15 20 25 30
Frequency (Hz)
Fou
rierAm
plitude
HORIZONTAL Acceleration (E-W), cm/sec2
VERTICAL Acceleration, cm/sec2
Time, Seconds
Development of an Elastic Displacement
Response Spectrum
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Earthquake Effects 66
-0.40
-0.20
0.00
0.20
0.40
0.00 1.00 2.00 3.00 4.00 5.00 6.00
TIME, SECONDS
GROUND
ACC
,g
T=2.0 Seconds
T=0.6 Seconds
El Centro Earthquake Record
Maximum Displacement Response Spectrum
-4.00
-2.00
0.00
2.00
4.00
0.00 1.00 2.00 3.00 4.00 5.00 6.00DISPLACEMEN
T,
in.
-8.00
-4.00
0.00
4.00
8.00
0.00 1.00 2.00 3.00 4.00 5.00 6.00DISPLACEMENT
,In.
0
2
4
6
8
10
12
14
16
0 2 4 6 8 10
PERIOD, Seconds
DISPL
ACEMENT,
inches
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