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1
Dr. Abdelrahman Abueladas
Lecture 7
Faculty of EngineeringCivil Engineering
Engineering Geology
CE
Dr. Abdelrahman Abueladas Civil Engineering Class Engineering Geology Lecture 7
Earthquake
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Turkey, 1999
Earthquake
arthquake
2Dr. Abdelrahman AbueladasCivil Engineering Class
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Dr. Abdelrahman Abueladas Civil Engineering Class Engineering Geology Lecture 7
What is an Earthquake? An earthquake is the vibration, sometimes violent, o the
Earth!s sur ace that ollo"s a release o energy in the Earth!scrust.
Caused by volcanic activity, meteorite im#acts, undersealandslides , e$#losions o nuclear bombs or most commonly, bymovement o the Earth across a ault
Fault % racture in the Earth across "hich the t"o sides moverelative to each other
Stresses build u# until enough to cause roc&s to racture andshi t, sending o "aves o
seismic energy, elt as earth'ua&e
(
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Dr. Abdelrahman Abueladas Civil Engineering Class Engineering Geology Lecture 7
Faults are com#le$ )ones o brea&age "ith irregularsur aces, many miles "ide and long
*tress builds u# until rupture occurs at "ea& #oint
and #ro#agatesalong ault sur ace
+oint "here ru#ture
irst occurs ishypocenter or ocus +oint directly above
hy#ocenter on sur aceis epicenter
-
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*eismic "aves radiate rom the focus #oint o theinitial movement or sli# on the ault. /he epicenter is the geogra#hic #oint on the earth!s sur ace above
the ocus.
Earthquake the sha&ing or vibration o the groundoccurs "hen roc& suddenly brea&s along a ault
Dr. Abdelrahman Abueladas Civil Engineering Class Engineering Geology Lecture 70
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Types of Seismic waves1 !o"y waves#
$rimary waves %$ 1 /he astest traveling "aves.2 Com#ressional "ave travel.
( +article motion is #arallel to the#ro#agation direction o the"ave ront.
Secon"ary Waves %S *hear "aves.2 *lo"er than + "aves.( +article motion is #er#endicular to the
#ro#agation direction o the"ave ront.
- * "aves do not travel in luids.
' Surface waves#+ro#agate near the earth sur ace.
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Compressional Wave (P-Wave) Animation
1 !o"y waves#(& $rimary waves %$ 1 /he astest traveling "aves.2 Com#ressional "ave travel.
( +article motion is #arallel to the #ro#agation direction o the"ave ront.Dr. Abdelrahman Abueladas Civil Engineering Class Engineering Geology Lecture 7
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Shear Wave (S-Wave) Animation
((& Secon"ary Waves %S *hear "aves.2 *lo"er than + "aves.( +article motion is #er#endicular to the #ro#agation directiono the "ave ront.
- * "aves do not travel in luids.Dr. Abdelrahman Abueladas Civil Engineering Class Engineering Geology Lecture 7
3
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a) Rayleigh Wave (R-Wave) Animation
' Surface waves#+ro#agate near the earth sur ace
Dr. Abdelrahman Abueladas Civil Engineering Class Engineering Geology Lecture 74
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b) Love Wave (L-Wave) Animation
+article motion is hori)ontal and #er#endicular to the direction o#ro#agation 5transverse .
Am#litude decreases "ith de#th. 6aterial returns to its original sha#e a ter "ave #asses.
Dr. Abdelrahman Abueladas Civil Engineering Class Engineering Geology Lecture 71
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Focus
Mantle
SeismographCore S P
S u r f a c e w a v e s
Dr. Abdelrahman Abueladas Civil Engineering Class Engineering Geology Lecture 711
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Focus
Mantle
SeismographCore S P
S u r f a c e w a v e s
Seismic waves travel through Earth and over itssurface.
Dr. Abdelrahman Abueladas Civil Engineering Class Engineering Geology Lecture 712
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)evelopment of Seismology *eismology% study o earth'ua&es Earliest earth'ua&e device% China, 1(2 8.C. 9nstruments to detect earth'ua&e "aves% seismometers 9nstruments to record earth'ua&e "aves% seismographs Ca#ture movement o Earth in three com#onents% north
south* east west an" vertical
:ne #art stays as stationary as#ossible "hile Earth vibrates%heavy mass i$ed by inertia in
rame that moves "ith the Earth,and di erences bet"een#osition o the rame and themass are recorded digitally
Dr. Abdelrahman Abueladas Civil Engineering Class Engineering Geology Lecture 71(
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Waves# +mplitu"e % dis#lacement Wavelength % distance bet"een successive
"aves
$erio" % time bet"een "aves 5; 1< re'uency Frequency % number o "aves in one second
5her), =)
)evelopment of Seismology
Dr. Abdelrahman Abueladas Civil Engineering Class Engineering Geology Lecture 71-
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Spring
Mass
Seismograph
Dr. Abdelrahman Abueladas Civil Engineering Class Engineering Geology Lecture 710
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Spring
Mass
The mass is looselycoupled to Earth.
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Recordingpen
Earthmoves up
Dr. Abdelrahman Abueladas Civil Engineering Class Engineering Geology Lecture 717
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Recordingpen
Earthmoves up
Upward movement of the Earth causesdownward relative movement of the mass andvice versa.
Dr. Abdelrahman Abueladas Civil Engineering Class Engineering Geology Lecture 713
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Earth
moves down
Dr. Abdelrahman Abueladas Civil Engineering Class Engineering Geology Lecture 714
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Earthmoves down
The pen traces thedifferences in motion.
Dr. Abdelrahman Abueladas Civil Engineering Class Engineering Geology Lecture 72
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Earthmoves left
Earthmoves right
Earthmoves sideto side
Mass
!inge
Dr. Abdelrahman Abueladas Civil Engineering Class Engineering Geology Lecture 721
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Minutes
Surface waves
"
P S
#" $" %" &" '"
Seismogram
Dr. Abdelrahman Abueladas Civil Engineering Class Engineering Geology Lecture 722
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Minutes
Surface waves
The waves travel at different speeds and arrive atthe seismograph at different times.
"
P S
#" $" %" &" '"
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Seismograph
FocusSeismograph
Seismograph
Epicenter
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Seismograph
FocusSeismograph
Seismograph
Epicenter
Seismic waves arrive at distantseismographic stations at differenttimes.
Dr. Abdelrahman Abueladas Civil Engineering Class Engineering Geology Lecture 720
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(istance traveled from earth)ua*e epicenter +*m,
T i m e e
l a p s e
d a
f t e r s t a r t o
f e a r t
h ) u a
* e
+ m i n ,
%-minuteinterval at#'"" *m
$""" &""" """ /""" #" """
$'
$"
Seismogram0
##-minuteinterval at/ "" *m/-minute
interval at' "" *m
#'
#"
'
"
Seismogram1
SeismogramC
S wave
P wave
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(istance traveled from earth)ua*e epicenter +*m,
T i m e e
l a p s e
d a
f t e r s t a r t o
f e a r t
h ) u a
* e
+ m i n ,
%-minuteinterval at#'"" *m
$""" &""" """ /""" #" """
$'
$"
Seismogram0
##-minuteinterval at/ "" *m/-minute
interval at' "" *m
#'
#"
'
"
Seismogram1
SeismogramC
S wave
P wave
1ecause P waves travel faster than S waves theinterval 2etween their travel-time curves
increases with distance.
Dr. Abdelrahman Abueladas Civil Engineering Class Engineering Geology Lecture 727
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(istance traveled from earth)ua*e epicenter +*m,
T i m e e
l a p s e
d a
f t e r s t a r t o
f e a r t
h ) u a
* e
+ m i n ,
%-minuteinterval at#'"" *m
$""" &""" """ /""" #" """
$'
$"
Seismogram0
##-minuteinterval at/ "" *m/-minute
interval at' "" *m
#'
#"
'
"
Seismogram1
SeismogramC
S wave
P wave
1ecause P waves travelfaster than S waves theinterval 2etween theirtravel-time curves
increases with distance.
1y matching the o2servedinterval to the curves wecan determine the distancefrom the station to the
epicenter.
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#'"" *m#'"" *m0011
' "" *m' "" *m
/ "" *m/ "" *m
CC
3f we then draws a circle around eachseismographic station 4
Dr. Abdelrahman Abueladas Civil Engineering Class Engineering Geology Lecture 724
3f we then draws a circle around each
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#'"" *m#'"" *m0011
EpicenterEpicenter
' "" *m' "" *m
/ "" *m/ "" *m
CC
3f we then draws a circle around eachseismographic station 4
the point at which the circles intersect is the earth)ua*e5s
epicenter .Dr. Abdelrahman Abueladas Civil Engineering Class Engineering Geology Lecture 7(
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0mplitude6$% mm
Richtermagnitude
0mplitude+mm,
3 n t e r v a
l 2 e
t w e e n
S a n
d P w a v e s
+ s ,
( i s t a n c e
+ * m
,
P S
S-wave interval 6 $& secondsP-wave
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0mplitude6$% mm
Richtermagnitude
0mplitude+mm,
3 n t e r v a
l 2 e
t w e e n
S a n
d P w a v e s
+ s ,
( i s t a n c e
+ * m
,
P S
S-wave interval 6 $& secondsP-wave
0 seismologistmeasures theamplitude ofthe largest
seismicwave4
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0mplitude6$% mm
Richtermagnitude
0mplitude+mm,
3 n t e r v a
l 2 e
t w e e n
S a n
d P w a v e s
+ s ,
( i s t a n c e
+ * m
,
P S
S-wave interval 6 $& secondsP-wave
0 seismologistmeasures theamplitude of thelargest seismic
wave4
4and the timeinterval 2etween
the P- and S-wavesto determine thedistance from theepicenter.
Dr. Abdelrahman Abueladas Civil Engineering Class Engineering Geology Lecture 7((
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0mplitude6$% mm
Richtermagnitude
0mplitude+mm,
3 n t e r v a
l 2 e
t w e e n
S a n
d P w a v e s
+ s ,
( i s t a n c e
+ * m
,
P S
S-wave interval 6 $& secondsP-wave
0 seismologistmeasures theamplitude of thelargest seismic
wave4
4and the timeinterval 2etween
the P- and S-wavesto determine thedistance from theepicenter.
1y connecting thepoints the seismologist determines theRichter magnitude.
Dr. Abdelrahman Abueladas Civil Engineering Class Engineering Geology Lecture 7(-
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,agnitu"e >is actually a measurement o theground dis#lacement 5or #article dis#lacementobtained rom a seismogram. /he grounddis#lacement is the same as the am#litude o theseismic "ave and hence the larger the "avemotion, the greater the magnitude.?
-ichter magnitu"e >/he magnitude o any shoc&is ta&en as the logarithm o the ma$imum traceam#litude, e$#ressed in microns, "ith "hich thestandard short-period torsion seismometer "ouldregister that shoc& at an e#icentral distance o1 &m>
Dr. Abdelrahman Abueladas Civil Engineering Class Engineering Geology Lecture 7(0
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Intensity scale -- a scale forestimate earthquake shaking
based on the destructiveeffects and damage.
Mercalli scale . Invented by
Giuseppe Mercalli in 190 !this scale uses theobservations of the people"ho e#perienced the
earthquake to estimate itsintensity.
Giuseppe Mercalli (FromWalker, 1982)
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ARTHQUAK INT NSITY vs. MAGNITUD
Earth'ua&e intensity measures the e ect on #eo#le and buildings@sed to assess historical and archaeological records
Dr. Abdelrahman Abueladas Civil Engineering Class Engineering Geology Lecture 7(7
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Seismographicstations
Fault
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First motion +pulltoward epicenter,
First motion +pulltoward epicenter,
-Dr. Abdelrahman AbueladasCivil Engineering Class
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First motion +pulltoward epicenter,
First motion +pulltoward epicenter,
First motion+push awayfrom epicenter,
First motion+push awayfrom epicenter,
Dr. Abdelrahman Abueladas Civil Engineering Class Engineering Geology Lecture 7-1
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Dr. Abdelrahman Abueladas Civil Engineering Class Engineering Geology Lecture 7-2
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Tsunami generation
Thrust fault
S h a l l o w
w a t e r
Tsunami formation/sunami is a a#anese "ord "ith the English translation,>harbor "ave.>
Dr. Abdelrahman Abueladas Civil Engineering Class Engineering Geology Lecture 7-(
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Tsunami generation
Thrust fault
S h a l l o w
w a t e r
0n earth)ua*e producesa surge of water that movesoutward as a tsunami.
0 tsunami is only a fewcentimeters high in the deepocean 2ut can increase tomany meters high close toshore.
Dr. Abdelrahman Abueladas Civil Engineering Class Engineering Geology Lecture 7
--
Tsunami pr !u"e! #$
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Tsunami pr !u e! #$earthquake !isp%a"ement &
"ean &% r.
(mportant points#(n "eep ocean* tsunami has small amplitu"e an"travels with spee" of .et airliner/When approaching lan"* spee" slows an" amplitu"eincreases "ramatically/
Dr. Abdelrahman Abueladas Civil Engineering Class Engineering Geology Lecture 7
-0
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Tsunami wave propagation characteristics note that as water depth becomes shallower, waves slow down, become shorter wavelength,
and have larger amplitude
NOAA
Dr. Abdelrahman Abueladas Civil Engineering Class Engineering Geology Lecture 7
-
Computer simulation of tsunami radiation
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Dr. Abdelrahman Abueladas Civil Engineering Class Engineering Geology Lecture 7
Computer simulation of tsunami radiation.
!awaii
& hr &$ min
7orth
0merica
7orth
0mericaEpicenter
Main tsunami "ave reaches $a"aiian Islands about %.& hours after theearthquake.
-7
#a% Seismi" Ha'ar! Assessment (r )ram *GSHA(+
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Dr. Abdelrahman Abueladas Civil Engineering Class Engineering Geology Lecture 7
-3http://www.seismo.ethz.ch/gshap/
/he Global *eismic =a)ard Assessment +rogram 5G*=A+ "as launched in 1442 by the 9nternationalLithos#here +rogram 59L+ "ith the su##ort o the 9nternational Council o *cienti ic @nions 59C*@ , andendorsed as a demonstration #rogram in the rame"or& o the @nited Bations 9nternational Decade orBatural Disaster eduction 5@B
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Liquefaction is defined as 'the transformation of a granularmaterial from a solid state into a liquefied state as aconsequence of increased pore-"ater pressure'
Figure 1 - (ketch of a packet of "ater-saturated sand grains illustrating the process ofliquefaction. (hear deformations )indicated by large arro"s* induced by earthquakeshaking distort the granular structure causing loosely packed groups to collapse asindicated by the curved arro" (Youd, 1992).
Dr. Abdelrahman Abueladas Civil Engineering Class Engineering Geology Lecture 7
Liquefaction
-4
Liquefaction
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Dr. Abdelrahman Abueladas Civil Engineering Class Engineering Geology Lecture 7
Li'ue action is one o the most im#ortant and com#le$to#ics in geotechnical earth'ua&e engineering.
Li'ue action occurs "hen saturated soils lose theirstrength and a##ear to lo" as luids "hen sha&en byearth'ua&e "aves 5 Seed and Idriss, 1982; Kramer,
1996 ./he strength o the soil shrin&s to the #oint "here it isunable to hold structures or remain stable.
/he damage caused by li'ue action include slo#eailures, bridge and building oundation ailures, andlotation o buried structures.
Liquefaction
0
+here are several factors that may affect the liquefaction
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Dr. Abdelrahman Abueladas Civil Engineering Class Engineering Geology Lecture 7
here are several factors that may affect the liquefactionsusceptibility of soil deposits such as,
1- epth and thickness of the strata.
- elative density! grain si/e.- ge of sediments.%- 2resence of overlying non-liquefiable layers.&- +he previous seismic history (Seed, 1979; Seed and driss, 1982; !"ermeier and #ond,1999).
+here are three conditions must e#ist for liquefaction tooccur,
)1* (oil susceptible to liquefaction.) * (hallo" ground"ater table.) * (trong ground shaking.
01
/he ty#es o sediments most susce#tible to
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Dr. Abdelrahman Abueladas Civil Engineering Class Engineering Geology Lecture 7
yli'ue action are saturated silt and san" de#osits. 9 the silt and sand sediments are overlain by a
nonli'ue iable stratum such as clay, the li'ue actionsusce#tibility "ill be very high.6ost commonly, li'ue action initiates at de#thsbet"een ' and 0 m belo" the ground sur ace, but itcan also initiate at de#ths u# to 2 m or even more (Seedand Idriss, 1982) .
Li'ue action usually occurs at the same location
"hen the soil and ground "ater conditions haveremained unchanged.
/he li'ue action distance is #ro#ortional "ith theearth'ua&e magnitude.
02
,etho"s of the +nalyses
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Dr. Abdelrahman Abueladas Civil Engineering Class Engineering Geology Lecture 7
, y
*everal ield tests are usually used or the evaluation oli'ue action resistance o sandy soils, including%1 /he standard #enetration test 5*+/ .2 /he cone #enetration test 5C+/ .( /he 8ec&er #enetration test 58+/ .- *hear "ave velocity measurement 5 s .
0(
/he #oint based susce#tibilityusing combined scheme based on
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Dr. Abdelrahman Abueladas Civil Engineering Class Engineering Geology Lecture 7
using combined scheme based ona##lying a +GA o .(g integratedin the study area.5Abueladas, 2 1-
0-
Relation bet een Risk and Hazard
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3arthquake scientists and engineers make an important conceptualdistinction bet"een ha/ard and risk.
Hazard is the property of an earthquake that causes loss of life ordamage
Risk is the probability of loss of life! in4ury! or damage
Relation bet een Risk and Hazard
Risk ! Hazard " #ulnerability " $"posure $a/ard is the frequency of a level of shaking )liquefaction!
landslide! fault rupture* 5ulnerability measures the likelihood that something like a
building "ill be damaged 3#posure is the number of people! buildings! structures that are
e#posed to the ha/ard. +his is called an inventory. %eologists and seismologists define t&e eart&quake &azard $ngineers 'builders( masons( etc.) reduce t&e risk by decreasing t&e
*ulnerability of structures to ground motion 00
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