What happened on 3/11 in Japan?
Earthquakes and tsunamis
How do they occur?
Can we predict them?
How can we mitigate the damage?
Shun-ichiro Karato
Yale University
Department of Geology & Geophysics
4/18/2020
1
Summary
• 2011 Tohoku-Kanto earthquake was the largest earthquake
in the history of Japan (4th largest in the world) (more than
~200 Billion $ damage).
• Earthquakes in the oceanic region generate tsunamis.
• Earthquakes occur due to slow motions of solid Earth
(mantle convection)  some regularities
• Earthquake occurs by faulting
• Fault properties are heterogeneous  earthquakes have
“personality”  difficulties in (short-term) prediction
• Monitoring (and interpretation in terms of models) will
help earthquake prediction in some cases.
• Short-term warning reduces the damage.
4/18/2020
2
• What happened on 3/11/2011?
• How to characterize earthquakes?
– What is the “magnitude” of an earthquake?
– How often do big quakes occur?
– How big is the 3/11 earthquake compared to others?
• Where do earthquakes occur?
• When do earthquakes occur?
• Efforts toward earthquake prediction or
forecasting
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3
HistoricalM earthquakes in Japan
Finite Fault Model
684
869
887
1096
1099
1361
1498
1611
1703
1707
1793
1843
1854
1854
1891
1896
1918
1923
1933
1946
1952
1994
2003
2011
Nankai
Tohoku (Sanriku)
Nankai
Tokai
Nankai
Nankai
Nankai-Tokai
Tohoku (Sanriku)
Kanto
Nankai-Tokai
Tohoku (Sanriku)
Tokachi (Hokkaido)
Tokai
Nankai
Nobi
Tohoku (Sanriku)
Kuril (Hokkaido)
Kanto
Tohoku (Sanriku)
Nankai
Tokachi (Hokkaido)
east-Hokkaido
Tokachi (Hokkaido)
Tohoku (Sanriku)
8.0-8.3
8.3-9.0
8.0-8.5
8.0-8.5
8.0-8.5
8.0-8.5
8.2-8.4
8.1
8.1
8.4-8.7
8.0-8.4
8.0
8.4
8.4
8.1
8.2-8.5
8.0
7.9
8.1
8.0
8.2
8.2
8.0
9.0 (9.1)
Figure 5. Surface projection of the slip distribution superimposed on GEBCO bathymetry . Red lin
[Bird, 2003]. Gray circles, if present, are aftershock locations, sized by magnitude. Y ellow circles
days, including the March 9th M 7.2 earthquake.
Slip Distribution
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SUBFAULT FORMAT
CMTSOLUTION FORMAT
4
Figure 5. Surface projection of the slip distribution superimposed on GEBCO bathymetry . Red lines indicate major pl
[Bird, 2003]. Gray circles, if present, are aftershock locations, sized by magnitude. Y ellow circles are foreshocks over
days, including the March 9th M 7.2 earthquake.
A large fault (~500
km x 150 km), more than 20 m displacement
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Slip Distribution
5
Land moved more than 3 m in some places (near Sendai).
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Shocks were felt throughout Japan.
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Tsunami （津波）
(model)
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(observations)
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• What is an earthquake?
• Why do we have earthquakes?
• What is the “magnitude” of an earthquake?
– How big was the earthquake on 3/11/2011 among
other “megaquakes”?
• How does an earthquake generate “tsunami”?
• Where do earthquakes occur, and how often?
– Earthquake prediction or forecast
• How does a seismic wave propagate?
• How can we mitigate seismic hazard?
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Seismology in Japan and in the world
•
•
•
•
•
•
•
•
•
•
•
1880: the first seismometer (Milne, Ewing) [in Japan]
1880: the first Seismological Society in the world [in Japan]
1906: San Francisco EQ  US seismology
1923: Kanto EQ  Japanese seismology (1925:
Earthquake Research Institute, University of Tokyo)
1935-1942: “magnitude” (Richter scale)
~1960: earthquake = fault motion (Honda, Maruyama)
1965:
“seismic moment” (Aki)
~1970-: focal mechanisms (Kanamori)
1972: dilatancy model of an earthquake (Scholz)
1976 “seismic tomography (CAT scan)” (Aki)
1979: classification of earthquakes (Uyeda-Kanamori)
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Earthquake Prediction Program in Japan
• 1891: Nobi earthquake “Committee on
earthquake disaster prevention”
• 1923: Kanto earthquakes  Earthquake
Research Institute
• 1962: “Earthquake Prediction Blueprint”
• 1965-1998: “Earthquake Prediction Program”
• 1999: “A New Blueprint”
– model  monitoring
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Where do earthquakes occur?
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seismic energy, which propagates radially from the earthquake source, resulting in the oscillating motion, or
shaking, recorded by seismographs stationed around the world. Check out the Animated Earthquake Guide on the
BBC webpage for graphics of earthquake mechanisms.
What is the “magnitude” of an
earthquake?
Seismic energy is released in the form of waves that are divided into two groups: body waves and surface waves.
Body waves are further divided into Primary (P) and Secondary (S) waves based on wave form. P- waves travel
fastest and are compressional -type waves, similar to sound waves. S-waves arrives more slowly and have a shearwave form. The body waves are followed by the surface waves, which have the highest recorded amplitudes and
cause the most noticeable ground shaking. Seismologists use seismometers to measure the amplitude of these
waves to estimate the amount of energy released by the earthquake. The higher the amplitude, the larger the
earthquake. Additionally, the distance between the earthquake and seismometer can be estimated by measuring the
difference between the P and S wave arrival times and using estimates of the wave velocities. When such distances
are calculated for multiple (three or more) seismometers, seismologists can determine the earthquake epicenter.
Seismogram recorded from a magnitude 6.5 earthquake in Columbia on January 19, 1995.
Image courtesy of Mark A. Horrell, Ph.D
Geologists work together with seismologists and engineers to study and understand earthquakes and the
mechanisms that produce them. Geologists map the locations of faults, evaluate when and how often large
earthquakes have occurred on the faults, and assess their probability of generating large earthquakes in the future.
Log (maximum amplitude) at a certain distance (100 km) = magnitude
http:/ / www.aegweb.org/ i4a/ pages/ index .cfm?pageid= 4074
4/18/2020
Page 1 of 5
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Google Earth KML
(requires Google Earth)
Location
Date UTC
Magnitude
Lat.
Long.
Reference
1.
Chile
1960 05 22
9.5
-38.29
-73.05
Kanamori, 1977
2.
Prince William Sound, Alaska
1964 03 28
9.2
61.02
-147.65
Kanamori, 1977
3.
Off the West Coast of Northern Sumatra
2004 12 26
9.1
3.30
95.78
Park et al., 2005
4.
Near the East Coast of Honshu, Japan
2011 03 11
9.0
38.322
142.369
PDE
5.
Kamchatka
1952 11 04
9.0
52.76
160.06
Kanamori, 1977
6.
Offshore Maule, Chile
2010 02 27
8.8
-35.846
-72.719
PDE
7.
Off the Coast of Ecuador
1906 01 31
8.8
1.0
-81.5
Kanamori, 1977
8.
Rat Islands, Alaska
1965 02 04
8.7
51.21
178.50
Kanamori, 1977
9.
Northern Sumatra, Indonesia
2005 03 28
8.6
2.08
97.01
PDE
10.
Assam - Tibet
1950 08 15
8.6
28.5
96.5
Kanamori, 1977
11.
Andreanof Islands, Alaska
1957 03 09
8.6
51.56
-175.39
Johnson et al., 1994
12.
Southern Sumatra, Indonesia
2007 09 12
8.5
-4.438
101.367
PDE
13.
Banda Sea, Indonesia
1938 02 01
8.5
-5.05
131.62
Okal and Reymond, 2003
14.
Kamchatka
1923 02 03
8.5
54.0
161.0
Kanamori, 1988
15.
Chile-Argentina Border
1922 11 11
8.5
-28.55
-70.50
Kanamori, 1977
16.
Kuril Islands
1963 10 13
8.5
44.9
149.6
Kanamori, 1977
Updated 2011 March 15
References
Johnson, J.M., Y. Tanioka, L.J. Ruff, K. Sataki, H. Kanamori, and L.R. Sykes, 1994, The 1957 great Aleutian earthquake, Pure and
Appl. Geophys., 142, 3-28.
San Francisco 1906
7.9
Kanto
1923
7.9
http:/ / earthquake.usgs.gov/
earthquakes/
Hanshin
1995world/ 10_largest_world.php
6.9
Kanamori, H., 1977, The energy release of great earthquakes, J. Geophys. Res. 82, 2981-2987.
4/18/2020
P
14
numbers
magnitude
Large earthquakes are rare.
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15
magnitude and energy
Chile (1960)
Tohoku-Kanto (2011)
[Sumatra (2004)]
San Francisco (1906)
Kanto (1923)
Hanshin (1995)
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Where and when do earthquakes occur?
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Earthquakes are generated by the stress caused by a
material circulation in the Earth (mantle convection).
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How does an earthquake occur?
How does it generate a tsunami?
500px
500px
- 500px
Eq- Eqgen1.svg.png
gen4.svg.png
- Eq- gen3.svg.png
gen2.svg.png
500
500 275
500
323
pixpix
285
319
elselspix els
4/18/2020
3/ 3/
19/
19/
113/
11
10:26
19/
10:28
11AM
10
AM
19
Tsunami propagation
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Tsunami
long
way.
Tsunami can
can propagate
be amplified
near
the coast.
20
Challenges in earthquake prediction
• A difficult problem: Many factors affect the
way in which earthquakes are generated.
– Basic causes (general models)
– Mechanics of faults
– Detailed description (monitoring)
• Long-term prediction
• Short-term prediction
– most important, most difficult
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Long-term prediction
• Classification of earthquakes
• Systematics in earthquake activities
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Where do earthquakes occur?
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23
Plate boundaries in and around Japan
front |1 |2 |3 |4 |5 |6 |7 |8 |9 |10 |11 |12 |13 |14 |15 |16 |17 |18 |19 |20 |21 |22 |23 |24 |review
Additional Supercourse lecture
A Case Study for the Setting of W
in the PAK Emergency
Earthquake & Tsunami South Asia
Earthquake Mitigation (in Spanis
THE 99 MARMARA EARTHQUAK
Spanish)
Earthquakes in Turkey
Revelation of 5.12 Quake, Sichua
Earthquake Part2. Prevention P
Short-term response after the qua
after the quake Part 5. Post-disa
long-term concern
EXPERIENCE IN THE AFTERMA
BHUJ IN INDIA
Disaster Epidemiologic lessons fro
Iran. Part I Part II Part III Part I
NEW ZEALAND EARTHQUAKE 2
CALIFORNIA EARTHQUAKE EXE
INDONESIA EARTHQUAKE, TSU
ERUPTION. Part I Part II
Indonesia Earthquake 27 May 200
4/18/2020
24
Some regularities (where?)
Seismic gap hypothesis
Mogi (1979)
4/18/2020
25
Challenges in predicting when
• There are some gross rules: seismic gaps, quasiperiodicity.
• But earthquakes do not always follow the “rules”.
 Some successes but many failures
4/18/2020
26
Successes and failures
Figure 6.
Map of the epicentral area of the 1975 Haicheng earthquake (epicenter
shown as a star) showing locations of some of the towns, communes, and other types
of population centers mentioned in the text. Thick gray curves show spatial distribution
of the intensity of the earthquake (same as in Fig. 4). Thin gray curves indicate county
boundaries. Urban areas of Yingkou City and towns of Dashiqiao (in Yingkou County)
and Haicheng (in Haicheng County) are outlined with thick solid lines.
• China (1975-1976)
– successful prediction in Haicheng 海城(1975) and
failure of prediction in Tanshang 唐山(1976)
Role of the Shipengyu Earthquake Observatory
Figure 7.
Foreshock sequence of the Haicheng
earthquake. Data are from SSB Analysis and Prediction Center (1980).
Haicheng: Clear short-term precursor,
4/18/2020
The Shipengyu Earthquake Observatory was established in 1970 near the village of Shipengyu in Yingkou
3. observatories
Epicentral of
distribution
of historical earthquakes in Tangs
County. It wasFigure
one of the
the SSB Shenyang
Brigade (i.e., Liaoning provincial Earthquake Office)
but
areas (1484-1976.7.2
8, M³4.75).
was administered by the Yingkou City government. In 1975,
it had 13 workers, operating a short-period, three-component, smoke-recorder type 64 seismograph made in China.
They also had a tilt meter, although their tilt data (shown by
Raleigh et al. 1977) were never mentioned in any precursor
discussions prior to the Haicheng earthquake. It is said that,
in the few years before the Haicheng earthquake, the observatory made and distributed over 100,000 copies of brochures and organized over 100 film or slide shows to spread
earthquake knowledge (7 – 10). After the earthquake, the
observatory was the first one of the six organizations to be
mentioned by the SSB for rendering “meritorious services in
the analysis-prediction of southern Liaoning earthquake”
(7 – 10).
In early February 1975, because the future epicenter was
only 20 km away (Fig. 6), the observatory became the most
important source
of foreshock
information
not only
for the
Figure
4. Annual
variations
of earthquake
Figure 5. E
provincial Earthquake Office but also for all other local govfrequency
in
Tangshan
and
its
surrounding
earthquakes
ernments and other earthquake offices of southern Liaoning.
areas
(Wu inKaitong,
1981). log
The foreshocks were hand
recorded
the observatory’s
book (6 – 1), which also contains accounts of various anomalies and felt and damage reports for the foreshocks that were
Tanshang: weak long-term “precursor (?)”
27
Some regularities (When? )
Parkfield, CA, USA
Earthquakes occurred regularly, but an earthquake expected in 1993
occurred in 2004.
4/18/2020
28
Sumatra
Tohoku-Kanto
Tohoku-Kanto versus Sumatra
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29
Challenges in predicting when
• There are some gross rules: seismic gaps, quasiperiodicity.
• But earthquakes do not always follow the “rules”.
– Heterogeneity in the fault structures  “personality”
in earthquakes
– Need to characterize individual faults
4/18/2020
30
A key concept in characterizing the fault:
“asperity” (stuck region)
Fault has strongly stuck regions (asperities) as well as smoothly
moving regions.  An earthquake occurs when a stuck area is broken.
4/18/2020
31
Remote sensing of fault motion
(CAT scan of a fault motion)
4/18/2020
32
Direct sampling from faults
(biopsy of a fault)
epth
rthquake Experiment,
ne 2004 to drill a deep
Fault Zone near the
hole location in relation
urface, will form a San
ctly reveal, for the first
eneration within a
d then use advanced
o angle the hole
hed on the east side.
and geophysical
ng-term monitoring
moderate earthquakes
eters during the
anical properties of
uakes, the role of
sics of earthquake
mark a major advance
hazards and
n ambitious scientific
elements of
4/18/2020
Plate Boundary
of a large
Schematic cross section of the San
Andreas Fault Zone at Parkfield,
showing the drill hole for the San
Andreas Fault Observatory at Depth
San Andreas fault (USA)
Nankai trough (Japan)
33
A large earthquake in Tohoku was expected
4/18/2020
34
How to minimize the hazard?
• Building
• Warning
– Short-term earthquake warning
– Tsunami warning
4/18/2020
35
seismic energy, which propagates radially from the earthquake source, resulting in the oscillating motion, or
shaking, recorded by seismographs stationed around the world. Check out the Animated Earthquake Guide on the
BBC webpage for graphics of earthquake mechanisms.
Seismic energy is released in the form of waves that are divided into two groups: body waves and surface waves.
Body waves are further divided into Primary (P) and Secondary (S) waves based on wave form. P- waves travel
Earthquake warning
fastest and are compressional -type waves, similar to sound waves. S-waves arrives more slowly and have a shearwave form. The body waves are followed by the surface waves, which have the highest recorded amplitudes and
cause the most noticeable ground shaking. Seismologists use seismometers to measure the amplitude of these
waves to estimate the amount of energy released by the earthquake. The higher the amplitude, the larger the
earthquake. Additionally, the distance between the earthquake and seismometer can be estimated by measuring the
difference between the P and S wave arrival times and using estimates of the wave velocities. When such distances
are calculated for multiple (three or more) seismometers, seismologists can determine the earthquake epicenter.
Seismogram recorded from a magnitude 6.5 earthquake in Columbia on January 19, 1995.
Image courtesy of Mark A. Horrell, Ph.D
Geologists work together with seismologists and engineers to study and understand earthquakes and the
mechanisms that produce them. Geologists map the locations of faults, evaluate when and how often large
earthquakes have occurred on the faults, and assess their probability of generating large earthquakes in the future.
http:/ / www.aegweb.org/ i4a/ pages/ index .cfm?pageid= 4074
4/18/2020
Page 1 of 5
36
Earthquake warning
(installed in 2006 (in Japan))
4/18/2020
37
Summary
• 2011 Tohoku-Kanto earthquake was the largest earthquake
in the history of Japan (4th largest in the world) (more than
~200 Billion $ damage).
• Earthquakes in the oceanic region generate tsunamis.
• Earthquakes occur due to slow motions of solid Earth
(mantle convection)  some regularities
• Earthquake occurs by faulting
• Fault properties are heterogeneous  earthquakes have
“personality”  difficulties in (short-term) prediction
• Monitoring (and interpretation in terms of models) will
help earthquake prediction in some cases.
• Short-term warning reduces the damage.
4/18/2020
38
4/18/2020
39
4/18/2020
40
Precursor for the Tohoku-Kanto earthquake?
4/18/2020
41
Long-term earthquake risk assessment in Japan
4/18/2020
42
Large earthquakes since 1900
Ea r t h qu a k e H a za r ds Pr ogr a m
Largest Earthquakes in the World Since 1900
Google Earth KML
4/18/2020
(requires Google Earth)
43