JustinTime Lecture

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Just-in-Time Lecture Earthquake Tsunami South
Asia, 26 Dec 2004
By Ali Ardalan, Ronald E. LaPorte, Eugene
Shubnikov, Faina Linkov Eric K. Noji
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• What is the Disaster Supercourse?
• What is a JIT lecture?

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Mission Statement The Global Health Network Disa
ster, Network for Tsunamis is designed to
translate the best possible scholarly information
from leading researchers to educators worldwide.
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• Lecture objectives
• To provide the best possible information
• about the science of South Asian disaster

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Earthquake Tsunami South Asian

• Greatest earthquake in 40 years
• Magnitude 9.0 on Richter scale
• 150 km off W coast / N Sumatra Island /
  Indonesia
  
• Generation of disastrous
• tsunami in 11 countries
• bordering Indian Ocean

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• History of Great Earthquakes in the Region
• Along the subduction zone from
  southern Sumatra to the Andaman Islands
  
• 2000 M 7.9
• 1861 M 8.5
• 1833 M 8.7
• 1797 M 8.4

USGS
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• Magnitude 9.0 on Richter scale
• The 4th largest earthquake in the world since
  1900
  
• The largest since 1964 Alaska earthquake
• ----------
• It was felt (VIII) at Banda Aceh, (V) at Medan,
  Sumatra (II-IV) in parts of Bangladesh, India,
  Malaysia, Maldives, Myanmar, Singapore, Sri Lanka
  Thailand.

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Earthquake Strength Measures I) Magnitude
II) Intensity

• I) Magnitude
• Definition A measure of actual physical energy
  release at its source as estimated from
  instrumental observations.
  
• Scale Richter Scale
• By Charles Richter, 1936
• Open-ended scale
• The oldest most widely used

Noji 1997
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Earthquake Strength Measures
I) Magnitude II) Intensity

• II) Intensity
• Definition a measure of the felt or perceived
  effects of an earthquake rather than the strength
  of the earthquake itself.
  
• Scale Modified Mercalli (MM) scale
• 12-point scale, ranges from barely perceptible
  earthquakes at MM I to near total destruction
  at MM XII

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Magnitude versus Intensity

• Magnitude refers to the force of the earthquake
  as
  
• a whole, while intensity refers to the
  effects of an
  
• earthquake at a particular site.
• An earthquake can have just one magnitude,
  while
  
• intensity is usually strongest close to the
  epicenter
  
• is weaker the farther a site is from the
  epicenter.
  
• The intensity of an earthquake is more germane
  to
  
• its public health consequences than its
  magnitude.

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• Duration of the Earthquake
• Actual rupture duration 3- 4 min.
• Definition The time it took for
• earthquake to take place on
• fault rupture entire length

Northern Sumatra Above the fault
Felt shaking Several minutes
USGS
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Unbelievable !! Earthquake 23,000 Hiroshima Bom
bs
Released Energy by South Asian Earthquake
Es 20X1017 Joules
475 megatons of TNT
USGS
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Effect of the Earthquake on the Length of Day

-2.676 microseconds Too small to be observed !
USGS
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• Earthquake 26 Dec 2004
• Max. displacement on the rupture
• surface between plates 20 m
• Max. displacement of sea bottom
• above the quake source 10 m

USGS
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Rupture a patch along fault's surface by
earthquakes
Larger the rupture patch, Larger the magnitude of
earthquake
as BIG as California !! Patch of fault by Sumatra
-Andaman Islands Earthquake
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• How we can estimate the initial size of the
  rupture by an earthquake?
  
• By studying
• Length of the aftershock zone
• Dimensions of historical earthquakes
• Generated elastic waves

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• Aftershocks
• As 29 Dec 68 aftershock
• M 7.1 The largest, 3h after the main shock
• M 6.0 13 aftershocks

• The Earthquake Ruptures Length Width
• Length 1200-1300 km
• Width 100 km

USGS
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• NO tsunamis by the aftershocks in south Asia
• Number of aftershocks will decrease with time
• Number of aftershocks can be quite variable.

Seismologists are not able to predict
timing and sizes of individual
aftershocks !
USGS
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• Earthquake 26 Dec 2004
• Location Beneath the Indian Ocean west
• of Sumatra, Indonesia
• Epicenter East of the Sunda Trench
• Overriding plate Burma Plate
• Subducting plate India Plate

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What is a Megathrust Earthquake?
What is the Thrust-Faulting? 26 Dec 2004 Re
sult of Thrust - Faulting
Megathrust earthquakes occur where
one tectonic plate subducts
beneath another.
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• Importance of Megathrust Earthquakes
• World's largest recorded earthquakes have all
• been megathrust events
• Often generate large tsunamis that cause
• damage over a much wider area than is
  directly
  
• affected by ground shaking near the
• earthquake's rupture

NEIC
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The megathrust earthquake of Dec 26,
2004, occurred on the interface of India and
Burma plates and was caused by the release of
stresses that develop as the India plate subducts
beneath the overriding Burma plate.
NEIC
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• History of Megathrust Earthquakes
• 1960 Chile, M 9.5
• 1964 Prince William Sound, Alaska, M 9.2
• 1957 Andreanof Islands, Alaska, M 9.1
• 1952 Kamchatka, M 9.0

NEIC
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What is a Tsunami?

• soo-NAH-mee or Harbor Wave
• is a Japanese word tsu means
• harbor nami means wave

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History of Significant Tsunamis in the Region
1797 300 fatalities at Padang, M 8.4 EQ
1833 Numerous victims at W Sumatra, M 8.7 EQ
1843 Many fatalities at the coast of Nias
Island 1861 1000s fatalities at W coast of Sum
atra, M 8.5 EQ 1881 Indias eastern coast, M 7
.9 EQ 883 36,000 fatalities on islands of J
ava Sumatra, Krakatau explosion
1941 M 7.7 Adaman Islands EQ ( Anecdotal
evidence of existing a tsunami)
USGS
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NASA
How the earthquake 26 Dec 2004
generated tsunami?
Imagine a fist rising up from under the water.
Water rolls down off the sides of the fist.
When the bottom of the ocean was deformed by this
megathrust quake, the upward force acted like
that fist, creating massive waves of tsunamis,
which spread out in all directions.
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• Tsunami 2 Wavefronts
• Distance 500 - 850 km
• Height 50 cm

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Tsunami Waves Height Travel time

• Height
• 10 m Coastline of
• Sumatra, near the
• fault boundary
• 4 m Sri Lanka,
• Thailand, Somalia
• Seychelles
• Travel times
• From minutes (Sumatra)
• to 8 hours (Somalia)

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• Tsunami Distance Damage
• Distance alone NO guarantee of safety
• Somalia was hit harder than Bangladesh
• despite being much farther away.

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NASA

• Andaman Islands
• One of the first affected
• places, Dec 26
• 850 km N of epicenter
• As 3 Jan 6000 death

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The Most Affected Area by the Tsunami
NW coast of Sumatra, Aceh province,
Indonesia

• 100 km (62 miles)
• from the epicenter
• Waves height
• 15 m. (50 ft.)
• 80,000 death
• (1/2 of total)

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• Tsunami Sri Lanka India
• Waves travel time 4h
• Devastation the island of Sri Lanka off the
• southeastern tip of India
• Moving the waves westward toward
• southeastern India, along a stretch of
  coastline,
  
• Coromandel Coast
• Destruction of cities, towns, and fishing
  villages
  
• up and down the coast of state of Tamil Nadu

NASA
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• Tsunami Thailand
• Beaches of Khao Lak struck 2-3 h after
• the earthquake
• Location 500 km from the epicenter
• Waves height 10 m. (33 ft.)

NASA
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Tsunami Maldives Male, the capital island of Ma
ldives was severely hit.
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NO Tsunami Warning Issued on 26 Dec 2004 Disaster
!!
NO Tsunami Warning System exists for the Indian
Ocean !!
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Knowledge is Safety! Girl's sea warning saved a h
undred fellow tourists at Phuket beach from
tsunami because of a geography lesson about the
giant waves!!
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The impacts of earthquake tsunami on
South Asia

• Dead139.290
• Injured32,327
• Missed14,950
• Displaced 1,754,433

WHO
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We wish to express our warm thanks to GDHNet
faculties and all groups that contributed their
valuable materials.