Earthquake Engineering
Research Institute
The Great Sumatra Earthquake and
Indian Ocean Tsunami
of December 26, 2004
An illustrated description of their causes and effects
Preface
This presentation was developed to explain the origins of the
Sumatra earthquake of December 26, 2004 and the ensuing
tsunami, and to document the damages caused by the
earthquake and tsunami in so many countries around the
Indian Ocean.

The presentation was created
largely by Widianto, a doctoral
candidate in civil engineering
and president of the EERI
student chapter at the
University of Texas at Austin.

Other contributors include
Sarah Nathe, Craig Comartin,
and Heidi Faison.
This project was supported by funds from the National Science Foundation through
EERI’s Learning From Earthquakes Program under grant # CMS-0131895
“The 26th December 2004 Sumatra-Andaman
earthquake is the fourth largest earthquake in the
world since 1900 and is the largest since the 1964
Prince William Sound, Alaska earthquake.”
United States Geological Survey (USGS)
“The tsunami that struck Southeast Asia on December
26, 2004 has been confirmed as the most devastating
in modern history.”
Guinness Book of World Records
Contents
 Introduction: Plate tectonics, earthquakes
 Sumatra Earthquake
- Tectonic activity
- Observations
- Damage
 Indian Ocean Tsunami
- Basic mechanism
- Videos: before and after giant wave arrival
- Damage
 Tsunamis in the USA
 Tsunami Risk Reduction
 The Earthquake Engineering Research Institute
Introduction – Plate Tectonics
 The Earth is characterized by a small number of lithospheric plates that
float on a viscous underlayer called the asthenosphere.
 Geological evidence shows that plates undergo constant, gradual
change. Magma is continually upwelling at the mid-oceanic ridges and rises
as the seafloor spreads apart.
 In some areas, large sections of plates are forced to move beneath other
plates (surface layers of rocks are absorbed into the earth’s interior). These
areas are called subduction zones.
 A plate being subducted beneath another
Introduction – Plate Tectonics
Source: Earthquakes by Bruce A. Bolt
Introduction – Plate Tectonics
95% of earthquakes occur along the edges of the interacting plates
Source: Earthquakes by Bruce A. Bolt
World’s Largest Magnitude Earthquakes
Earthquake
Magnitude
Year
Approx. casualties
1. Chile
9.5
1960
>2000
2. Prince William
Sound, Alaska
9.2
1964
 125
3. Andreanof
Islands, Alaska
9.1
1957
Not reported
4. Kamchatka
Peninsula
9.0
1952
Not reported
5. Sumatra
9.0
2004
>283,100
(>173,000 in Indonesia)
Source: United States Geological Survey (USGS)
Earthquake Energy
Sumatra-Andaman (2004)
Source: Earthquakes by Bruce A. Bolt
Sumatra Earthquake
Magnitude: 9.0
Date-time: Sunday, December 26,
2004 at 7:58:53 AM (local time)
Depth: 30 km (18.6 miles)
Distances:
* 250 km (155 miles) SSE of Aceh,
Sumatra, Indonesia
* 310 km (195 miles) W of Medan,
Sumatra, Indonesia
* 1260 km (780 miles) SSW of
Bangkok, Thailand
* 1605 km (990 miles) NW of
Jakarta, Java, Indonesia
Source: United States Geological Survey (USGS)
Tectonic Summary
 It occurred on the interface of
the India and Burma plates: an
interplate earthquake.
 India plate subducts beneath
the overriding Burma plate at
the Sunda Trench.
 In the region of the earthquake,
the India plate moves toward the
northeast at a rate of about
6 cm/year relative to the Burma
plate.
 Thrust faulting caused the
earthquake (slip directed
perpendicular to the trench).
 Fault rupture propagated to
the northwest from the epicenter
with a width  100 km and an
average displacement on the fault
plane  20 meters.
6 cm/yr
Source: United States Geological Survey (USGS)
Felt Shaking Reports
Modified Mercalli Intensity Scale:
 Banda Aceh, Sumatra: IX
 Medan, Sumatra: IV
 Port Blair, Andaman Islands: VII
 Subsidence and landslides
were observed in Sumatra.
 A mud volcano near Baratang,
Andaman Islands began erupting
on December 28, 2004.
 Intensity vs. Distance from
Epicenter Plot :
Source: United States Geological Survey (USGS)
Aftershock
Zone
 Extends from
Northern Sumatra to
the Andaman Islands,
~ 1300 km to the north.
 Largest aftershock
directly following the
main shock was M =
7.1 in the Nicobar
Islands.
On March 28, 2005, a
M = 8.7 earthquake
occurred in a region of
the fault southeast of
the Dec 26th mainshock
and its rupture zone.
Epicenter of mainshock,
28 Mar 2005
Earthquake Damage
Location: Banda Aceh,
Sumatra, Indonesia
Banda Aceh
epicenter
Photo: Jose Borrero
Structural damage to concrete frame building.
Earthquake Damage
Location: Banda Aceh,
Sumatra, Indonesia
Banda Aceh
epicenter
Photo: Murat Saatcioglu, Ahmed
Ghobarah, Ioan Nistor
Partial collapse of concrete frame building due to column failure.
Earthquake Damage
Location: Banda Aceh,
Sumatra, Indonesia
Banda Aceh
epicenter
Photos: Murat Saatcioglu, Ahmed
Ghobarah, Ioan Nistor
Partial collapse of concrete frame building due inadequate column reinforcement.
Earthquake Damage
Location: Banda Aceh,
Sumatra, Indonesia
Banda Aceh
epicenter
Photo: Jose Borrero
Architectural damage to the
Grand Mosque tower.
Earthquake Damage
Location: Port Blair,
Andaman Islands
Port Blair
epicenter
Column of residential building damaged by ground motion.
Source: Geological Survey of India
Earthquake Damage
Longitudinal (50 m long)
crack on Kamraj Road after
the earthquake
Location: Port Blair,
Andaman Islands
Port Blair
epicenter
Major crack showing a rupture width of
15 cm on Kamraj Road after the
earthquake
Source: Geological Survey of India
Earthquake and Tsunami
Not all earthquakes generate tsunamis.
An earthquake must have certain characteristics in order to
generate a tsunami:
1. Epicenter is underneath or near the ocean.
2. Fault causes vertical movement of the sea floor (up to
several meters) over a large area (up to 100,000 km2).
3. Large magnitude ( > 7.5 ) AND shallow focus ( < 70 km).
Source: Earthquakes by Bruce A. Bolt
Basic Tsunami Mechanism
 An earthquake causes a
vertical movement of the
seafloor, which displaces the
sea water.
 Large waves then
radiate from the epicenter
in all directions.
Tsunami Explained
 A tsunami is series of traveling ocean waves of extremely long length
generated primarily by earthquakes occurring below or near the ocean floor.
 Tsunami waves propagate across the deep ocean with a speed exceeding
800 km/h ( 500 mph) and a wave height of only a few tens of centimeters or
less.
 As they reach the shallow waters of the coast, the waves slow down and
their height increases up to tens of meters (30 ft) or more.
Source: NOAA
Tsunami Translated
Japanese word:
“Tsu“ means
“harbor”
“Nami“ means
“wave”
English translation:
“Harbor wave”
 “Tidal wave” is a misnomer because the cause
is unrelated to tides.
 “Seismic sea wave” is misleading because a
tsunami can be caused by non-seismic events,
and it is not dangerous in the open ocean.
Water Recession: A Precursor
Wave Generation
Draw Down Effect
From: Nature Publishing Group
From: Nature Publishing Group
Kalutara Beach, Sri Lanka
From: Digital Globe
Tsunami Wave Appearance
Source: www.waveofdestruction.org

A tsunami wave crest has
three general appearances
from shore:




Fast-rising tide
Cresting wave
A step-like change in the
water level that advances
rapidly (called a bore)
Series of waves



A bore on the Qian Tang Jiang River, China
Most tsunamis come in a series of waves that may last for several
hours
The outflow of water back to the sea between waves can cause
more damage than the original incoming wave fronts
The first wave is rarely the largest
Tsunami Propagation
National Institute of Advanced Industrial Science and Technology, Japan
Tsunami Damage
Location: Lhoknga, Indonesia
Lhoknga
Before Tsunami
January 10, 2003
epicenter
After Tsunami
December 29, 2004
Source: National University of Singapore
Tsunami Damage
Location: Lhoknga, Indonesia
Lhoknga
Photo: Jose Borrero
Exposed
bridge piers of
road that
washed away. epicenter
High Water Mark
Overturned
ship
Broken Trees
Photo: Jose Borrero
Damage zone showing an
overturned tanker, trees
snapped in half, and the
high water mark on islands
where vegetation was
stripped away.
Tsunami Damage
Location: Gleebruk, Indonesia
Gleebruk
Before Tsunami
April 12, 2004
epicenter
After Tsunami
January 2, 2005
Source: Digital Globe
Tsunami Damage
Gleebruk
epicenter
Before Tsunami
April 12, 2004
After Tsunami
January 2, 2005
Source: Digital Globe
Tsunami Damage
Location: Banda Aceh, Indonesia
Banda Aceh
Before Tsunami
June 23, 2004
epicenter
After Tsunami
December 28, 2004
Source: Digital Globe
Tsunami Damage
Location: Banda Aceh, Indonesia
Photo: Jose Borrero
A boat was
lifted on top
of houses
by the
waves.
Banda Aceh
epicenter
Damage was caused by
both water and water-borne
debris.
Photo: Jose Borrero
Tsunami Damage
Location: Banda Aceh & Lhoknga,
Indonesia
Banda Aceh
epicenter
The tsunami waves came
from many directions and
flowed across the tip of
northeastern Sumatra.
Graphic: Jose Borrero
Tsunami Damage
Location: Thailand
Kerala
Coast
Thailand
Damage to Kao
Lak Resort from
tsunami waves.
epicenter
Photo: Curt Edwards
Despite the presence of debris,
this naval base building had
little structural damage due to a
retaining wall at its frontage.
Photo: Chitr Lilavivat
Tsunami Damage
Location: Sri Lanka
Flow depths were
about 4.5 m at Yala
Safari Resort, where
water levels were
determined by debris
in the trees (see door
impaled on branch).
Damage to house in Tangala.
Kerala
Coast
Sri Lanka
epicenter
Tsunami Damage
Location: Kerala, India
Kerala Coast
The collapsed front
portion of a concrete
house.
epicenter
In the village of Alappad, the foundations and
the soil beneath many of the houses were
scoured out.
Source: Geological Survey of India
Tsunamis in the U.S.A.



The west coast, from California to Alaska, is vulnerable to
tsunamis from nearby or distant earthquakes.
Hawaii is extremely vulnerable to all tsunamis in the Pacific
Ocean.
California, Oregon, Washington, Alaska and Hawaii all have
tsunami education programs for residents and visitors,
coastal signage, and warning response plans.
Photo: Kirkpatrick, NISEE Collection
Tsunami induced damage in Seward, Alaska
from 1964 Alaska earthquake
Photo: Eugene Schader, NISEE Collection
Warped pier in Crescent City, CA caused by
1964 Alaska earthquake tsunami
Historical Tsunamis in the U.S.A.
Tsunami Source
Year
Affected States
Tsunami Casualties
Cascadia Fault
Earthquake
1700
West coast
unknown
Aleutian Earthquake
(Mw = 8.3)
1946
AK, HI , WA, OR, CA
159 (Hilo, Hawaii)
165 (total)
Lituya Bay, Alaska
Landslide
1958
AK
2
Chile Earthquake
(Mw = 9.5)
1960
CA, HI
61 (Hilo, Hawaii)
Alaska Earthquake
(Mw = 9.3)
1964
AK, HI , WA, CA
120 (total)
Sources: NOVA; International Tsunami Information Center (ITIC)
Tsunami Risk Reduction
1. Determine & understand community tsunami risk

Hazard:



Vulnerability:


Study the shape of the sea floor and the coastal topography
Run simulations of tsunamis
Develop maps of potential risk areas
Exposure:

Costal communities, especially with tsunami history
2. Avoid new development in tsunami run-up areas
1.
2.
Designate risk areas as open-space, i.e., parks and agriculture
Zone to minimize human risk
1.
Low density residential zoning
2.
Large single-residence lots
Tsunami Risk Reduction
3. Locate and configure new development in the run-up
areas to minimize future tsunami losses

Avoid inundation areas
i.e. build on high ground
SLOWING

Slowing water currents
i.e. Conserve or replant coastal belts
of forest and mangrove swamps
STEERING

Steering water forces
i.e. angled, by-pass walls

Blocking water forces
i.e. Build sea walls
BLOCKING
Source: National Tsunami Hazard Mitigation Program (NTHMP)
Tsunami Risk Reduction
4. Design and construct new buildings to minimize
tsunami damage

Heavy and rigid structure

Raise building on stilts*

Many openings on the
ground floor *

Orient perpendicular to the
shoreline:
*Use caution with this design in areas
with high earthquake-shaking risk.
Elevated restaurant in Hilo, Hawaii. Lower level is designed
to allow waves to pass through.
Source: National Tsunami Hazard Mitigation Program
Tsunami Risk Reduction
4. Tsunami-resistant buildings (cont.)
Overturning
Tsunami forces on
structures
Sliding
WAVE
Water pressure
& debris impact
Scouring
Rigid connection
Buoyancy
Lowest
horizontal
structure
above wavecrest
Structure designed to resist
tsunami forces
Horizontal
member
perpendicular to
the wave
Lateral bracing
Deep protected piles
Source: National Tsunami Hazard Mitigation Program (NTHMP)
Caveat: Remember EarthquakeResistant Design Principles


Most communities at risk from tsunamis are also at risk from
damaging earthquakes
Buildings designed well for earthquakes typically perform
well in tsunamis
Photo: Jose Borrero
Well-designed building standing amidst the
rubble in Banda Aceh, Indonesia
Photo: Jose Borrero
Well-designed building withstood tsunami forces
without collapse in Banda Aceh, Indonesia
Tsunami Risk Reduction
5. Protect existing development through
redevelopment, retrofit, and land reuse plans and
projects
6. Take special precautions in locating and designing
infrastructure and critical facilities



Locate critical infrastructure (water plants, hospitals, etc)
outside the tsunami danger zone
Relocate or protect critical infrastructure
Plan for emergency and recovery
Tsunami Risk Reduction

Plan for Evacuation




Identify vertical evacuation buildings
Create horizontal evacuation routes
Develop early warning systems
Educate and inform public
Tsunami Risk Reduction
Tsunami early warning system:



Pressure sensors sit on the ocean
bottom and measure the weight of
water column above them.
If a tsunami passes overhead, the
pressure increases and the sensor
sends a signal to a buoy sitting on the
sea surface.
The buoy then sends a signal to a
satellite, which in turn alerts a staffed
early warning center.
Tsunami Risk Reduction
The least expensive and the most important mitigation effort is …
"Even without a warning system, even in places where they
didn't feel the earthquake, if people had simply
understood that when you see the water go down, when
you hear a rumble from the coast, you don't go down to
investigate, you grab your babies and run for your life,
many lives would have been saved."
Lori Dengler, Humboldt State University
New Scientist Magazine
January 15, 2005
The power of knowledge:



Victor Desosa saved the
village of Galbokka in Sri
Lanka because he knew
what to do when the water
receded.
Only one inhabitant in his
village was killed.
Casualty rates in nearby
villages were 70 – 90 %
“Natural hazards are inevitable.
Natural disasters are not.”
John Filson, USGS retired
New York Times
December 27, 2004
Earthquake Engineering
Research Institute

EERI is a professional, association dedicated to
reducing earthquake risk.

Members of EERI work in the many different
fields of research and professional practice
dedicated to reducing earthquake losses.
EERI Programs

Publications – Website, Monthly Newsletter and
Quarterly Technical Journal--Earthquake Spectra





Technical Seminars & National Conferences
Web based World Housing Encyclopedia
5 Regional Chapters -- Political Advocacy
20 Student Chapters
Learning From Earthquakes Program
Field reconnaissance of earthquake impacts to learn
lessons for research and practice
To contact us or become a member of EERI, visit our website:
www.eeri.org
References
 United States Geological Survey (USGS)
 U.S. National Oceanic and Atmospheric Administration (NOAA)
 UNESCO / Intergovernmental Oceanographic Commission (IOC)
 International Tsunami Information Center (ITIC)
 Laboratoire de Geophysique, France (LDG)
 Earthquakes: A Primer, Bruce A . Bolt, W.H. Freeman, 1978
 Digital Globe
 Geological Survey of India
 National University of Singapore
 New Scientist magazine, Issue #2482, January 15, 2005
 BBC News
 Nature, Vol. 433, January 27, 2005, Nature Publishing Group
 Sri Lanka Reconnaissance Teams:
http://walrus.wr.usgs.gov/tsunami/srilanka05/ &
http://www.gtsav.gatech.edu/cee/groups/tsunami/index.html
References (cont.)
 Natural Tsunami Hazard Mitigation Program (NTHMP), Designing for
Tsunamis, March 2001
 National Information Service for Earthquake Engineering (NISEE),
Earthquake Image Database, Karl Steinbrugge Collection
 www.wavesofdestruction.org
 “Field Survey of Northern Sumatra,” Jose Borrero, EERI Newsletter,
March 2005
 Pacific Tsunami Museum
 NOVA: “The Wave that Shook the World,” PBS
http://www.pbs.org/wgbh/nova/tsunami/
 Metro TV, Surabaya Citra Televisi Indonesia (SCTV), Rajawali Citra
Televisi Indonesia (RCTI)
 Prof. Wiratman Wangsadinata, Wiratman & Associates Consulting
Company, Indonesia
 EERI’s Virtual Clearinghouse:
http://www.eeri.org/lfe/clearinghouse/sumatra_tsunami/overview.html