2004 Indian Ocean earthquake was an undersea megathrust earthquake
that occurred at 00:58:53 UTC on December 26, 2004, with an
epicentre off the west coast of Sumatra, Indonesia.
The quake itself is known by the scientific community
. The resulting tsunami
itself is given various names, including the
2004 Indian Ocean tsunami
, Indonesian Tsunami
earthquake was caused by subduction and
triggered a series of devastating tsunami
along the coasts of most landmasses bordering the Indian Ocean, killing nearly 230,000 people in eleven countries,
and inundating coastal communities with waves up to high.
was one of the
deadliest natural disasters in recorded history
. Indonesia, Sri
Lanka, India, and
Thailand were the
With a magnitude
9.1 and 9.3, it is the second
earthquake ever recorded on a seismograph
. This earthquake had the longest
duration of faulting ever observed, between 8.3 and 10 minutes.
the entire planet to vibrate as much as 1 cm (0.4 inches)
and triggered other earthquakes as far away as Alaska.
The plight of the many affected
people and countries
prompted a widespread humanitarian
. In all, the worldwide community donated more than $7
billion (2004 U.S. dollars
was initially reported as
February 2005 scientists revised the estimate of the magnitude to
9.3. Although the Pacific
Tsunami Warning Center
has accepted these new numbers, the
United States Geological
has so far not changed its estimate of 9.1. The most
recent studies in 2006 have obtained a magnitude of Mw
9.1 to 9.3. Dr. Hiroo
Kanamori of the California Institute of
Technology believes that Mw = 9.2 is a good
representative value for the size of this great
hypocentre of the main earthquake was
approximately 160 km (100 mi), in the Indian Ocean just
north of Simeulue island, off
the western coast of northern Sumatra, at a depth of 30 km
(19 mi) below mean sea level
(initially reported as 10 km).
The northern section of
the Sunda megathrust
, which had
been assumed dormant
, ruptured; the rupture
having a length of 1600 km. The size of the rupture caused plate
shifting of up to 20 m, causing the earthquake (followed by the
tsunami) to be felt simultaneously as far away as Bangladesh, India, Malaysia, Myanmar, Thailand, Singapore and the Maldives.
Splay faults or secondary "pop up faults" caused long narrow parts of the sea floor to pop up in seconds elevating the height and increased the speed of waves to cause the complete destruction of the nearby Indonesian town of Lhoknga.
lies between the Pacific Ring of
Fire along the north-eastern islands adjacent to and including
Guinea and the Alpide belt
along the south and west from Sumatra, Java, Bali, Flores, and
Great earthquakes such as the Sumatra-Andaman event, which are
invariably associated with megathrust
events in subduction zones
that can account for
a significant fraction of the global earthquake moment across
century-scale time periods. The Sumatra-Andaman earthquake was the
largest earthquake since 1964, and the second largest since the
October 16, 1737.
Graphic of largest earthquakes
Of all the seismic moment
earthquakes in the 100 years from 1906 through 2005, roughly
one-eighth was due to the Sumatra-Andaman event. This quake, together
with the Good Friday
Earthquake (Alaska, 1964) and
Chilean Earthquake (1960), account for almost half of the total
The much smaller but still catastrophic 1906 San Francisco earthquake
is included in the diagram at right for perspective. Mw
denotes the magnitude of an earthquake on the moment magnitude scale
1900 the only earthquakes recorded with a greater magnitude were
the 1960 Great
Chilean Earthquake (magnitude 9.5) and the 1964 Good Friday Earthquake in Prince
William Sound (9.2). The only other recorded earthquake of
magnitude 9.0 or greater was off Kamchatka, Russia, on November
4, 1952 (magnitude 9.0).
Each of these megathrust earthquakes
tsunamis in the Pacific Ocean, but the death toll from these was
significantly lower. The worst of these caused only a few thousand
deaths, primarily because of the lower population density
along the coasts near
affected areas and the much greater distances to more populated
very large megathrust
earthquakes occurred in 1868 (Peru, Nazca Plate and South American Plate); 1827 (Colombia, Nazca Plate and South American Plate); 1812
(Venezuela, Caribbean Plate and
South American Plate) and 1700 (Cascadia Earthquake, western U.S. and
Canada, Juan de Fuca Plate and North American Plate).
all believed to have been of greater than magnitude 9, but no
accurate measurements were available at the time.
The megathrust earthquake
unusually large in geographical
extent. An estimated
1,600 km (994 mi) of fault
slipped (or ruptured) about 15 m (50 ft) along the
where the India Plate
slides (or subducts) under the
overriding Burma Plate
. The slip did not
happen instantaneously but took place in two phases over a period
of several minutes:
India Plate is part of the great
Indo-Australian Plate, which
underlies the Indian
Ocean and Bay of
Bengal, and is drifting north-east at an average of
6 cm/year (2 inches per year). The India Plate meets
the Burma Plate (which is considered a
portion of the great Eurasian Plate)
at the Sunda
Trench. At this point the India Plate subducts
beneath the Burma Plate, which carries the Nicobar
Islands, the Andaman Islands, and northern Sumatra.
- Seismographic and acoustic data indicate that the first phase
involved a rupture about 400 km (250 mi) long and
100 km (60 mi) wide, located 30 km (19 mi)
beneath the sea bed—the largest rupture ever known to have been
caused by an earthquake. The rupture proceeded at a speed of about
2.8 km/s (1.7 mi/s) or
10,000 km/h (6,300 mph), beginning off the coast of
Aceh and proceeding north-westerly over a period of
about 100 seconds.
pause of about another 100 seconds took place before the rupture
continued northwards towards the Andaman and Nicobar Islands. However, the northern rupture occurred more
slowly than in the south, at about 2.1 km/s (1.3 mi/s) or 7,600 km/h (4,700 mph),
continuing north for another five minutes to a plate boundary where
the fault type changes from subduction to strike-slip (the two
plates slide past one another in opposite directions). This reduced
the speed of the water displacement and so reducing the size of the
tsunami that hit the northern part of the Indian Ocean.
India Plate sinks deeper and deeper beneath the Burma Plate until
the increasing temperature and pressure drive volatiles
out of the subducting plate. These
volatiles rise into the overlying plate causing partial melting
and the formation of
. The rising magma intrudes into the
crust above and exits the Earth's crust through volcanoes
in the form of a volcanic arc
. The volcanic activity that
results as the Indo-Australian Plate subducts the Eurasian Plate
has created the Sunda Arc
As well as the sideways movement between the plates, the sea floor
is estimated to have risen by several
metres, displacing an estimated 30 km3
(7 cu mi) of
water and triggering devastating tsunami
waves. The waves did not originate from a point source
, as was inaccurately depicted in
some illustrations of their paths of travel, but rather radiated
outwards along the entire 1,600 km (994 mi) length of the
rupture (acting as a line source
greatly increased the geographical area over which the waves were
observed, reaching as far as Mexico, Chile, and the
Arctic. The raising of the
sea floor significantly reduced the capacity of the Indian Ocean, producing a permanent rise in the global sea level by an estimated 0.1 mm
(0.01 cm or 0.0001 m).
Aftershocks and other earthquakes
aftershocks were reported off the
Islands, the Nicobar Islands and the region of the original epicentre in the
hours and days that followed. The largest
aftershock, which originated off the coast of the Sumatran
island of Nias, registered
a magnitude of 8.7, prompting debate among seismologists as to
whether it should be classified as an aftershock of the December
2004 quake or as a "triggered earthquake" (which typically differs
from an aftershock in that it is not located along the same fault
line and may be as large or larger than the earthquake which
This earthquake was so large that it produced
its own aftershocks (some registering a magnitude of as great as
6.1) and presently ranks as the 7th largest earthquake on record
since 1900. Other aftershocks of up to magnitude 6.6 continued to
shake the region daily for up to three or four months. As well as
continuing aftershocks, the energy released by the original
earthquake continued to make its presence felt well after the
event. A week after the earthquake, its reverberations could still
be measured, providing valuable scientific data about the Earth's
Indian Ocean earthquake came just three days after a magnitude 8.1
earthquake in an uninhabited region west of New Zealand's sub-Antarctic Auckland
Islands, and north of Australia's Macquarie
This is unusual, since earthquakes of
magnitude 8 or more occur only about once per year on average. Some
seismologists have speculated about a connection between these two
earthquakes, saying that the former one might have been a catalyst
to the Indian Ocean earthquake, as the two earthquakes happened on
opposite sides of the Indo-Australian Plate
. However, the
U.S. Geological Survey
evidence of a causal relationship in this incident. Coincidentally, the
earthquake struck almost exactly one year (to the hour) after a 6.6
magnitude earthquake killed an estimated 30,000 people in the city
of Bam in Iran on December
scientists confirm that the December earthquake had activated
Mountain, a volcano
in Aceh province along the same range of peaks as Mount Talang, while the 2005 Sumatran earthquake had sparked activity in Lake Toba, an ancient crater in Sumatra. Geologists say that
the eruption of Mount
Talang in April 2005 is connected to the December
Energy released by the earthquake
The energy released on the Earth's surface only
which is the seismic potential for
, by the 2004 Indian Ocean earthquake and tsunami was
estimated at 1.1×1017 joules
26.3 megatons of TNT. This energy is equivalent to over 1502 times
that of the Hiroshima atomic bomb, but
less than that of Tsar
Bomba, the largest nuclear weapon ever detonated.
However, this is but a tiny fraction of the total work
energy) by this quake, 4.0×1029 ergs
), the vast majority underground.
This equates to 4.0×1022
J, over 363,000 times more than
. This is a truly enormous figure,
equivalent to 9,560 gigatons of TNT
(550 million times that of Hiroshima), or about 370
years of energy use in
the United States
at 2005 levels of 1.08×1020
The only recorded earthquakes with a larger MW
were the 1960 Chilean and 1964 Alaskan quakes, with
joules (250 ZJ) and 7.5×1022
(75 ZJ) respectively.
The earthquake generated a seismic oscillation of the Earth's
surface of up to 20–30 cm (8–12 in), equivalent to the
effect of the tidal forces
caused by the Sun
and Moon. The shock waves of the earthquake were felt
across the planet; as far away as the U.S. state of Oklahoma, where vertical movements of 3 mm
(0.12 in) were recorded.
By February 2005, the
earthquake's effects were still detectable as a 0.02 mm
complex harmonic oscillation of the Earth's surface, which
gradually diminished and merged with the incessant free oscillation
of the Earth more than 4 months after the earthquake.
Because of its enormous energy release and shallow rupture depth,
the earthquake generated remarkable seismic ground motions around
the globe, particularly due to huge Rayleigh elastic waves
that exceeded 1 cm
in vertical amplitude everywhere on Earth. The record section plot
below displays vertical displacements of the Earth's surface
recorded by seismometers from the IRIS/USGS Global Seismographic
Network plotted with respect to time (since the earthquake
initiation) on the horizontal axis, and vertical displacements of
the Earth on the vertical axis (note the 1 cm scale bar at the
bottom for scale). The seismograms are arranged vertically by
distance from the epicenter in degrees. The earliest, lower
amplitude, signal is that of the compressional (P) wave, which
takes about 22 minutes to reach the other side of the planet (the
antipode; in this case near Ecuador). The largest amplitude signals
are seismic surface waves that reach the antipode after about 100
minutes. The surface waves can be clearly seen to reinforce near
the antipode (with the closest seismic stations in Ecuador), and to
subsequently encircle the planet to return to the epicentral region
after about 200 minutes. A major aftershock (magnitude 7.1) can be
seen at the closest stations starting just after the 200 minute
mark. This aftershock would be considered a major earthquake under
ordinary circumstances, but is dwarfed by the mainshock.
Vertical-component ground motions
recorded by the IRIS/USGS Global Seismographic Network
The shift of mass and the massive release of energy very slightly
altered the Earth's rotation. The exact amount is not yet known,
but theoretical models suggest the earthquake shortened the length
of a day by 2.68 microseconds
, due to a
decrease in the oblateness
of the Earth. It
also caused the Earth to minutely "wobble" on its axis by up to
2.5 cm (1 in) in the direction of 145° east longitude
, or perhaps by up to 5 or 6 cm (2.0
to 2.4 in). However, because of tidal effects of the Moon
, the length of a day increases at an average of 15
per year, so any rotational change
due to the earthquake will be lost quickly. Similarly, the natural
of the Earth, which
in some cases can be up to 15 m (50 ft), will eventually
offset the minor wobble produced by the earthquake.
More spectacularly, there was 10 m (33 ft) movement laterally
and 4–5 m (13–16 ft) vertically along the fault line. Early
speculation was that some of the smaller islands south-west of
Sumatra, which is on the Burma Plate
(the southern regions are on the Sunda
), might have moved south-west by up to 36 m
(118 ft), but more accurate data released more than a month
after the earthquake found the movement to be about 20 cm
(7.9 in). Since movement was vertical as well as lateral, some
coastal areas may have been moved to below sea level. The Andaman and
Nicobar Islands appear to have shifted south-west by around 1.25 m
(4.1 ft) and to have sunk by 1 m (3.28 ft).
In February 2005, the Royal Navy
seabed around the earthquake zone, which varies in depth between
1,000 m and 5,000 m (3,300 ft and 16,500 ft). The survey,
conducted using a high-resolution, multi-beam sonar
system, revealed that the earthquake had made a
huge impact on the topography of the seabed. 1,500-meter
(5,000 ft) high thrust ridges created by previous geologic
activity along the fault had collapsed, generating landslides
several kilometers wide. One such
landslide consisted of a single block of rock some 100 m high and
2 km long (300 ft by 1.25 mi). The momentum of the
water displaced by tectonic uplift had also dragged massive slabs
of rock, each weighing millions of tons, as far as 10 km
(7 mi) across the seabed. An oceanic
several kilometres wide was exposed in the earthquake
and Jason 1
satellites happened to pass over the tsunami
as it was crossing the ocean. These satellites carry radars
that measure precisely the height of the water
surface; anomalies of the order of 50 cm (20 in) were
measured. Measurements from these satellites may prove invaluable
for the understanding of the earthquake and tsunami. Unlike data
from tide gauges
installed on shores,
measurements obtained in the middle of the ocean can be used for
computing the parameters of the source earthquake without having to
compensate for the complex ways in which close proximity to the
coast changes the size and shape of a wave.
Animation of the tsunami caused by the earthquake showing how the
tsunami radiated from the entire length of the rupture.
Scale showing the size of the tsunami waves that hit Indonesia on
26 December 2004
The sudden vertical rise of the seabed
several metres during the earthquake displaced massive volumes of
water, resulting in a tsunami
the coasts of the Indian Ocean. A tsunami which causes damage far
away from its source is sometimes called a teletsunami
and is much more likely to be
produced by vertical motion of the seabed than by horizontal
The tsunami, like all others, behaved very differently in deep
water than in shallow water. In deep ocean water, tsunami waves
form only a small hump, barely noticeable and harmless, which
generally travels at a very high speed of 500 to 1,000 km/h
(310 to 620 mph); in shallow water near coastlines, a tsunami
slows down to only tens of kilometres an hour but in doing so forms
large destructive waves. Scientists investigating the damage in
Aceh found evidence that the wave reached a height of 24 m
when coming ashore along large stretches of the coastline, rising
to 30 m (100 ft) in some areas when travelling
satellites recorded the heights of
tsunami waves in deep water: at two hours after the earthquake, the
maximum height was 60 cm (2 ft). These are the first such
observations ever made. Unfortunately these observations could not
be used to provide a warning, since the satellites were not built
for that purpose and the data took hours to analyze.
According to Tad Murty
, vice-president of
the Tsunami Society
, the total
energy of the tsunami waves was equivalent to about five megatons
). This is more than twice the
total explosive energy used during all of World War II
(including the two atomic bombs
), but still a couple of orders of magnitude
less than the energy
released in the earthquake itself. In many places the waves reached
as far as 2 km (1.24 mi) inland.
Because the fault affected by the earthquake was in a nearly
north-south orientation, the greatest strength of the tsunami waves
was in an east-west direction. Bangladesh, which lies at the northern end of the Bay of Bengal, had very few casualties despite being a low-lying
country relatively near the epicenter.
It also benefited
from the fact that the earthquake proceeded more slowly in the
northern rupture zone, greatly reducing the energy of the water
displacements in that region.
Coasts that have a landmass between them and the tsunami's location
of origin are usually safe; however, tsunami waves can sometimes
around such landmasses.
Indian state of Kerala was hit by
the tsunami despite being on the western coast of India, and the
western coast of Sri Lanka also suffered substantial
impacts. Also distance alone was no guarantee of
safety; Somalia was hit harder than Bangladesh despite being much
of the distances involved, the tsunami took anywhere from fifteen
minutes to seven hours (for Somalia) to reach the various coastlines.
northern regions of the Indonesian island of Sumatra were hit very
quickly, while Sri Lanka and the east coast of India were hit
roughly 90 minutes to two hours later. Thailand was also
struck about two hours later despite being closer to the epicentre,
because the tsunami travelled more slowly in the shallow Andaman Sea off its western coast.
tsunami was noticed as far as Struisbaai in South Africa, some
8,500 km (5,300 mi) away, where a 1.5 m (5 ft)
high tide surged on shore about 16 hours after the
It took a relatively long time to reach this
spot at the southernmost point of Africa, probably because of the
broad continental shelf off South Africa and because the tsunami
would have followed the South African coast from east to west.
tsunami also reached Antarctica, where tidal gauges at Japan's Showa Base recorded oscillations of up to a
metre, with disturbances lasting a couple of days.
the tsunami's energy escaped into the Pacific Ocean, where it produced small but measurable tsunamis
along the western coasts of North and South America, typically
around 20 to 40 cm (7.9 to 15.7 in). At Manzanillo, Mexico, a
2.6 m (8.5 ft) crest-to-trough tsunami was
measured. As well, the tsunami was large enough to be
detected in Vancouver, British
puzzled many scientists, as the tsunamis measured in some parts of
South America were larger than those measured in some parts of the
Indian Ocean. It has been theorized that the tsunamis were focused
and directed at long ranges by the mid-ocean ridges
which run along the margins
of the continental plates.
Signs and warnings
Despite a lag of up to several hours between the earthquake and the
impact of the tsunami, nearly all of the victims were taken
completely by surprise. There were no tsunami warning systems
in the Indian
Ocean to detect tsunamis or to warn the general populace living
around the ocean. Tsunami detection is not easy because while a
tsunami is in deep water it has little height and a network of
sensors is needed to detect it. Setting up the communications
infrastructure to issue timely warnings is an even bigger problem,
particularly in a relatively poor part of the world.
Tsunami are much more frequent in the Pacific Ocean because of
earthquakes in the "Ring of
", and an effective tsunami warning system has long been in
place there. Although the extreme western edge of the Ring of Fire
extends into the Indian Ocean (the point where this earthquake
struck), no warning system exists in that ocean. Tsunamis there are
relatively rare despite earthquakes being relatively frequent in
Indonesia. The last major tsunami was caused by the
Krakatoa eruption of 1883.
It should be noted that
not every earthquake produces large tsunamis; on March 28, 2005, a
magnitude 8.7 earthquake hit roughly the same area of the Indian
Ocean but did not result in a major tsunami.
In the aftermath of the disaster, there is now an awareness of the
need for a tsunami warning system for the Indian Ocean. The
started working on an
Indian Ocean Tsunami
and by 2005 had the initial steps in place.
even proposed creating a unified global tsunami warning system, to
include the Atlantic
Ocean and Caribbean.
The first warning sign of a possible tsunami is the earthquake
itself. However, tsunami can strike thousands of kilometres away
where the earthquake is only felt weakly or not at all. Also, in
the minutes preceding a tsunami strike, the sea often recedes
temporarily from the coast. Around the Indian Ocean, this rare
sight reportedly induced people, especially children, to visit the
coast to investigate and collect stranded fish on as much as
2.5 km (1.6 mi) of exposed beach, with fatal results.
However, not all tsunami causes this 'disappearing sea' effect. In
some cases, there are no warning signs at all. The sea will
suddenly swell without retreating surprising many people and giving
them little time to flee.
the few coastal areas to evacuate ahead of the tsunami was on the
Indonesian island of Simeulue, very close to the epicentre.
folklore recounted an earthquake and tsunami in 1907, and the
islanders fled to inland hills after the initial shaking yet before
the tsunami struck. On Maikhao beach in northern Phuket, Thailand, a 10-year-old British tourist named Tilly
Smith had studied tsunami in geography class at school and
recognised the warning signs of the receding ocean and frothing
She and her parents warned others on the beach,
which was evacuated safely. John
, a biology teacher from Scotland, also recognised the
signs at Kamala Bay north of Phuket, taking a busload of
vacationers and locals to safety on higher ground.
Anthropologists had initially expected the
aboriginal population of the Andaman
Islands to be badly affected by the tsunami and even feared
the endangered Onge tribe could have
been wiped out.
Of the six native tribes only the
Nicobarese, who had converted to Christianity and taken up
agriculture in place of their previous hunter-gatherer
lifestyle, and mainland
settlers had suffered significant losses. Onge tribespeople
explained that the sea and land always fought over boundaries.
First the spirits became angry and shook the trees and then when
they saw changes in the sea and clouds they knew “the sea would
enter the jungle and mix with the land until they decided on a new
”. The aboriginal
tribes evacuated and suffered few or no losses.
Tsunami phases and wave form
A tsunami can arrive at a coastline in one of two ways. First,
there's the negative wave where the trough of the wave precedes the
actual arrival of the crest or 'wave' itself. Here, the common and
better known warning sign of an impending tsunami strike is a
rapidly receding sea followed by a sudden onrushing body of water
traveling inland at high speed. The second form in which a tsunami
arrives is the positive wave or crest first. In this case, the
warning signs are much more vague if any. The sea will usually
start rising immediately rather slowly at first without the
receding phase, much more like an on-coming high tide but instead
of stopping at tidal level it will keep on rising faster and faster
until the crest of the tsunami passes and continues moving inland.
Therefore, the second form of tsunami waves are usually more
dangerous owing to the fact that it can arrive without much warning
giving residents less time to prepare and outrun the tsunami. These
two types of tsunamis are usually generated simultaneously(in
opposing direction of travel) by a megathrust earthquake similar to
the 2004 Indian Ocean earthquake.
Retreat-rise cycle (negative wave)
The tsunami was a succession of several waves, occurring in retreat
and rise cycles with a period of over 30 minutes between each peak.
The third wave was the most powerful and reached highest, occurring
about an hour and a half after the first wave. Smaller tsunami
continued to occur for the rest of the day.
Image:2ndTsunamiWave.JPG|Second tsunami wave
starting to retreat, Kata Noi Beach,
Image:KataNoiRecedingWaters.JPG|Receding waters after
the second tsunami, 10:20 a.m.Image:KataNoiHighest.jpg|3rd tsunami
wave, 11:00 a.m.Image:KataNoiMoreWaves.JPG|4th tsunami wave, 11:22
Rise-retreat-rise cycle (positive wave)
If the crest of a tsunami arrives first, there won't be any
recession. The sea level will increase rapidly to inundate
everything in the path of the tsunami. This appears to be the case
in countries such as Sri Lanka and India that lies to the west of
the Andaman-Sumatra fault where the tsunami originates.After the
first tsunami wave passed, water will then begin to flow back into
the ocean receding at a quicker pace as the second wave
Damage and casualties
The U.S. Geological Survey
the toll as 283,100 killed, 14,100 missing, and
1,126,900 people displaced. However, more recent analysis
compiled by the United Nations
a total of 229,866 people lost, including 186,983 dead and 42,883
missing (UN Office of the Envoy for Tsunami Recovery, The Human
) . The figure excludes 400 to 600 people who
are believed to have perished in Myanmar, which is more than that government's official
figure of only 61 dead.
If the higher Myanmar figures are
reliable, the death toll would include at least 230,000 people.
Measured in lives lost, this is one of the ten worst
earthquakes in recorded history
, as well as the single worst
tsunami in history.
The tsunami caused serious damage and deaths as far as the east
coast of Africa
, with the furthest recorded
death due to the tsunami occurring at Rooi
in South Africa
, away from the
epicentre. In total, eight people in South Africa died due to
abnormally high sea levels and waves.
Relief agencies report that one-third of the dead appear to be
children. This is a result of the high proportion of children in
the populations of many of the affected regions and because
children were the least able to resist being overcome by the
surging waters. Oxfam
went on to report that
as many as four times more women than men were killed in some
regions because they were waiting on the beach for the fishermen to
return and looking after their children in the houses.
In addition to the large number of local residents, up to
9,000 foreign tourists (mostly Europeans) enjoying the peak
holiday travel season were among the dead or missing, especially
people from the Nordic countries
European nation hardest hit may have been Sweden, whose
death toll was 543.
States of emergency were declared in
Lanka, Indonesia, and the Maldives.
estimated at the outset that the relief operation
(which is presently still underway) would be the costliest in human
history. UN Secretary-General
has stated that reconstruction
would probably take between five and ten years. Governments and
fear the final death
may double as a result of diseases, prompting a massive
For purposes of establishing timelines of local events, the
of affected areas are: UTC+3:
(Kenya, Madagascar, Somalia, Tanzania); UTC+4: (Mauritius, Réunion,
Seychelles); UTC+5: (Maldives); UTC+5:30: (India); UTC+6:
(Bangladesh, Sri Lanka); UTC+6:30: (Cocos Islands, Myanmar); UTC+7:
(Indonesia (western), Thailand); UTC+8: (Malaysia, Singapore).
Since the earthquake occurred at 00:58:53 UTC
add the above offsets to find the local time of the
|Note: All figures are approximate and
subject to change. The first column links to more details
on specific countries.
Includes those reported under 'Confirmed'. If no
separate estimates are available, the number in this column is the
same as reported under 'Confirmed'.
Does not include approximately 19,000 missing people
initially declared by Tamil Tiger
authorities from regions under their control.
Data includes at least 2,464 foreigners.
Does not include South African citizens who died
outside of South Africa (eg, tourists in Thailand). For more
information on those deaths, see this
earthquake and resulting tsunami affected many countries in
Southeast Asia and beyond, including Indonesia, Sri
Lanka, India, Thailand, the Maldives, Somalia, Myanmar, Malaysia, Seychelles and others.
Countries most affected by the 2004
Indian Ocean earthquake.
Many other countries, especially
and those in Europe
, had large numbers of citizens traveling in
the region on holiday. Both Sweden and
Germany lost over 500 citizens each in the
Event in historical context
earthquake was the biggest in the
Ocean in some 700 years, or since around A.D.
2008, a team of scientists working on Phra Thong, a barrier island
along the hard-hit west coast of Thailand, reported evidence of at least three previous major
tsunamis in the preceding 2,800 years, the most recent from about
550 to 700 years ago. A second team found similar evidence of
previous tsunamis during the last 1,200 years in Aceh, a province
at the northern tip of Sumatra.
Radiocarbon dating of bark fragments in soil below the second sand
layer led the scientists to estimate that the most recent
predecessor to the 2004 tsunami probably occurred between A.D. 1300
was the fourth most
powerful earthquake recorded since 1900, and the confirmed death toll
is just under 200,000 due to the
ensuing tsunami. The deadliest earthquakes since 1900 were
the Tangshan, China earthquake of
1976, in which at least 255,000 were killed; the earthquake of
1927 in Xining, Qinghai, China (200,000); the Great Kanto
earthquake which struck Tokyo in 1923
(143,000); and the Gansu, China,
earthquake of 1920 (200,000). The deadliest known
earthquake in history occurred in 1556 in
Shaanxi, China, with an estimated death toll of 830,000, though
figures from this time period may not be reliable.
The 2004 tsunami is the deadliest in recorded history. Prior to 2004, the
deadliest recorded tsunami in the Pacific Ocean was in 1782, when 40,000 people were killed by a
tsunami in the South
tsunami created by the 1883 eruption of Krakatoa is thought to have resulted in
36,000 deaths. The most deadly tsunami between 1900 and
2004 occurred in 1908 in Messina, Italy, on the
Mediterranean Sea, where the earthquake and tsunami killed
70,000. The most deadly tsunami in the Atlantic
Ocean resulted from the 1755 Lisbon earthquake, which, combined with the toll from the actual
earthquake and resulting fires, killed over 100,000.
The 2004 earthquake and tsunami combined have been described as the
deadliest natural disaster
either the 1976 Tangshan
or the 1970 Bhola
, or could conceivably exceed both of these. Because of
uncertainty over death tolls, it might never be known for sure
which of these natural disasters was the deadliest.
See also: Library
damage resulting from the 2004 Indian Ocean
Human component in magnitude of damage
Indonesians gather under an
approaching helicopter to receive food and supplies.
The human destruction of coral reefs
played a significant role in the destruction caused by the tsunami.
Many countries across Asia, including Indonesia, Sri Lanka and
Bangladesh, have put forth efforts to destroy the coral surrounding
their beaches, and instead make way for shrimp farms and other
economic choices. On the Surin Island
chain of Thailand's coast, many people were saved as the tsunami
rushed against the coral reefs protecting the islands. However,
there were many fewer people on these islands, which helps explain
the lower death toll. Many reefs areas around the Indian Ocean have
been exploded with dynamite because they are considered impediments
to shipping, an important part of the South Asian economy.
Similarly, the removal of coastal mangrove
trees is believed to have intensified the effect of the tsunami in
some locations. These trees, which lined the coast but were removed
to make way for coastal residences, might have blocked the force of
the tsunami. Another factor is the removal of coastal sand dunes
Humanitarian, economic and environmental impact
A great deal of humanitarian aid
was needed because of widespread damage of the infrastructure
, shortages of food and water,
and economic damage. Epidemics
special concern due to the high population density
and tropical climate
of the affected areas. The
main concern of humanitarian and government agencies was to provide
sanitation facilities and fresh drinking water to contain the
spread of diseases such as cholera
There was also a great concern that the death toll could increase
as disease and hunger spread. However, because of the initial quick
response, this was minimized.
In the days following the tsunami, significant effort was spent in
bodies hurriedly for fear of disease.
However, the public health
have been exaggerated, and therefore this may not have been the
best way to allocate resources. The World Food Programme
provided food aid
to more than 1.3 million people affected by the tsunami.
all over the world provided over US$7 billion in aid for damaged
regions, with the governments of Australia pledging US$819.9 million
(including a US$760.6-million aid package for Indonesia), Germany offering US$660 million,
Japan offering US$500 million,
Canada offering US$343 million,
Norway and The
both US$183 million, the United States offering
US$35 million initially (increased to US$350 million), and the
World Bank offering US$250
Also Italy offered US$ 95 million, increased later
to US$ 113 million of which US$ 42 million was donated by the
population using the SMS system According to USAID
, the US has pledged additional funds in
long-term U.S. support to help the tsunami victims rebuild their
lives. On February 9, 2005, President Bush asked Congress to
increase the U.S. commitment to a total of $
950 million. Officials estimated that
billions of dollars would be needed. Bush also asked his father,
former President George H. W. Bush, and former President Bill
Clinton to lead a U.S. effort to provide private aid to the tsunami
In mid-March the Asian
reported that over US$4 billion in aid
promised by governments was behind schedule. Sri Lanka reported
that it had received no foreign government aid, while foreign
individuals had been generous. Many charities were given
considerable donations from the public. For example, in the UK the
public donated roughly £330,000,000 sterling (nearly
US$600,000,000). This considerably outweighed the donation by the
government and came to an average of about £5.50 (US$10) donated by
In August 2006, fifteen local aid staff working on post-tsunami
rebuilding were found executed in northeast Sri Lanka after heavy
fighting, the main umbrella body for aid agencies in the country
said. There had been reports and rumors that the local aid workers
had been killed.
The impact on coastal fishing
and fisherfolk, some of the poorest people in the
region, has been devastating with high losses of income earners as
well as boats and fishing gear. In Sri Lanka artisanal fishery,
where the use of fish baskets, fishing traps, and spears are
commonly used, is an important source of fish for local markets;
industrial fishery is the major economic activity, providing direct
employment to about 250,000 people. In recent years the fishery
industry has emerged as a dynamic export-oriented sector,
generating substantial foreign exchange earnings. Preliminary
estimates indicate that 66% of the fishing fleet and industrial
infrastructure in coastal regions have been destroyed by the wave
surges, which will have adverse economic effects both at local and
But some economists believe that damage to the affected national
economies will be minor because losses in the tourism and fishing
industries are a relatively small percentage of the GDP
. However, others caution that
damage to infrastructure is an overriding factor. In some areas
drinking water supplies and farm fields may have been contaminated
for years by salt water from the ocean.
earthquake and the tsunami may have affected shipping in the
Straits by changing the depth of the seabed and by
disturbing navigational buoys and old shipwrecks.
new navigational charts may take months or years.
Countries in the region appealed to tourists to return, pointing
out that most tourist infrastructure is undamaged. However,
tourists were reluctant to do so for psychological reasons. Even
resorts on the Pacific coast of Thailand, which were completely
untouched, were hit by cancellations.
the heavy toll on human lives, the Indian Ocean earthquake has caused an
enormous environmental impact that will affect the region for many
years to come.
It has been reported that severe damage has
been inflicted on ecosystems
, coastal wetlands
formations, animal and plant biodiversity
. In addition, the spread of solid
and liquid waste and industrial chemicals, water pollution
and the destruction of
collectors and treatment plants
threaten the environment even further, in untold ways. The
environmental impact will take a long time and significant
resources to assess.
According to specialists, the main effect is being caused by
poisoning of the freshwater
the soil by saltwater
deposit of a salt
layer over arable land. It
has been reported that in the Maldives, 16 to 17 coral reef atolls
that were overcome by sea waves are totally without fresh water and
could be rendered uninhabitable for decades. Uncountable wells that
served communities were invaded by sea, sand and earth; and
were invaded through porous rock.
Salted-over soil becomes sterile, and it is difficult and costly to
restore for agriculture
. It also causes
the death of plants and important soil micro-organisms. Thousands
of rice, mango and banana plantations in Sri Lanka were destroyed
almost entirely and will take years to recover.The United Nations Environment
(UNEP) is working with governments of the region in
order to determine the severity of the ecological impact and how to
address it. UNEP has decided to earmark a US$1,000,000 emergency
fund and to establish a Task Force to respond to requests for
technical assistance from countries affected by the tsunami. In
response to a request from the Maldivian Government
Australian Government sent ecological experts to help restore
marine environments and coral reefs—the lifeblood of Maldivian
tourism. Much of the ecological expertise has been
rendered from work with the Great Barrier Reef, in Australia's northeastern waters.
Many health professionals and aid workers have reported widespread
psychological trauma associated with the tsunami. Traditional
beliefs in many of the affected regions state that a relative of
the family must bury the body of the dead, and in many cases, no
body remained to be buried.
hardest hit area, Aceh, is
considered to be a religiously conservative Islamic society and has had no tourism nor any Western
presence in recent years due to armed conflict
between the Indonesian military
and Acehnese separatists.
Some believe that the tsunami was divine punishment for lay
shirking their daily prayers and/or
following a materialistic lifestyle. Others have said that Allah
was angry that there were Muslims killing other
Muslims in an ongoing conflict. Women in Aceh required a special
approach from foreign aid agencies, and continue to have unique
In what may be the most significant positive result of the tsunami,
the widespread devastation led the main rebel group GAM
to declare a cease-fire on December
28, 2004, followed by the Indonesian government, and the two groups
resumed long-stalled peace talks, which resulted in a peace
agreement signed August 15, 2005. The agreement explicitly cites
the tsunami as a justification.
The extensive international media coverage of the tsunami, and the
role of mass media and journalists in reconstruction, were
discussed by editors of newspapers and broadcast media in
tsunami-affected areas, in special video-conferences set up by the
Asia Pacific Journalism
The December 26, 2004 Asian Tsunami left both the people and
government of India in a state of heightened alert. On December 30, 2004,
four days after the tsunami, the Portland, Oregon-based company Terra Research notified the India
government that its sensors indicated there was a possibility of
7.9 to 8.1 magnitude tectonic shift in the next 12 hours between
Sumatra and New Zealand. In response, the India Home Affairs minister
announced that a fresh onslaught of deadly tidal waves were likely
along the India southern coast and Andaman
Islands, even as there was no sign of turbulences in the
The announcement generated panic in the Indian Ocean
region and caused thousands to flee their homes, which resulted in
jammed roads. The announcement was a false alarm and the Home
Affairs minister withdrew their announcement. On further
investigation, the India government learned that the consulting
company Terra Research was run from the home of a self-described
no telephone listing and maintained a website where he sold copies
of his detection system. Three days after the announcement,
Indian National Congress
president Sonia Gandhi
called Science &
minister Kapil Sibal
express her concern about Sibal's December 30 public warning being
result of the tsunami, respective toward Indian culture, was the
water that washed away centuries of sand from some of the ruins of
a 1,200-year-old lost city at Mahabalipuram on the south coast of India.
containing such notable structures as a half-buried granite lion
near a 7th century Mahablipuram temple and a relic depicting an
elephant, is part of what archaeologists believe to be an ancient
port city that was swallowed by the sea hundreds of years
The tsunami had severe a humanitarian and political impact in
Sweden. The hardest hit country outside Asia, 543 Swedish tourists,
mainly in Thailand, died. With no single incident having killed more
Swedish people since the battle of Poltava in 1709, the cabinet of Göran Persson was
heavily criticized for lack of action.
The event was
examined by an independent inquiry, Katastrofkommissionen
Göran Persson lost the 2006 election.
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Scientific and educational
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Indian Ocean Tsunami: Field Perspectives on the Impacts to the
Peoples, Cultures, Politics, and Economies of One of the World's
Most Vibrant Regions, Speaker: Tom Casadevall, September 26,
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