|coast of Africa, with the furthest recorded death due to the tsunami occurring at Port Elizabeth in South Africa, 8,000km away from
Anywhere from 165,000 to 310,000 people are thought to have died as a result of the tsunami, and the count is not yet complete.
The true final toll may never be known due to bodies having been swept out to sea, but current estimates use conservative
It also caused the Earth to minutely "wobble" on its axis by up to 2.5 cm in the direction of
145° east longitude or perhaps by up to 5 or 6 cm. However, due to tidal effects of the Moon,
the length of a day increases slightly anyway so any rotational change due to the earthquake
will be lost quickly.
More spectacularly, some of the smaller islands south west of Sumatra may have moved
southwest by up to 20 m. The northern tip of Sumatra, which is on the Burma Plate, may also
have moved up to 36 m southwest. Movement was likely both vertical as well as lateral; some
coastal areas may now be below sea level.
The sudden vertical rise of the seabed by several metres during the earthquake displaced massive volumes of
water, resulting in a tsunami that struck 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 motion.
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 travels at very high
speed (500-1,000 km/h); in shallow water near coastlines, a tsunami slows down to only tens of kilometres an
hour but in doing so forms large destructive waves.
The hypocentre of the main earthquake was some 160 km west of Sumatra, at a depth of 30 km below
mean sea level (initially reported as 10 km). This is at the extreme western end of the Ring of Fire, an
earthquake belt that accounts for 81 percent of the world's largest earthquakes.
Radar satellites recorded the heights of tsunami waves in deep water: at two hours after the earthquake, the maximum height was 60 cm. These are the first such observations ever
made. Theses observations could not be used to provide a warning, because the satellites were not intended 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 about five megatons of TNT. 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 inland.
Due to the distances involved, the tsunami took anywhere from fifteen minutes to seven hours (for Somalia) to reach the various coastlines. The 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.
It was noticed as far as Struisbaai in South Africa, some 8,500km away, where a 1.5 metre high ‘tide’ surged onshore about 16 hours after the quake. It took the tsunami a relatively
long time to reach this spot at the southernmost point of Africa, probably due to the broad continental shelf off South Africa and the fact that the tsunami would have followed the
South African coast from east to west.
|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, and equally importantly, warn the general populace living around the ocean quickly. Tsunami detection is not easy
because while a tsunami is in deep water it has a very low 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.
Scientists were also hampered by the fact that the initial estimate for the magnitude of the earthquake was 8.1. The determination that the earthquake had actually been much
stronger (and the resulting tsunami much larger) was not made until after the tsunami had already struck.
Tsunamis usually occur in the Pacific Ocean due to earthquakes in the "Ring of Fire", 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 due to the rarity of tsunamis
there; the last major one was caused by the Krakatoa eruption of 1883.
In the aftermath of the disaster there is a new awareness of the need for a tsunami warning system for the Indian Ocean. The UN has started working on an Indian Ocean Tsunami
Warning System and aims to have initial steps in place by end 2005.
|Some have 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, tsunamis can strike thousands of miles 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. People in Pacific regions are more familiar with tsunamis and often recognize this
phenomenon as a sign to head for higher ground. However, 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 of exposed beach, with fatal results.
One of the few coastal areas to evacuate ahead of the tsunami was on the Indonesian island of Simeulue, very close to the epicentre. Island folklore recounted an earthquake and
tsunami in 1907 and the islanders fled to inland hills after the initial shaking — before the tsunami struck.
On Maikhao beach in northern Phuket, Thailand, a 10 year old British girl named Tilly Smith had studied tsunamis in geography class at school and recognised the warning sign of
the receding ocean. She and her parents warned others on the beach, which was evacuated safely.
|A tsunami (pronounced su - na - mi) is a natural phenomenon consisting of a series of waves generated when water in a lake or the sea is rapidly displaced on a massive scale.
Earthquakes, landslides, volcanic eruptions and large meteorite impacts all have the potential to generate a tsunami. The effects of a tsunami can range from unnoticeable to
The term tsunami comes from the Japanese language meaning harbour and wave. The term was created by fishermen who returned to port to find the area surrounding the harbour
devastated, although they had not been aware of any wave in the open water. A tsunami is not a sub-surface event in the deep ocean; it simply has a much smaller amplitude
(wave heights) offshore, and a very long wavelength (often hundreds of kilometres long), which is why they generally pass unnoticed at sea, forming only a passing "hump" in the
Tsunamis were historically referred to as tidal waves because as they approach land they take on the characteristics of a violent onrushing tide rather than the sort of cresting
waves that are formed by wind action upon the ocean (with which people are more familiar). However, since they are not actually related to tides the term is considered
misleading and its usage is discouraged by oceanographers.
LONDON, March 28 (Reuters) - An earthquake that struck off the coast of northern Sumatra on Monday was measured by the U.S. Geological Survey at magnitude 8.7, making it one
of the eight biggest quakes since 1900 by magnitude.
Here is a list of the 12 strongest quakes since 1905:
May 22, 1960 - Chile - An earthquake measuring 9.5 struck the coast of central Chile, triggering tidal waves and volcanic eruptions. Some 5,000 people were killed and 2 million
March 28, 1964 - Alaska - An earthquake and ensuing tsunami claimed 125 lives and caused about $311 million in property loss. The quake, measuring 9.2, was felt over a large
area of Alaska and in parts of western Yukon Territory and British Columbia, Canada.
March 9, 1957 - Alaska - An earthquake measuring 9.1 hit the Andreanof Islands. On Umnak Island, Mount Vsevidof erupted after being dormant for 200 years, generating a 15-metre
high tsunami that continued to Hawaii.
Dec 26, 2004 - Indonesia - A quake measuring 9.0 struck the coast of Aceh province on the northern Indonesian island of Sumatra and triggered a tsunami that left nearly 300,000
people dead or missing across Sri Lanka, Thailand, Indonesia and India.
Nov 4, 1952 - Russia - An earthquake with a magnitude of 9.0 generated a tsunami that struck the Hawaiian islands. No lives were lost.
Jan 31, 1906 - Ecuador - An earthquake with a magnitude of 8.8 struck near the coast of Ecuador and Colombia, generating a strong tsunami that killed up to 1,000. It was felt all
along the coast of Central America and as far north as San Francisco and west to Japan.
March 28, 2005 - Indonesia - An earthquake of magnitude 8.7 struck off the coast of northern Sumatra, not far from the epicentre of the magnitude 9.0 quake three months earlier.
Feb 4, 1965 - Alaska - Measuring 8.7, the quake generated a tsunami reported to be about 10.7 metres high on Shemya Island.
Aug 15, 1950 - Tibet/India - Two thousand homes, temples and mosques were destroyed in a quake measuring 8.6. Hardest hit was the Brahmaputra Basin in northeast India. At
least 1,500 people were killed.
Feb 3, 1923 - Russia - The Kamchatka peninsula was struck by a quake with a magnitude of 8.5.
Feb 1, 1938 - Indonesia - An 8.5 magnitude earthquake in the Banda Sea generated tsunamis that caused great damage on Banda and Kai, volcanic islands in eastern Indonesia.
Oct 13, 1963 - Kurile Islands - A quake measuring 8.5 was recorded in the island chain, which stretches from Russia to Japan.
"Waves were more than twice the total explosive energy used during all of
World War II"
The 2004 Indian Ocean earthquake occurred undersea at
00:58:53 UTC (07:58:53 local time) on December 26 2004.
The earthquake generated a tsunami that was among the
deadliest disasters in modern history.
At a magnitude of 9.0, it was the largest earthquake since the
9.2 magnitude Good Friday Earthquake off Alaska in 1964,
and tied for fourth largest since 1900.
The earthquake originated in the Indian Ocean just north of
Simeulue island, off the western coast of northern Sumatra,
The resulting tsunami devastated the shores of Indonesia, Sri
Lanka, South India, Thailand and other countries with waves of
up to 15 m (50 feet) high.
It caused serious damage and deaths as far as the east
The total energy released by the earthquake in the Indian Ocean has been estimated
as 2.0 exajoules.
This is enough to boil 150 litres of water for every person on Earth. It is estimated
to have resulted in an oscillation of the Earth's surface of about 20 to 30 cm. The
shock waves of the earthquake were felt across the planet - as far away as
Oklahoma, vertical movements of 3 mm were recorded.
The shift of mass and the massive release of energy very slightly altered the Earth's
rotation. The exact amount is yet undetermined, 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.
The Thai Meteorological Department acting Director General Chalermchai Ekkantrong said last night his agency had issued tsunami warnings to provinces on the coast of the Andaman
Sea in wake of the quake.
“Considering such a high magnitude of the quake, it could cause tsunami,” he said.
The quake triggered commotion particularly in six southern provinces struck by tsunami on Dec 26 last year.
On Phuket, Patong Beach residents and tourists rushed out of their houses and hotels to take any vehicles they could find to get away from the beachfront.
“I can hear cars roaring everywhere. The streets just turn into mess. Now I have to rush out of the hotel,” a local TV reporter said in her live report.
“The building is so badly shaken that I can’t keep myself standing,” recounted the Nation’s reporter Achara Pongvuthitham, who was on the 25th floor of the 33-storey Lee Garden
Hotel in Songkhla’s Hat Yai district.
Achara said she and many other guests ran down the fire stairs to the street down below and saw debris of broken cement and glasses along the way.
Hotel workers tried to help many guests who were locked in elevators.
Three main roads in Hat Yai were crowded with people who fled from the sheaking buildings. Traffic in the town was in serious trouble due to congestion after panic.
The quake was also felt in tall buildings in Bangkok and other provinces.
India has reactivated an emergency control room following an earthquake measuring 8.2 on the Richter scale off the coast of Indonesia, fearing a fresh tsunami disaster, official
Top officials of the meteorological department were working to find out whether the quake could trigger a tsunami, the sources said, according to the Press Trust of India.
The emergency control room was set up following the December 26 earthquake which sent tsunamis crashing all along the Indian coast killing thousands.
District officials in southern India told television channels that they were awaiting instructions from the home ministry, which runs the control room, for any evacuation that needs
to be done.
Met department officials in New Delhi said "an earthquake has occurred" but had no immediately details.
--The Nation, Agencies 2005-03-29
CNN) -- Fifty people were killed and about 300 homes were destroyed on the island of Nias, near the epicenter of a massive earthquake that struck off the coast of Indonesia on
Monday, a government official there told CNN.
Meanwhile, a tidal gauge has detected a small tsunami in the Indian Ocean several hundred miles southwest of the earthquake
Scientists say the threat of a tsunami striking Indonesia and Thailand may have passed because a wave like the one that hit the region on December 26 would have reached those
countries almost immediately. Monday's quake struck at 11:09 a.m. ET (1609 GMT).
PHUKET Gazette 29 March 2005;
Seaside towns and villages around Phuket were evacuated last night after warnings from the Meteorological Department that there was a high possibility of another tsunami hitting
The warnings came after a massive earthquake jolted Sumatra, just 200 kilometers from the site of the temblor that caused the tsunami on December 26 last year. That wave killed
an estimated quarter-million people around the rim of the Indian Ocean, including 5,395 in Thailand.
In the event, last night’’s quake, reported as registering 8.7 on the Richter scale by the US Geological Survey (USGS), caused no tsunami, though it did take some 300 lives on Nias,
the Indonesian island closest to the epicenter of the jolt. (For more details of the quake, see here)
The USGS, contacted by the Gazette immediately after the quake, described it as a “great” quake, an d advised that it was strong enough to cause “wave motion”.
The earthquake, to the southwest of Sumatra at about 11:15 pm, rocked Malaysia and southern Thailand, and was felt as far away as Bangkok, where tall buildings swayed.
Within minutes, Thai TV channels were receiving SMS messages from viewers. The warning from the Meteorological Department followed soon afterward, advising that there was a
growing likelihood of a tsunami, and urging anyone near the sea to head for higher ground immediately.
The message was relayed by people with mobile phones to the point that within half an hour or so the network was jammed. Government officials went around banging on doors, as
did ordinary people.
In Phuket City, some 300 people from Saphan Hin, Koh Sireh and other low-lying parts gathered at Phuket Provincial Hall. Others climbed Toh Sae Hill and Rang Hill. In Patong, most
people moved to the mountains that surround the town on three sides.
Pol C ol Teeraphol Thipjaroen, Superintendent of Kathu Police Station, which is in Patong, told the Gazette that as soon as he learned about the warning, his officers and officials
from the Patong Municipality went about telling people to move to higher ground immediately.
“The warning system that was just installed was also working well last night,” he added, saying that he believed that almost everyone in Patong had been evacuated.
A Gazette reader who was in Kalim around the time of the earthquake heard the alerts being issued in Patong about an hour after the quake.
She said, “They were loud enough to be heard in Kalim, so they must have been very loud in Patong.
“I was indoors, so I don’t know whether people were panicking, but there seemed to be a lot of cars driving away from Patong towards the higher ground in Kalim.”
In Phuket City, Provincial Governor Udomsak Usawarangkura convened an emergency meeting at 1 am at the Phuket Provincial H all.
After the meeting he said, “We recommend that people who do not live next to the water stay at home and listen for news from the government. If people go out, it will only add to
“There has been a problem with telephone connections, especially by mobile phone. We will need some swift solutions from TOT.”
“Announcements have gone out by TV and radio. I have asked the police to watch people’s homes until everyone is evacuated.”
At 2.30 this morning, three hours after the quake, the Meteorological Department announced that there would be no tsunami after all, and Phuket went back to bed.
Asked how he thought last night’’s drama would affect tourism, the Governor said this morning, “There will certainly be an effect on tourism, so we have to make sure that tourists
know we have a good warning system. Japan often has earthquakes, yet it is still a major tourism destination.
“I believe we will see some cancelations of bookings, but I also think that the next high season, starting in November, will be good,” he added.
Sumatra shaken by new earthquake
A strong earthquake has struck near the Indonesian island of Sumatra, say seismologists.
The epicentre of the quake, which had an estimated magnitude of 6.7, was about 120km (75 miles) south-west of the city of Padang, officials said.
There were no immediate reports of damage, but some people fled the coast.
The latest tremor revived fears of a repeat of the 26 December tsunami disaster, which killed an estimated 300,000 people in a dozen countries.
Two-thirds of the deaths occurred in Indonesia.
However, no tsunami warning was issued on Sunday.
The latest tremor struck at struck at 1729 local time (1029 GMT) and was felt as far away as Singapore.
Many people were reported to have fled their homes in Padang, after a radio broadcast by city mayor Fauzi Bahar.
"Many people in Padang are panicking," said Yusuf, an official from Indonesia's Geophysics and Meteorology Agency (IGMA).
"People have left their houses, specially those living on the coast," he said, according to the Associated Press news agency.
The Pacific Tsunami Warning Center in Honolulu, in the US state of Hawaii, said: "Earthquakes of this size sometimes generate local tsunamis that can be
destructive along coasts located within a few hundred kilometres of the earthquake epicentre."
It urged local authorities to "be aware of this possibility and take appropriate action".
Scientists have warned that the Indian Ocean faultline could deliver another major earthquake, and tremors have been felt repeatedly in the area since the
9.3-magnitude jolt that unleashed the 26 December tsunami.
Two weeks ago, an aftershock from that earthquake killed more than 600 people on the Indonesian island of Nias.
On that occasion, rapid response plans put in place after December's disaster were activated promptly.
An integrated tsunami warning system for the region will not be ready until the end of next year, but most countries have a contingency plan.
Baan Nam Khem
Within the 30 mins of the Quake we were able to talk
to the head man at the Baan Nam Khem Fishing village.
They had already been made aware of what was
happening and were organising an evacuation of the
area. It was a frightening time but they were OK and
heading for higher ground.
Friends from Bangkok had already phoned to say that
they felt the quake for about 3 mins and that it seemed
stronger than on 26 December
|Magnitude 8.7 - NORTHERN SUMATRA, INDONESIA 2005 March 28 16:09:36 UTC
Preliminary Earthquake Report
U.S. Geological Survey, National Earthquake Information Center
World Data Center for Seismology, Denver
A great earthquake occurred at 16:09:36 (UTC) on Monday, March 28, 2005. The magnitude 8.7 event has been located in NORTHERN SUMATRA, INDONESIA.
Monday, March 28, 2005 at 11:09:36 PM = local time at epicenter
Date-Time Monday, March 28, 2005 at 16:09:36 (UTC) or GMT
Location 2.065°N, 97.010°E
Depth 30 km (18.6 miles) set by location program
Region NORTHERN SUMATRA, INDONESIA
205 km (125 miles) WNW of Sibolga, Sumatra, Indonesia
250 km (155 miles) SW of Medan, Sumatra, Indonesia
535 km (330 miles) WSW of KUALA LUMPUR, Malaysia
1410 km (880 miles) NW of JAKARTA, Java, Indonesia
At least 50 people killed, 100 injured and 300 houses Destroyed on Nias. Extensive damage on Simeulue. Felt in Indonesia, Malaysia, Singapore and as far north
as Bangkok, Thailand.