Millions breathe sigh of relief after tsunami alert is lifted following double quake that spread panic from Indonesia to India
Apr 12, 2012
- Alert lifted after experts reveal quakes were wrong type to cause tsunamis
- Warning first issued after 8.7 magnitude quake strikes off Aceh coast
- Magnitude 8.2 aftershock hits two hours later
- Fears of repeat of 9.1 disaster in 2004, which killed 230,000 people
- Panic in streets as buildings shake for four minutes and people flee to hills
- David Cameron was visiting Indonesia when quakes struck
Millions of people living along the coastline of the Indian Ocean were left breathing a sigh of relief today after warnings of a devastating tsunami were lifted following two massive earthquakes.
Panic spread across the region after an 8.7 magnitude tremor struck 270 miles off the Indonesian province of Aceh - which bore the brunt of the Boxing Day tidal wave of 2004.
Tsunami warnings were instantly issued in Indonesia, India, Sri Lanka, Australia, Burma, Thailand, the Maldives, Malaysia, Pakistan, Somalia, Oman, Iran, Bangladesh, Kenya, South Africa and Singapore.
In the Indonesian city of Banda Aceh, terrified residents screamed 'God is great!' as they jumped into cars and the backs of motorcycles, clogging streets as they fled to high ground.
Rush: Clogged streets in Banda Acey as people
grab whatever vehicles they can find and head to the hills. There were
fears that a tsunami could be as bad as the one on Boxing Day in 2004
Panic: People in Banda Aceh scramble to ecsape the city after a tsunami warning was issued
Patients also poured out of hospitals, some with drips still attached to their arms. In some places, electricity was briefly cut.
There were also scenes of panic in Bangalore, India and Columbo in Sri Lanka as terrified people fled their homes and offices.
Then, two hours later, a massive aftershock - with a similarly huge magnitude of 8.2 - struck only 110 miles further out to sea, unleashing even more panic.
Tsunami waves, measuring 3ft in height, hit Sumatra, the island Aceh is on. But experts discovered that both quakes were the wrong type to issue a disaster and the warnings were lifted.
Rush: Residents of Banda Aceh evacuate following a tsunami warning after two massive earthquakes
Piled up: A father loads his wife and four children on to his moped and drives off
The tsunami triggering 9.1-magnitude earthquake of seven years go - which killed 230,000 people, three quarters of whom lived in Aceh - was a thrust quake, which causes the sea bed to flip up.
The earthquakes occurred as Prime Minister David Cameron visited Indonesia's capital, Jakarta, which is 1,600 miles south-east of Aceh and on a different island, Java. No tremors were felt there.
He told President Susilo Bambang Yudhoyono: ‘Our thoughts should be with those who are affected.
‘Britain of course stands ready to help if help is required.
‘We will stand with you and your government and your people at this time of worry.
Fears: Lines in the ocean show how far tsunami waves could travel in just a few hours
Impact: Both quakes hit just a few hundred miles
off the coast of Aceh. The first hit at 8.38am GMT. It was followed by a
massive aftershock (marked 2) at 10.43am GMT. The black star indicates
the epicentre of the 2004 earthquake that triggered a devastating
tsunami. The region is prone to tsunamis because there are several
tectonic plates moving about on the floor of the expansive Indian Ocean,
pictured right
Strike point: The spot where the earthquake hit. The bubbles represent previous quakes
Frail: An elderly woman is helped by her family as they attempt to flee the city
Elsewhere: Tourists in Phuket, southern Thailand head to high ground amid fears a tsunami could strike there again
Moving out: Sri Lankans leave their houses after
the government announced a tsunami warning. It was later repealed along
with most other countries in the Indian ocean
Leaving: Office workers evacuate from buildings in Colombo, Sri Lanka after tremors were felt there
Gone in a blur: Acehnese people escape in motorcycles and tuk tuks
Concern: An Acehnese woman with a child tries to stop a car to go to higher ground after tremors are felt
He added that ‘as of this time there is no threat of tsunami’ - despite an international warning being issued.
He added: ‘The situation is under control so far. It is a very different situation from 2004 when Aceh was faced with a deadly tsunami.’
The tremor was felt in Singapore, Thailand, Bangladesh, Malaysia and India. A tsunami warning has been issued for cities all along the coast of Sumatra.
Visit: David Cameron talks to Indonesian
President Susilo Bambang Yudhoyono after his arrival at the Presidential
Palace in Jakarta today
There were also reports of the water level dropping in the Thai resort of Phuket - a sign that the sea is drawing back in preparation to launch an enormous wave.
A tsunami watch means there is the potential for a tsunami, not that one is imminent. Since 2004 such warnings are issued after every earthquake in the Pacific.
Indonesia straddles a series of fault lines that makes the vast island nation prone to volcanic and seismic activity.
Last year's devastating tsunami in Japan was triggered by an earthquake with a similar hypocentre depth 20 miles below the surface.
Chilling parallels with Boxing Day disaster that devastated an entire region... and gave rise to new tsunami warning system
The earthquake that struck off the coast of Aceh today has chilling parallels with the disaster that obliterated the region on Boxing Day, 2004.
More than 230,000 thousand people were killed by the resulting tsunami that swept inland and washed away homes.
A further 250,000 people were injured by the catastrophe, which was the sixth deadliest ever recorded.
But so unpredictable is the whim of nature that today's earthquake - despite being almost as powerful - has not had the same fatal effects.
The tsunami that struck in the Indian Ocean in 2004, was caused by a 9.1 magnitude earthquake. Today's earthquake measures 8.7 on the Richter scale.
Damage: Residents are swept away in the
raging torrents that engulfed parts of Sri Lanka after the earthquake
off the coast of Indonesia in 2004. The quake was more catastrophic than
the recent one
Flood waters in Thailand lap around the damage homes that were crushed by the tsunami that struck off Indonesia in 2004
Power: A wall of water crashes over a street in Miyako City, Japan during last year's devastating tsunami there
The biggest tsunami ever recorded was triggered by an 8.3 magnitude earthquake in Lituya Bay, Alaska on July 9, 1958 - less powerful than the most recent quake in Indonesia.
So why has today's quake not caused a killer tsunami?
The quake struck 20.5 miles below the sea bed whereas the one in 2004 was slightly closer to the sea at just 19 miles.
However, due to continual movement of the plates over the last eight years there position today will be different to when disaster struck before. The position of the plates when one of them breaks and causes seismic waves is a vital part of what causes the tsunami.
Although both earthquakes formed on the fault line where the India and Burma plates meet, today's earthquake did not cause disruption in the water.
Roger Musson, seismologist at the British geological survey who has studied the fault lines off Sumatra in northern Indonesia said that today's tremor was a strike-slip quake, not a thrust quake which causes the sea bed to flip up.
It is not impossible for strike-slip earthquakes to generate vertical uplift of water,
'When I first saw this was an 8.7 near Sumatra, I was fearing the worst,' Mr Musson said.
'But as soon as I discovered what type of earthquake it was, then I felt a lot better.'
Mega tsunamis strike when the plates create changes in the water pressure. The plates will have moved under each other differently today than how they did in 2004, creating less change in the water pressure.
Moreover, researchers studying the 2004 quake found small but significant jumps of between 5 and 10 millimeters at stations as far as 3000 kilometres from the epicentre. They also found the rupture was 1000km long and spread rapidly northwards from its origin.
In this case it appears that even though an underwater earthquake has been recorded, the disruption to the sea bed has not been strong enough to create momentum in the water.
The analyusts from Ecole Normale Supérieure (ENS) in Paris studied GPS data showing that the damage caused by the earthquake was at least 200km north of its epicentre.
The severity and location of the damage to seabed caused by today's earthquake is still unclear.
Following the damage, The Indian Ocean Tsunami Warning System was established following a United Nations conference in Kobe, Japan, in January 2005.
Seventeen seismic stations were placed in the ocean to detect plate movements and tremors. These sensors then pass the information to two recording stations which sound sirens and even make automated phone calls and send text messages and emails to residents.
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