Tanzania yesterday issued a tsunami warning on its coastline after an 8.6 magnitude earthquake struck off the Indonesian coast, but downgraded it later in the day as the reported high waves receded.
The Tanzania's Meteorological Agency had earlier called upon coastal residents especially those in Lindi and Mtwara regions to take precautions as high waves were expected to impact part of the Indian Ocean. Fishermen and other vessels were urged to keep off the sea.
The agency’s Acting Director General, Dr Emmanuel Mpeta said in Dar es Salaam the tsunami waves, observed yesterday morning at around 11am at Sumatra Island in Indonesia, were expected to hit at 9:59pm.
The alert led to a panic in downtown Dar, compounding a serious traffic jam from on-going rains, as workers left offices early, apparently to be far away from the beach areas, where most government offices are located.
However responding to a follow-up call from The Guardian later in the evening, Dr Mpeta said the threat of tsunami waves on the country’s line had gradually receded, but the agency was still monitoring the situation closely.
He had earlier said that in Tanzania the tsunami waves were likely to hit Mtwara and Lindi regions, alerting coastal residents to temporarily vacate the area, explaining that the waves move very fast and can inflict serious damage within a short period.
“It is better for coastal residents to be attentive throughout the night”, said Dr Mpeta.
Kenya issued a similar warning following the quake yesterday. "The government of Kenya has consequently issued a tsunami warning for the people living along the Kenyan coastline," Esther Murugi, the minister of state for special programmes said in a statement.
"The water levels are expected to rise up to 2 to 3 metres in areas of Malindi, Lamu, up to Kiunga while in Kilifi, Mombasa up to Shimoni, the levels are expected to rise up to 2 metres," she said.
Some 164 people were killed and more than 2,300 were displaced in Kenya, Tanzania, Madagascar, Seychelles, and Somalia after the disastrous 2004 Asian tsunami.
The waves were expected to hit the Kenyan coast, a popular tourist destination, at about 1700 GMT, officials said. One person in Kenya was killed in the 2004 tsunami.
Senior Assistant Director at Kenya's Met office, Ali Mafimbo, said an alert had been issued to keep people on the lookout and to stay out of the sea once they saw water levels receding.
Madagascar's National Office for Disaster and Risk Management said they did not expect the tsunami to cause damage on the Indian Ocean island.
"We don't expect the wave to have a big impact on Madagascar. We are not planning to move anybody. We urge people not to panic," Louis de Gonzague Rakotonirainy said, before the latest wave of aftershocks.
"In the event the situation develops, the inhabitants of the east coast will be advised to move to higher ground. A meeting is taking place right now to evaluate the situation."
Parts of Indonesia's Sumatra island remained in danger from a tsunami following the powerful quakes off the Indonesian coast yesterday, but damage across the Indian Ocean basin is not expected, an official with the US Pacific Tsunami Warning Centre said.
"So far all we've seen is on the order of about a meter or three feet or so, peak-to-peak," said Barry Hirshorn, a geophysicist at the centre, referring to waves measured by gauges mounted on buoys.
"And we've observed that on our closest gauge to the actual epicentre. The gauge is just off northern shore of Sumatra," Hirshorn said. "We don't expect damage basin-wide, but there is danger nearby the source. So the tsunami danger is to the coastlines closest to the earthquake, which would be northern Sumatra."
Earlier the quake and strong aftershocks sent people as far away as southern India scurrying from buildings and raising fears of a disastrous tsunami as in 2004.
The first quake struck at 0838 GMT and an 8.2 magnitude aftershock just over two hours later, at 1043 GMT. Two more strong aftershocks hit later.
The Pacific Tsunami Warning Center issued fresh tsunami warnings for the entire Indian Ocean after the aftershocks. Authorities in Indonesia said there were reports of sea-levels rising off Aceh, but by less than a metre (3.3 feet).
But authorities in India's Andaman and Nicobar islands, to the north of where the quakes struck, said waves of up to 3.9 metres (13 feet) could hit there.
Individual countries, including Thailand, Indonesia, Sri Lanka and India, issued their own tsunami warnings and people near the coast in six Thai provinces were ordered to move to higher ground. Authorities shut down the international airport in the Thai beach resort province of Phuket.
The quakes were about 300 miles (500 km) southwest of the city of Banda Aceh, on the northern tip of Indonesia's Sumatra island, the US Geological survey said. The first was at a depth of 20.5 miles (33 km).
Indonesia's disaster management agency said power was down in Aceh province and people were gathering on high ground as sirens warned of the danger.
"The electricity is down, there are traffic jams to access higher ground. Sirens and Koran recitals from mosques are everywhere," said Sutopo, spokesman for the agency.
Indonesian President Susilo BambangYudhoyono, speaking after the first quake, said there were no signs of a disaster.
"There is no tsunami threat although we are on alert," he said at a joint news conference in Jakarta with visiting British Prime Minister David Cameron, who said Britain was standing ready to help if needed.
"The situation in Aceh is under control, there's a little bit of panic but people can go to higher ground," Yudhoyono said.
Warning sirens rang out across the Thai island of Phuket, a tourist hotspot that was one of the worst hit areas in the 2004 tsunami.
"Guests from expensive hotels overlooking Phuket's beaches were evacuated to the hills behind and local people were driving away in cars and on motorcycles. Everyone seemed quite calm, the warning had been issued well in advance," freelance journalist Apichai Thonoy told Reuters by telephone.
Indonesian television showed people gathering in mosques in Banda Aceh. Many others were on the streets, holding crying children.
In the city of Medan, a hospital evacuated patients, who were wheeled out on beds and in wheelchairs.
Yudhoyono said he had ordered a disaster relief team to fly to Aceh, which was devastated by the 9.1 magnitude 2004 quake, which sent huge tsunami waves crashing into Sumatra, where 170,000 people were killed, and across the Indian Ocean.
In all, the 2004 tsunami killed about 230,000 people in 13 Indian Ocean countries, including Thailand, Sri Lanka and India.
Yesterday's quakes were felt as far away as the Thai capital, Bangkok, and in southern India, hundreds of office workers in the city of Bangalore left their buildings while the port of Chennai closed down because of tsunami fears.
The quakes were in roughly the same area as the 2004 quake, which was at a depth of 18 miles (30 km) along a fault line running under the Indian Ocean, off western Indonesia and up into the Bay of Bengal.
One expert told the BBC at least yesterday's first quake was a "strike-slip" fault, meaning a more horizontal shift of the ground under the sea as opposed to a sudden vertical shift, and less risk of a large displacement of water triggering a tsunami.
The quakes were also felt in Sri Lanka, where office workers in the capital, Colombo, fled their offices.
Mahinda Amaraweera, Sri Lanka's minister for disaster management, called for calm while advising people near the coast to seek safety.
"I urge the people not to panic. We have time if there is a tsunami going to come. So please evacuate if you are in the coastal area and move to safer places," Amaraweera told a private television channel.
In Bangladesh, where two tremors were felt, authorities said there appeared to be no threat of a tsunami. Australia also said there was no threat of a tsunami there.
Meanwhile small tsunami waves of around one metre hit the western coast of Indonesia's Sumatra island on Wednesday after a series of major earthquakes, though the country's disaster agency said it was still assessing whether there were any deaths or damage.
The agency expects the worst impact to have been on Simeulue island off Sumatra and forecasts further small aftershocks in the country's westernmost region, but it has lifted its tsunami alert for an area which was devastated by a tsunami in 2004.
Apart from Tanzania the tsunami is likely to hit the following areas, Indonesia, India, Australia, Srilanka, Myanmar, Thailand, Maldives, UK, Malaysia, Mauritius, Reunion, Seychelles, Oman, Pakistan, Somalia, Madagascar, Iran, UAE, Yemen, Comoro, Mozambique, Kenya, Crozet Island, Bangladesh, Kerguelen Islands, South Africa and Singapore.