(The Guardian) — A large earthquake shook the Indonesian island of Sumatra on Wednesday, causing widespread panic and fear of a repeat of the 2004 earthquake and series of tsunamis that killed 230,000 people.
The 8.6-magnitude earthquake struck the seabed 300 miles west of Banda Aceh, the island's provincial capital, at 3.38pm local time, and was followed by an 8.2-magnitude aftershock just two hours later, causing locals to scramble for higher ground as traffic jams, power cuts and the sound of sirens and Qur'an recital calls created an atmosphere of chaos, according to Reuters.
The tremor passed without any immediate reports of casualties or major damage, and was met with greater public awareness and successful earthquake drills.
Residents in Banda Aceh, some of whom holed up in mosques to pray while others fled to nearby hills on the back of motorbikes, said the ground shook violently for up to five minutes, causing widespread fear about the potential aftermath. "We were afraid that it was a signal that a tsunami would hit the area," one resident told the Jakarta Post.
Another said that most residents were able to handle the situation calmly.
"Unlike in 2004, when the strong earthquake hit Aceh early in the morning, many people were still sleeping so most of us were not ready," Jauhari of the Indonesia Community Radio Networks said.
"This time, the earthquake occurred at a busy hour when most people were awake, so people just left buildings and went to safe places."
Tremors were felt as far away as India, Sri Lanka, Vietnam and Singapore, with Twitter reports of office workers scurrying from their buildings in panic and tourists in beach resorts on the Thai island of Phuket worried over approaching tsunamis.
Tsunami waves of three to four metres were expected in Phuket, which was badly damaged in the 2004 tsunami, but an island-wide system of tsunami warnings saw local residents and tourists calmly evacuating. Thai officials temporarily closed Phuket airport and also issued warnings for other coastal provinces.
"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," freelance journalist Apichai Thonoy told Reuters. "Everyone seemed quite calm. The warning had been issued well in advance."
The US Pacific Tsunami Warning Centre lifted its Indian Ocean-wide tsunami warning later on Wednesday afternoon to read that "level readings now indicate that the threat has diminished or is over for most areas".
Indonesia, India, Thailand and Sri Lanka dropped their tsunami warnings, although Kenya and Tanzania were still on alert along their Indian Ocean coastlines on Wednesday afternoon.
Indonesian president Susilo Bambang Yudhoyono said there was no threat of a tsunami after the earthquake hit and told local reporters that "the situation in Aceh is under control". There were no immediate reports of casualties or damage in Aceh either, he said. "Our warning system is working well, and I have ordered the national relief team to fly immediately to Aceh to ensure the situation is under control and to take any necessary action," he said.
At least three tsunamis of up to 80cm reportedly hit Indonesia's coastlines, although a tsunami as destructive as that in 2004 was unlikely, according to officials. The US Geological Survey told the BBC that such a tsunami was improbable because Wednesday's quake was caused by the earth moving horizontally instead of vertically.
South-east Asia analyst Maria Patrikainen of IHS said that while the Indonesian government had increased its efforts to tackle natural hazards since the 2004 tsunami, many provinces still lack resources equipped to deal with natural disasters.
"Since the inauguration of the tsunami warning system in 2008, concerns have been raised that the inadequate training of the officials operating the system could lead to malfunctions," Patrikainen said. "Also, there have been reports of vandalism of supporting equipment, with several buoys broken, missing, or stolen."
Earthquakes in Indonesia are common due to its location on the ring of fire, a series of fault lines which make the archipelago nation of roughly 18,000 islands prone to volcanic and seismic activity.
Nearly three-quarters of the people killed in the 9.1-magnitude quake that occurred on Boxing Day 2004 were in Aceh.