The quake was also felt in Sri Lanka and the southern Thai holiday island of Phuket, both of which were hit hard by the 2004 tsunami.
Indonesia straddles a series of fault lines that makes the vast island nation prone to volcanic and seismic activity.
According to the USGS, the 2004 quake struck about 155 south-southeast of Banda Aceh at a depth of 18.6 miles. Some 227,898 people were killed or missing presumed dead and about 1.7 million were forced out of their homes after the tsunami affected 14 countries in Asia and East Africa.
Indonesia's explosive geology explained
“This is the third largest earthquake in the world since 1900 and is the largest since the 1964 Prince William Sound, Alaska earthquake,” the USGS said in its summary about the 2004 earthquake.
“The tsunami caused more casualties than any other in recorded history and was recorded nearly world-wide on tide gauges in the Indian, Pacific and Atlantic Oceans,” it added.
The most severe earthquake since 1900 was of 9.5 magnitude and struck Santiago and Concepcion in Chile on May 22, 1960, triggering tidal waves and volcanic eruptions. Some 5,000 people were killed and 2 million made homeless.
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A tsunami alert was issued for the entire Indian Ocean Wednesday after a powerful 8.7-magnitude earthquake was recorded off Indonesia's coast.
The U.S. Geological Survey said the quake was centered 20 miles beneath the ocean floor and 308 miles from the provincial capital of Banda Aceh at 2:38 p.m. local time (3:38 am. ET). The quake is in a similar location and of a similar magnitude to the 9.1-magnitude tremor on Dec. 26, 2004 that triggered a tsunami in the Indian Ocean, killing 230,000 people, nearly three-quarters of them in Aceh province.
NBC News reported scenes of panic in Indonesia, with residents and even hospital patients fleeing buildings. It said tsunamis are hard to predict but are usually seen within 30 minutes of the tremor.
"The quake was felt very strongly. Electricity is down, there's traffic jams to access higher ground. Sirens and Koran recitals from mosques are everywhere," a spokesman for Indonesia's disaster mitigation agency told Reuters.
The Pacific Tsunami Warning Center issued a tsunami watch - an alert category one level below a warning - for countries as far apart as Sri Lanka, Pakistan, Somalia, Bangladesh and Singapore.
Reports on Twitter said Wednesday's tremors were felt in Singapore, Thailand, Malaysia and India. High-rise apartments and offices on Malaysia's west coast shook for at least a minute.
Evacuation orders were issued for southern Thai provinces of Phuket and Phangnga.
“The province has turned on the warning sirens and asked people all over Phuket island to move to a safe place,” an official from the Phuket Disaster Prevention and Mitigation Center told Reuters by telephone.
The country's National Disaster Prevention Center told NBC News that Phuket airport has been temporarily closed and flights diverted elsewhere.
India issued a tsunami alert for its eastern coast, causing panic and sending people fleeing onto the streets. Hundreds of office workers in the Indian city of Bangalore left their buildings, workers there said.
Indonesia's disaster mitigation agency is sending a rescue team to Aceh province, and said electricity had been cut to the area.
Simon Boxall, a U.K. oceanographer, told Sky News that the danger would not necessarily be over if the quake did not produce a tsunami.
“The initial earthquake may not cause a tsunami … [but] there’s no reason why an aftershock, which could still reach up to 8 in magnitude, cannot still cause a tsunami,” he added.
Boxall told Sky that not all offshore quakes produced tsunamis and issuing evacuation orders every time there was one could start to “get very messy.”
Amy Vaughn, a spokeswoman for the USGS, told the channel a tsunami similar in scale to the one in 2004 could be on its way. “Of course, being this close to the west coast of Sumatra, it could be very devastating to this coast again,” she said.
NBC News reported that quake has been rated as a '5' on the USGS MMI scale, which measures the physical intensity of an earthquake as felt on the ground. A strength 5 quake is defined as: "Felt inside by most, may not be felt by some outside in non-favorable conditions. Dishes and windows may break and large bells will ring. Vibrations like large train passing close to house."
India's tsunami warning center said waves measuring almost 20 feet were expected along parts of its eastern coast, which was heavily hit by the 2004 tsunami. Smaller waves were expected to hit the remote Andaman and Nicobar islands.
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Tornadoman78: tornadoman and tornadogirl like to kick box each other in my tornaolayzers and she dosent even mind getting hit