Quake kills at least 300 on Indonesian island
Vice president says up to 2,000 could be dead
(CNN) -- A major earthquake struck off the west coast of Indonesia late Monday, killing hundreds, but fears of another tsunami like those that devastated the region in late December have faded.
On Indonesia's Nias Island at least 300 people died and hundreds more were reported injured or trapped, said government spokesman Agus Mendrova.
But international news agencies are reporting that between 1,000 and 2,000 people may have been killed on Nias Island.
"It is predicted -- and it's still a rough estimate -- that the number of the victims of dead may be between 1,000 and 2,000," Vice President Jusuf Kalla told the el-Shinta radio station, according to The Associated Press.
Between 500 and 1,000 homes were destroyed, and the island's public market was ablaze, Mendrova said.
Between 10,000 and 15,000 people ran to hilltops for safety in case of a tsunami, Mendrova said. Many of the doctors and nurses who normally would staff the hospital fled to higher ground.
"We have not heard of any tsunami hitting anywhere," Jan Egeland, the U.N. emergency relief coordinator, told CNN from New York nearly six hours after the temblor struck.
Still, Egeland said, the earthquake itself was responsible for casualties on islands close to the epicenter.
Dozens of aid officials met overnight in Sumatra to plan a course of action after daylight breaks in the region, Egeland said.
In Washington, State Department spokesman Adam Ereli said the United States is moving into "battle mode" in the wake of the quake, alerting all the U.S. posts in the region and reaching out to aid workers. (Full story)
There was a report of heavy damage on Simeulue Island in Indonesia, said Bernd Schell, head of tsunami operations for the International Federation of Red Cross and Red Crescent Societies.
Speaking from southern Aceh, Schell said "heavy, heavy shaking" lasted about three minutes.
Based on the size of the earthquake, the National Oceanic and Atmospheric Administration initially urged residents within 1,000 kilometers (620 miles) of the epicenter to evacuate coastal regions.
But no tsunamis were reported along Indonesia's island coasts, while India, Malaysia and Thailand canceled tsunami warnings early Tuesday.
The quake's magnitude was variously reported by monitoring agencies as 8.7 and 8.5. The U.S. Geological Survey reported the former after initially putting the magnitude at 8.2; the Pacific Tsunami Warning Center reported the latter.
In the following hours, a series of smaller earthquakes -- one a magnitude 6.7 -- struck the region, the USGS said.
The main jolt was located near the coast of northern Sumatra, about 200 kilometers (125 miles) west northwest of Sibolga, and about 1,400 kilometers (880 miles) northwest of Jakarta, Indonesia's capital. The U.S. Geological Survey said the quake was 30 kilometers (20 miles) deep.
The quake struck at 11:09 p.m. (04.09 p.m. GMT, 11:09 a.m. ET). It was felt in Indonesia, Malaysia, Singapore and as far north as Bangkok, Thailand.
A 'great' quake
The quake was centered on the same fault line where the December 26 earthquake launched a tsunami that left more than 300,000 people dead or still listed as missing. (Full story)
The December 26 quake was a magnitude 9.0 -- the strongest in 40 years. It triggered a massive tsunami that devastated coastlines in nearly a dozen nations in Africa and Asia.
"This looks like a fraternal twin of the December 26 earthquake," said Kerry Sieh, a professor of geology at the California Institute of Technology.
"It's not a duplicate. It occurred a little bit further south," Sieh said. "But it's the same type of earthquake."
Only 12 great earthquakes have occurred since 1906, he said.
The quake is considered a "great" earthquake, the largest of seven grades. The grades are very minor, minor, light, moderate, strong, major and great.
The absence of an early warning system in the Indian Ocean has been decried as contributing to many deaths in December's disaster.
"This time, at least, people heard about the earthquake," Egeland said. "Many people fled inland."
Spared another tsunami
It was not immediately clear why the region was spared another tsunami. Experts agreed the magnitude of the earthquake was sufficient to create one.
"At this point in time we don't know what type of fault occurred ... and that is critical information," USGS spokesman Doug Blake said. "It is in the aftershock zone of the December 26 quake. It's a little bit south, but it's on the same fault."
A 9.0 earthquake would release about double the amount of energy as an 8.7 quake, said a USGS geologist.
The quake may have sent its energy farther south than last year's quake, said Robert Cessaro of the Pacific Tsunami Warning Center.
"So all that pressure to the north would have been relieved" by the December quake, said Cessaro. "We think this event probably ruptured to the south, with the beam of energy probably propagated to the south."
Few land masses lie to the south, but among them are the Cocos Islands, located about 2,500 kilometers (1,550 miles) north-west of the West Australian capital of Perth.
About three hours after the quake, a "small" tsunami was measured on the Cocos tide gauge, the USGS said.
The Australian Bureau of Meteorology confirmed that a wave of 25 centimeters passed the Cocos Islands, compared with the 33-centimeter wave recorded after the December 26 earthquake.
In Thailand, thousands of people in the six provinces affected by the December 26 tsunami moved to higher ground or 2 kilometers (1.25 miles) inland, the governor of Phang Nga province said.
Prass Prawoto, an aid worker in Banda Aceh, which was severely damaged by the December tsunami and quake, said Indonesians moved to higher ground, fearing another massive tsunami. But he said he had not heard of any injuries.
CNN producer Kathy Quiano, watching television reports from Jakarta, said there was widespread panic in Banda Aceh, as residents rushed inland. Electricity and phone service were out in major sections of the city.
A number of traffic accidents occurred as a result, and people were injured, she said, citing local television reports.
CNN's Naurant Prapanya contributed to this report.
'''March 28, 2005'''
Epicenter map from NOAA
A magnitude 8.7 earthquake has been reported in northern Sumatra, Indonesia by the U.S. Geological Survey (originally an 8.2 magnitude at 2:37 ET (7:37 GMT) the USGS reclassified it to an 8.7 magnitude). 
Government spokesman Agus Mendrova reported more than 290 deaths on the island of Nias. Hundreds of others were reported trapped in collapsed buildings, including structures weakened by the December 26th earthquake.

A destructive wave was intially feared and many nations issued tsunami warnings. After the quake a USGS instrument near the Cocos Islands recorded a tsunami type wave which the USGS classified as "small." Tsunami warnings were later withdrawn.

The quake occurred at 11:09 ET (16:09 GMT), and is considered a "great" earthquake, the largest of seven grades. This earthquake is also classified as a "shallow" earthquake, occurring within the top 50 kilometres of the Earth's crust. Shallow earthquakes are more likely to cause a tsunami, because as the lower within the surface the earthquake occurs, the less warping of the ocean floor occurs.  This earthquake was a thrust quake; the December 26th Indian Ocean quake was considered a megathrust quake.

The U.S. Geological Survey originally estimated the magnitude at 8.2, but Japan's Meteorological Agency measured the quake at magnitude 8.5 and the U.S. Geological Survey later raised its estimate to 8.7.  In comparison, last December's earthquake was measured at 8.1 initially by the USGS, before finally being placed within the 9.1 to 9.3 range by scientists in February 2005. 

At 16:29 UTC, an informational Tsunami Bulletin Number 001 was released by the Pacific Tsunami Warning Center, stating that there is no threat to Pacific coastlines, but warning of the possibility of destructive tsunamis on waters near the earthquake's origin.

There have been numerous reports of persons who have felt the earthquake fleeing their homes to higher ground, and Sri Lanka was under an evacuation order. Residents of Banda Aceh, Indonesia, one of the cities most devastated by the December tsunami, also fled. Since the December 26th earthquake relatively minor tremors have been common however this was reported to be more intense and long-lasting than any aftershock.

Thailand, which was criticized for its failure to alert citizens to tsunami dangers after last December's earthquake, warned about the possibility that a tsunami might hit that nation's southern provinces.