Sumatran Earthquakes Felt in Singapore

There have been two recent earthquakes on the western side of the island of Sumatra (Indonesia) in the past two days, and I've gotten one e-mail from a relative so far asking me how I'm doing. The earthquakes by themselves were much too distant to have caused any damage here in Singapore, and we are on the wrong side of Sumatra to have been affected by the tsunami (apparently there was a small one that reached about one meter - that's three feet for you Americans ;) - in height).

However, tremors were felt here both last night and this morning. My sister-in-law called us up last night asking if we had felt it (she had). That tremor happened at 6:10 pm. Milady and I were on our way home at the time and, thus, being on the ground, didn't feel it. (Whereas my sister-in-law was probably at home at the time; her flat is fairly high up and apparently her building swayed a bit. Had we been home, which is about as high up as my sister-in-law's flat, we might have also felt the tremor.)

The second tremor was felt this morning some time between 7:45 and 8:00 am. Although there were some reports from my neighborhood of residents feeling this morning's tremor, I did not feel it, even though I was at home.

Below are some excerpts from a few news reports on the earthquakes:

Another quake hits Sumatra at 7:21 p.m.

JAKARTA (JP): A second earthquake hit West Sumatra on Wednesday evening, just one hour after a powerful quake struck its neighboring province of Bengkulu at 6:10 p.m.

The second earthquake, with a magnitude of 5.7 on the Richter scale, was centered 154 kilometers southwest of Painan, West Sumatra, at a depth of 66 kilometers, the Meteorology and Geophysics Agency reported on its website. (Source)

Death toll in western Indonesia earthquake rises to six

JAKARTA (JP): The powerful earthquake that hit Bengkulu on Wednesday evening killed five people and injured at least 20 others in the province, Metro TV reported Thursday.The TV station also reported the 7.9 magnitude quake killed a man in Padang, West Sumatra, and injured two.The earthquake, which occurred at 6:10 p.m., damaged hundreds of buildings in the region, including a governor's office and hospitals. (Source)

Plate movement, awareness may have cut Indonesian toll: expert

JAKARTA (AFP) — The direction of plate movements that sparked quakes off Indonesia's Sumatra spared the coast from damaging tsunamis, while geology and awareness may have reduced the damage, an expert said Thursday.

"Most probably the quakes were caused by horizontal shifts in the continental plates," said Subardjo, a seismology expert with the Indonesian meteorological agency.

"So although similar amounts of energy were released, it had a different effect than when the quakes are caused by vertical shifts of the plates."

It was a vertical shift that caused the massive quake that unleashed the 2004 Indian Ocean tsunami, which killed 168,000 people in Aceh province at the tip of Sumatra and more than 50,000 others in the region.

"It appears that this didn't happen in the recent string of quakes in Bengkulu," Subardjo told AFP.

Authorities here automatically issue tsunami warnings for shallow underwater quakes at magnitudes higher than 6.3.

Land damage on the other hand may have been limited by the geology specific to the areas near the epicentre, including Bengkulu, a city of about 300,000 people, he said.

Bengkulu was also hit by a 7.3-magnitude quake in June 2000, which killed about 88 people and injured nearly 1,000 people seriously.

"Maybe buildings were rebuilt to withstand tremors better after that, and people are more aware of quakes as well," Subardjo said.

Rahmat Priyono, another seismologist from the agency, said that the series of quakes rocking the coast are being considered part of the same string of events.

"The strong quakes were mostly centred in the ocean, although we recorded at least one with a 6.1-magnitude on land, and this was potentially more damaging on the ground," he said.

The initial quake was measured by the agency at 7.9-magnitude, with the numerous aftershocks, including one clocking in at 7.7, considered to be a ripple effect after the first massive release of energy, he said.

The US Geological Survey gradually upgraded the strength of the first quake from 7.9 to 8.2 to 8.4.

Any quake over 7.0 is considered strong enough to cause massive destruction and heavy loss of life. (Source)

Strong quake hits Indonesia; tremor felt in Singapore

SINGAPORE: Tremors were reported in several parts of Singapore at about 8am on Thursday.

Police and the Singapore Civil Defence Force (SCDF) received about 500 calls from the public about the tremors.

The National Environment Agency said an 8.3-magnitude earthquake occurred at about 7:45 this morning in southern Sumatra, approximately 600km from Singapore.

Police said 248 buildings experienced tremors, and the affected building were located mainly in Clementi, Jurong, Toa Payoh, Punggol, Hougang, Woodlands and Central Business District areas. (Source)

Another powerful quake shakes Indonesia

PADANG, Indonesia - The second powerful earthquake in as many days shook western Indonesia Thursday, collapsing buildings in a coastal city and triggering tsunami alerts around the region. The latest quake was also felt in Malaysia and in Singapore where tall buildings swayed. It triggered at least one strong aftershock.

On Wednesday, a strong earthquake shook Southeast Asia, collapsing buildings, killing at least five people and injuring dozens in Indonesia. That tremor triggered a small non-destructive tsunami off the coastal city of Padang on Sumatra, the Indonesian island ravaged by the 2004 tsunami disaster. A tsunami warning was issued for wide areas of the region and nations as far away as Africa.

Thursday's magnitude-7.8 quake rattled the same area of Sumatra.

Rafael Abreu, a geologist with The U.S. Geological Survey in Colorado, said the quake on Thursday did not appear to be an aftershock to the 8.4-magnitude temblor the day before. But the centers of both were close together.

"We are not calling it an aftershock at this point. It's fairly large itself. It seems to be a different earthquake," Abreu said.

"The quake seems to be pretty shallow," he said. "These are the quakes that can produce tsunamis."

Indonesia issued a tsunami warning, lifted it and then reissued it. A tsunami watch was also in effect for Australia.

The USGS said the new quake was centered about 125 miles from Bengkulu, a city on Sumatra. It occurred at a shallow depth of about six miles and struck at 6:49 a.m.

...

Suhardjono, a senior official with the local meteorological agency who like most Indonesians uses only one name, said a small tsunami, perhaps 3-feet high, struck Padang about 20 minutes after the quake. The Pacific Tsunami Warning Center also reported a small wave.

But most of the damage appeared to come from the ground shaking.

...

The undersea temblor hit around 6:10 p.m. at a depth of 18 miles, the U.S. Geological Survey said. (Source)