Why aren't earthquake warnings better? 01:38
Story highlights
- Tsunami warnings have been lifted for Indonesia; no signs so far of casualties or damage
- The earthquake struck 15 miles deep and about 500 miles from Sumatra, Indonesia's largest island
- Large earthquakes are relatively common around Indonesia, which is part of the Ring of Fire
(CNN)A
magnitude-7.8 earthquake struck Wednesday off the coast of Indonesia,
another major tremor in an area known for those -- though, thankfully,
this one didn't immediately appear to cause widespread death or
destruction.
The quake
was centered in the Indian Ocean about 410 miles (660 kilometers)
southwest of Muara Siberut and roughly 500 miles west-southwest of
Padang, which is on the west coast of Sumatra, the Asian archipelago
nation's largest island.
The U.S. Geological Survey indicated the earthquake struck 15 miles deep.
After
initially noting a "potential ... threat," the Pacific Tsunami Warning
Center, a U.S. government agency, said there had been "no tsunami
observed."
Just in case, Australia's Bureau of Meteorology
issued warnings for Cocos Island, which is about 530 miles
south-southeast of the quake's epicenter, and Christmas Island. A watch
once in effect for Australia's west coast was canceled.
Both
Australian warnings noted the possibility of "dangerous rips, waves and
strong ocean currents," as well as localized onshore flooding, for
several hours Wednesday night.
CNN Map
M7.8 earthquake
Indonesia's disaster management agency reported that tsunami warning sirens went off after the quake, which was felt in Padang.
Authorities
were still trying to contact disaster agencies late Wednesday on
Mentawai, which includes Muara Siberut. But there are no reports of
casualties or damage, nor have there been signs of possible tsunamis on
the islands of Sumatra, West Sumatra, Bengkulu and Lampung.
And all tsunami warnings for Indonesia had been lifted as of 10:50 p.m. (10:50 a.m. ET) Wednesday.
Indonesia in Ring of Fire
Large
earthquakes are relatively common in and around Indonesia, which is
part of the Ring of Fire, an arc of fault lines circling the Pacific
Basin that is prone to frequent earthquakes and volcanic eruptions.
Two earthquakes, one a magnitude 7.1 and the other a 7.0, struck in November 2014.
More recently, on February 12 of this year, a magnitude-6.5 earthquake struck the Indonesian island of Pulau Sumba.
Neither of those did significant damage, though that's not always the case.
In December 2004, a magnitude-9.1 quake struck off the west coast of Northern Sumatra and the tsunamis it generated killed upwards of 225,000 people in India, Sri Lanka, Indonesia, Thailand, Malaysia, Somalia,
Kenya, Tanzania and Bangladesh. That quake, which lasted between 500
and 600 seconds, released an amount of energy equal to a 100-gigaton
bomb.
More than 1,300 people were killed three months later following an 8.7 earthquake and subsequent tsunami
on the same fault line. Another quake, this one a 6.3, killed some
5,750 people in May 2006, and there have been a number of other deadly
incidents since.
Fast facts: Earthquakes