Posted on 03/17/2005 8:56:24 AM PST by TigerLikesRooster
By ANDREW C. REVKIN
Published: March 17, 2005
The violent thrust of the seabed near Sumatra, Indonesia, that touched off catastrophic tsunamis in December created significant new risks of earthquakes and tsunamis there, seismologists are reporting today.
The researchers say that the place at greatest risk from a new earthquake is the devastated city of Banda Aceh and that the tsunami risk lies along Sumatra's heavily populated southern coasts. But they added that any fresh tremors or waves would be unlikely to have anywhere near the destructive power of the December earthquake, the world's second most powerful seismic shock in 100 years.
Still, the researchers, from the University of Ulster in Northern Ireland, said the new threat added urgency to efforts to extend the world's only existing tsunami-warning network, in the Pacific, to include the Indian Ocean.
They said they could not predict when the next shocks might occur, but noted that in similar geological settings, in Turkey and Japan, big quakes had set off tremors in adjacent faults in a few months or years.
The findings are described in the journal Nature.
Ross S. Stein, a seismologist with the United States Geological Survey in Menlo Park, Calif., who was not involved in the new study but developed a method the authors used to calculate risks, called the analysis "important and sobering."
"What we need now are networks of seismometers in Sumatra and its offshore islands," he said. "If the rate of small shocks climbs, I would become very worried about the prospects of a successive shock."
The Ulster researchers pinpointed the risks by mapping patterns of aftershocks and using a computer simulation to determine where the quake had intensified or relaxed stresses on nearby seams in earth's crust.
Beneath Banda Aceh, the tectonic shifts in December appear to have loosened two vast rock faces pressing together along 180 miles of the Sumatra Fault, which bisects the island. The change makes it more likely that one side could slip abruptly past the other and cause a destructive horizontal jolt, said Prof. John McCloskey, the lead author of the study.
Elsewhere the Sumatra Fault has produced major earthquakes, but the northern section, where the pressures have changed, has not seen a big earthquake in more than 100 years, he said. That means it is probably experiencing pent-up stress.
The other quake-prone fault lies in the Sunda Trench, a deep scar in the sea bottom running southeast from the epicenter of the December earthquake, the team said. An earthquake there could generate deadly waves, as previous quakes did at least twice before, in 1833 and 1861.
Recent computer simulations recreating the 19th-century upheavals and waves suggest that tsunamis from the Sunda Trench would pose a grave risk to Sumatra's southern shores but would not sweep other South Asian coasts.
The most imminent risk, Dr. McCloskey said, is probably in the fault beneath Banda Aceh.
Better there than here.
Oh, we've got plenty of stuff primed to go, too.
This wouldn't be happening if John Kerry had been elected.
Well, you don't live in California, do you?
I saw on one news site the title (or the effect of): Tsunamis Created Greater Chance of New Earthquakes!!!
Like the tsunamis themselves caused the plates to move.
Not just CA..Utah, etc.
St. Louis/New Madrid.
Yeah really. I am reading a book now called the Rift which is a possible scenario of the New Madrid fault goes. Not pretty.
Actually slightly overhyped I suspect (not that there isn't a danger of a Mag 6-7 quake somewhere in the area in the next 40 years) relative to other areas with more risk, like Salt Lake City.
Went to the guy's website and saw this:
"They won't stop barking. And then the earth shrugs-- 8.9 on the Richter scale. It's the world's biggest earthquake in over two thousand years"
Unfortunately, the above reveals the author of "The Rift" to be a moron. Even before the Sumatran quake there had been multiple quakes larger than 8.9 in just the last 100 years.
I'd take ANYTHING about geology or seismology in the book with a massive boulder of salt.
Yep...Mid-Atlantic ridge & plenty of old faults for the East coast....Volcanoes and faults for the West coast....
True. In fact, I believe the last time the New Madrid went in 1811 and 1812 there were 3 quakes that were all over 9. Not to mention that Alaska has 9's every now and then. I just can't even imagine being in a quake that strong. I sure don't ever want to see one. The book is actually a good read though, in spite of not being letter perfect in volcanology.
Just like everything else, it's Bush's fault!
I wonder how much of a Wasatch Fault quake Glen Canyon Dam and Hoover Dam can survive.
"I saw on one news site the title (or the effect of): Tsunamis Created Greater Chance of New Earthquakes!!!
Like the tsunamis themselves caused the plates to move."
You expect newsreporters to be educated? Journalism is the college department for those who cannot think, only espouse.
This is the article I saw.
http://washingtontimes.com/upi-breaking/20050316-045609
WASHINGTON, March 16 (UPI) -- U.S. scientists said there is a high potential for devastating tsunamis in the Caribbean region, based on historical data since the arrival of Columbus.
Scientists at the University of North Carolina and the University of Texas said movement of tectonic plates north of the Island of Hispaniola could trigger giant tsunamis, with effects felt in the Greater and Lesser Antilles and along the U.S. East and Gulf coasts. In all, some 35.5 million people are now at risk should a strong tsunami hit the northern Caribbean.
Since 1492, the plate movement has generated at least 10 significant tsunamis in the northern Caribbean, the scientists said. Six of the events resulted in loss of life and all 10 were triggered by movement along the plate boundary, which extends some 2,000 miles (3,200 kilometers) from Central America to the Lesser Antilles.
The most recent of the destructive northern Caribbean tsunami occurred in 1946 and was triggered by a magnitude 8.1 earthquake in the Dominican Republic. It killed around 1,800 people.
Dramatic 3D images of the ocean bed where a monstrous earthquake caused the Asian tsunami have been captured by a UK Royal Navy ship.
The sonar image reveals ridges 1500 metres tall and a massive trench (Image: Royal Navy)
The images reveal a landscape transformed by the quake which occurred as the Indian tectonic plate pushed against the Burma plate - its leading edge being driven further beneath it.
The earthquake - now thought to have measured a colossal 9.3 on the Richter scale - displaced massive amounts of water and produced killer waves that sped to coastlines around the Indian Ocean on 26 December 2004.
The map of the ocean floor was captured using high-resolution multi-beam sonar from a UK Royal Navy survey ship, the HMS Scott. Marine geologists aboard the ship identified features that bear testament to the earthquake that wrenched the ocean bed, including slabs of rock dragged up to 10 kilometres along the seabed by the force of the displaced water. The images also show mountainous ridges 1500 metres tall and an oceanic trench several kilometres wide, created over much greater periods of time by activity along the fault.
Researchers from the Southampton Oceanography Centre, UK, and the British Geological Survey are analysing the pictures aboard the ship. The images should help scientists understand the geological process that produced the tsunami and ultimately assist with the construction of an early warning system for the Indian Ocean.
"From this we hope to better understand the geological processes which produced the earthquake and ultimately help to determine future earthquake and tsunami hazards so that everyone can be aware and prepared," said Lisa McNeill, of the Southampton Oceanography Centre.
That trench is massive!
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