Magnitude 8.0 quake hits Sumatra
Wed Sep 12, 2007 12:40PM BSTJAKARTA (Reuters) – An earthquake measuring 8.0 struck Indonesia’s Sumatra region on Wednesday, the United States Geological Survey said.The quake had the potential to cause a tsunami, an Indonesian meteorological agency official said, putting the magnitude at 7.9.Some offices in Jakarta were evacuated after the tremors were felt. Witnesses in Singapore and Thailand said they also felt the quake.http://uk.reuters.com/article/topNews/idUKSP24372520070912Powerful Quake Hits Indonesia 41 minutes ago JAKARTA, Indonesia (AP) — A powerful earthquake hit Indonesia on Wednesday, causing buildings to sway strongly in the capital, and authorities issued a tsunami warning for much of the Indian Ocean region.The U.S. Geological Survey said the quake had a preliminary magnitude of 7.9 and hit at about 6:10 p.m. (7:10 a.m. EDT). It was centered 9.7 miles underground in the southern Sumatra area, the USGS said.The Pacific Tsunami Warning Center issued a tsunami warning for wide areas of the region.“Earthquakes of this size have the potential to generate a widespread destructive tsunami that can affect coastlines across the entire Indian Ocean Basin,” it said.In Jakarta, tall buildings swayed for several minutes, and occupants rushed down the stairs to escape.Indonesia, the world’s largest archipelago, is prone to seismic upheaval due to its location on the so-called Pacific “Ring of Fire,” an arc of volcanos and fault lines encircling the Pacific Basin.In December 2004, a massive earthquake struck off Sumatra island and triggered a tsunami that killed more than 230,000 people in a dozen countries, including 160,000 people in Indonesia’s westernmost province of Aceh. http://ap.google.com/article/ALeqM5hzfwhj9j9AitFP4tJVs2atvGjbbA Earthquake jolts eastern Indonesia12:45, September 12, 2007 (Peoples Daily online)An earthquake with magnitude of 5.0 struck easternmost of Indonesia on Wednesday, with no report of casualty or damages, Meteorology and Geophysics Agency said.The quake rocked at 08:55 Jakarta time (0155 GMT) with epicentre at 607 kilometres northeast Jayapura of Papua province and at 48 kilometres in depth, an official of the agency said.
Indonesia is laid on a vulnerable quake-hit zone so called “the Pacific Ring of Fire,” where two continental plates meet that cause frequent seismic and volcanic movements.
Source: XinhuaPowerful earthquake hits Indonesia, tsunami warning issued Jakarta, Sept. 12 (AP): A powerful earthquake hit Indonesia today, causing buildings to sway strongly in the capital, and authorities issued a tsunami warning for much of the Indian Ocean region. The US Geological Survey said the quake had a preliminary magnitude of 7.9 and hit at about 6:10 p.m. (1640 IST). It was centered about 15.6 kilometers underground in the southern Sumatra area, it said. The Pacific Tsunami Warning Center issued a tsunami warning for wide areas of the region. “Earthquakes of this size have the potential to generate a widespread destructive tsunami that can affect coastlines across the entire Indian Ocean Basin,” it said. In Jakarta, tall buildings swayed for several minutes, and occupants rushed down the stairs to escape. http://www.hindu.com/thehindu/holnus/000200709121712.htm
The bathymetrymap of the project area and segments of dredging work are indicated in the attached jpg. It may be seen that Segment A-G is south of Rama Setu; segment A-B cuts through Rama Setu and Segment B-C is north of Rama Setu. All these segments together constitute the geophysical feature on top of which the physical structure exists. Any dredging or project work in ALL these segments from base to base of the ridge constitutes what is called ‘Adam’s Bridge’ work segment in the detailed project report. The injunction of SC should apply to this Adam’s Bridge work segment. It is now a clever strategy adopted by the corporation to invent a new phrase called ‘North of Adam’s Bridge’ a phrase which was never used before on the govt. website. This is clearly intended to cover their contempt of court and continuing work on Rama Setu segment. Any work on any of the mentioned segments will impact on the physical structure, the world heritage monument, Rama Setu. Scientists also have said any project work is likely to trigger the fault lines and the heat-flow zone resulting in incalculable damage to the coast and the aquatic resources. Gulf of Mannar is one indivisible water body which impacts both the coast of Bharatam and the coast of Srilanka. The temporary injunction given upto 14 Sept. has to be made absolute until scientists investigate and report on impact on thorium wealth, on impact of impending tsunami reported in the prestigious Nature magazine of 6 Sept. 2007, a tsunami expected to be more devastating than the tsunami of 26 Dec. 2007, a tsunami which is estimated to put 60 to 70 million people of the Bay of Bengal at risk. That the tsunami effects and tsunami protection measures are NOT part of the project call the stability of the project to question and continuing the project work in Rama Setu area will create a national security issue, security of the coastline. In fact, the Govts should be called upon to examine the tsunami warning report and suspend all project works in the eastern and southern coasts pending review by multi-disciplinary teams of the protective measures and warning systems to be put in place to cope with the impending tsunami
Published online: 5 September 2007; | doi:10.1038/news070903-10 (News@nature.com)
New tsunami warning
60 million people in the Bay of Bengal may be at risk.
The modelled height of a tsunami that likely hit in 1762(red = 2.5m).
The densely-populated Bay of Bengal looks to be at risk from very large tsunami-producing earthquakes, according to a new analysis of modern and historical observations.
Phil Cummins, a seismologist at the national Geoscience Australia agency in Canberra, who publishes the analysis today in Nature1, is quick to say that his ideas need confirmation before “policymakers start doing anything”. But with the 2004 Indian Ocean tsunami fresh in everyone’s mind, his conclusions are likely to raise the hairs on the back of a few necks.
The northern Bay of Bengal was formerly thought to be an unlikely place for the large earthquakes that result when tectonic plates that are pushing against one another suddenly wrench, with one plate slipping below the other. These ‘megathrust’ earthquakes can cause tsunamis, as water is suddenly displaced up and down by the thrusting rock. The plate boundary further south, off the coast of Sumatra, causes such quakes — one of which created the devastating 2004 wave.
Previous research has hinted that, further north, the plate boundary comes ashore in Myanmar rather than continuing up into the northern end of the Bay of Bengal, that the Indian Ocean plate is not subducting there, and that the land beneath Burma is instead moving north with the Indian continental plate. But the seismological and geological evidence for this is complex and open to interpretation.
Cummins favours the interpretation that that the plate boundary is actually some 100-200 kilometres further west. This puts it underwater, where it has the potential to create waves during a quake. He also argues that there is convincing evidence that the subduction zone is still active here.
If so, there is a 900-kilometre long earthquake-producing line running underwater from the northern tip of the Bay of Bengal towards the Andaman islands. Cummins modelled a quake on the northern part of this zone and found that 60 million people live within 10 metres of sea level in area that would be affected. In a conservative estimate, he concludes that more than a million lives are at risk — although a wave may not strike for hundreds of years.
Kerry Sieh, a seismologist at the California Institute of Technology in Pasadena, who works on the same area, calls the work “a very good advertisement for a problem that is unappreciated in the general community”. While reiterating that the analysis is “open to question”, he thinks Cummins is “probably right”.
There is scant written evidence of previous tsunamis in the area, but Cummins’ hypothesis is supported by the writings of British Captain Edward Halsted, who visited Cheduba Island, off the coast of what is now Myanmar, in 1841.
In between recording the islanders’ habit of keeping their cigars handy in their ear piercings and an account of an interview with an 106-year old inhabitant (of whom he wrote that “not a tooth in his head was gone or apparently inclined to depart”), Halsted recorded the memory of and geological evidence for a very large earthquake with accompanying tsunami in 1762 that “washed to and fro several times with great fury and then retired from the grounds, leaving an immense quantity of fish, the feasting on which is a favourite story throughout the island.”
“These British guys, it is amazing what they were interested in,” says Cummins.
Both Cummins and Sieh suggest that more seismic data should be gathered with fine-resolution global positioning system instruments, and that more physical evidence of previous large earthquakes should be sought to confirm where the plate boundary is, and how it behaves.
Sieh worries that for Bangladesh, the country where perhaps the largest number of people could be affected, even confirmation of Cummins’ ideas is unlikely to spur proper preparations. He has found the government there dispassionate about earthquake or tsunami preparedness, he says. “No matter what we learn, given the current social and political situation, it will have no effect. And if an event occurs there will be half a million or a million people dead.”
Gerard Fryer, a geophysicist at the Pacific Tsunami Warning Center in Ewa Beach, Hawaii, says the Bay of Bengal area is decidedly not prepared for a tsunami. “Everyone is really concentrating on central and southern Sumatra. That’s where the new instruments are going in; that’s where everyone expects the next big earthquake to occur,” he says. “I don’t think the Indian or the Bangladeshi governments are prepared.”
“My initial reaction to the paper was disbelief,” Fryer adds. “But then I saw it was by Phil Cummins, and Phil Cummins essentially predicted the 2004 Sumatran tsunami. So when he talks now, people listen.”http://www.nature.com/news/2007/070903/pf/070903-10_pf.html
Study: Tsunami Could Kill 1M in S. Asia
By MICHAEL CASEY 09.05.07, 4:24 PM ET (AP)
BANGKOK, Thailand –
At least a million people in South Asia’s Bay of Bengal could be swept to their deaths by a tsunami if a giant earthquake hits off the coast of Myanmar, according to a study published Thursday.
But the study’s author, Phil Cummins, said he does not have enough data to say whether such a cataclysmic event would hit parts of Myanmar and Bangladesh in the next few decades or in several hundred years.
“I don’t want to cause a panic. There is no reason anything like this would happen soon,” said Cummins, of Geoscience Australia.
The threat of tsunamis has taken on added urgency in recent years after a massive earthquake off Indonesia’s Sumatra island in December 2004 triggered a tsunami that killed more than 230,000 people and left a half million homeless in a dozen countries.
Cummins’ study, which appears in Thursday’s issue of the journal Nature, is the first time anyone has suggested that an earthquake off the coast of Myanmar could spawn a tsunami “that could have pronounced impact on the Chittagong coast and the Ganges-Bhramaputra delta at the northern tip of the Bay of Bengal,” it said.
The numbers of people at risk from a tsunami, Cummins wrote, may be “over a million” given that the region is home to Bangladesh’s second largest city of Chittagong and there are tens of millions living just above sea level.
Cummins has not presented his findings to the governments of Myanmar and Bangladesh. Officials from Myanmar and Bangladesh could not immediately be reached for comment.
The area Cummins studied is a section of the Sunda Megathrust that stretches all the way from Western Australia to the Himalayas. A rupture of the fault was blamed for the Sumatra earthquake in 2004.
Examining historical records, Cummins found evidence that an earthquake estimated at magnitude 8.5 to 9.0 struck off the western Myanmar coast in April 1762. He said it probably produced a tsunami, citing eyewitness accounts of waves washing over nearby Cheduba Island, submerged coasts near Chittagong and rising river levels as far inland as Dhaka.
He said future quakes and tsunamis were likely, given the historical accounts and more recent surveys of the area which determined a magnitude 8.5 quake would hit the area every 100 years and a 9.0 every 500 years.
“I would hope this spurs further work in confirming these past events,” he said. “It should be possible to answer how big was this event, how often do these events occur and what kind of tsunamis are generated through further geological investigation.”
The reaction to Cummins findings has been mixed, with some tsunami experts saying they shed important light on a section of Sunda Megathrust that has received little attention in the past.
“The main value of the paper is in advertising the danger of the section of the megathrust that no one has worried about,” said California Institute of Technology’s Kerry Sieh, who has used coral records and GPS networks to predict that a big quake and tsunami are likely to hit parts of Sumatra Island in the coming decades.
“His point is well taken. This part of the megathrust has produced a larger earthquake in the past and so it could do so in the future too,” Sieh said. “The effects on the west coast of Myanmar and more importantly Bangladesh would be awful.”
But Costas Synolakis, director of the Tsunami Research Center at the University of Southern California, said the possibly of a tsunami in the area was previously known and questioned whether the fault would rupture to the extent estimated by Cummins.
Synolakis also said in an e-mail interview that the scenario presented by Cummins “could lead to a massive panic south of Chennai (India) and possibly a sense of reassurance in Sri Lanka” where he said the threat of another tsunami was worse.
Warning of tsunami greater than 2004
By Roger Highfield, Science Editor
Last Updated: 6:01pm BST 05/09/2007
Tens of millions of people who live in the Bay of Bengal face the threat of a tsunami as massive as the one that devastated the Sumatran coast in 2004, a leading geologist warns today.
While the Boxing Day 2004 disaster took the scientific community by surprise, killing around a quarter of a million people, one geologist who had sounded the alert about the dangers in the Indian Ocean now says many of the same warning signs exist where tens of millions of people live along the coasts of Myanmar, Bangladesh and West Bengal.
Dr Phil Cummins from Geoscience Australia argues in today’s issue of the journal Nature that one reason the signs have not been picked up is because seismic shifts in the region is being masked by the Bengal Fan, a 12 mile thick undersea layer of sediment shed from the Himalayas and Tibet over millions of years.
Earthquakes occur when stress built up as the tectonic plates slide past each other is released. Geologists had assumed the boundary between the Indo-Australian and Asian plates north of the Andaman Islands was one in which the plates were moving past each other horizontally, and not pushing against one another.
But satellite measurements now suggest the plates are pushing together. If there is a sudden release of stress, the resulting upward thrust of the sea floor in the Bay of Bengal could cause a what Dr Cummins called a “giant tsunami” that would reach the Ganges Delta in a couple of hours, where 60 million people live within 10 metres of sea level.
He added that the earthquake itself could be as big as magnitude 9.0 and cause devastation in the northern tip of the Bay of Bengal. “It is difficult to dispute the evidence,” he said, adding that the earthquake that triggered the 2004 tsunami had, “if anything probably increased the risk” of a quake in the newly identified risk region.
To back his fears, the new analysis shows evidence for vertical movement accompanying earthquakes in the historical evidence. One violent earthquake in the area in 1762 caused uplift and subsidence along a large part of the coast, and may have triggered a tsunami.
That same area is now home to major centres like Dhaka and Kolkata. The Nature report suggests that although a major tsunami may still be as much as 200 years away, it is impossible to be sure and the risk, which is currently hard to quantify, should be taken seriously.
Images showing the tectonic setting of the Bay of Bengal (top) and the effect of the 1797 earthquake (bottom)
Prof Richard Arculus of the Australian National University, Canberra, said the warnings should be taken very seriously. “A few months before the devastating earthquake and accompanying tsunami triggered off northern Sumatra in late 2004, Phil Cummins published a perceptive analysis of historic events of this nature in the region.
“He warned that countries bordering the Indian Ocean, including the northern coast of Australia, were at significant risk, and the lack of a tsunami warning system analogous to that deployed in the Pacific was a serious issue.”
Dr Tom Blenkinsop at James Cook University, Queensland, said that the work is novel and important because “unlike the Indian-Asian plate boundary further south, this is an area that was not considered to be at much risk from earthquakes-driven tsunamis.”
Dr Edward Bryant at the University of Wollongong, New South Wales, said: “Dr Cummins’ estimate of a million deaths due to a tsunami from an earthquake in the northeast Bay of Bengal is not scaremongering.
“It is a realistic hypothesis that unfortunately would dwarf the Boxing Day tsunami of 2004 because there still is no effective tsunami warning system in this region. Even if there were, the short lead time before the arrival of the tsunami would prohibit any widespread evacuation.”
Kevin McCue, director of the Australian Seismological Centre, said: “The message is alarming, perhaps justifiably, given the unexpected disaster that followed the great Sumatran earthquake and tsunami of 2004, a disaster of local, regional and global reach.
“Disaster planners might need more information than is given in the paper, particularly some quantitative measure of uncertainties in the science.”
http://www.deccan.com/chennaichronicle/home/homedetails.asp#Study: Tsunami risk in Bay