[list_indonesia] [ppiindia] New Asian quake threat warning
- From: "Ambon" <sea@xxxxxxxxxx>
- To: <"Undisclosed-Recipient:;"@freelists.org>
- Date: Thu, 17 Mar 2005 09:36:40 +0100
** Mailing-List Indonesia Nasional Milis PPI-India www.ppi-india.da.ru **
http://news.bbc.co.uk/2/hi/science/nature/4354217.stm
Last Updated: Wednesday, 16 March, 2005, 18:22 GMT
New Asian quake threat warning
By Paul Rincon
BBC News science reporter
The quake occurred at the boundary of the Indian and
Burma plates
A build-up of stress on faults in Sumatra following the
Indonesian earthquake is likely to trigger another large quake and perhaps a
tsunami.
That is the claim made in Nature by a team from the
University of Ulster, UK.
The slip that caused last year's devastating quake placed
increased stress on the Sumatran fault and on the adjacent undersea Sunda
Trench.
A new rupture could trigger a magnitude 7-7.5 quake on land
and a magnitude 8-8.5 quake beneath the sea, they say.
I am comfortable talking about a significant increase
in the risk of another quake
John McCloskey, University of Ulster
The 2004 earthquake occurred when the deep, flat Indian plate
slipped under the Burma plate.
Major earthquakes tend to cluster in these subduction zones
where two or more plates of the Earth's crust grind and overlap.
When a quake takes place, the displacement causes the
surrounding crust to become distorted. This places stress on other fault lines
and structures in the area.
Researchers from the University of Ulster at Coleraine used
information about displacement following December's magnitude 9.0 quake to
calculate the stresses it placed on the surrounding region.
Stress zone
They concentrated on the Sumatran fault, a so-called
"strike-slip" fault which cuts through the island of Sumatra, and the Sunda
trench, a continuation of the underwater subduction zone that ruptured to cause
the tsunami last year.
"We found that both of them had been significantly loaded, in
stress terms, by the 26 December quake," said lead author John McCloskey.
Satellite images revealed the tsunami's raw power.
(Image: Digital Globe)
Their results show a stress increase of up to five bars in
the 50km stretch of the Sunda trench located next to the rupture zone. They
show an increase of up to nine bars for about 300km on the Sumatra fault near
the city of Banda Aceh.
Based on these findings, the scientists predict a possible
magnitude 7-7.5 earthquake on the Sumatran fault and a magnitude 8-8.5 quake at
the Sunda trench.
"The huge changes in stress mean that I am comfortable
talking about a significant increase in the risk of another quake. But that is
as far as I am prepared to go," Professor McCloskey told the BBC News website.
The researchers stop short of predicting when another large
quake will strike the region. But similar events elsewhere in the world have
occurred within a few years of each other, or even a few months.
Another tsunami?
In Japan, at least five major quakes in the Nankaido segment
of the Nankai subduction zone have been accompanied by similar events on the
linked Toanakai/Tokai segment within five years - and three of the subsequent
quakes ruptured in the same years as their precursors.
The magnitude 7.4 Izmit earthquake in Turkey in 1999
triggered the magnitude 7.1 Duzce earthquake three months later.
Some researchers believe large earthquakes occur at the Sunda
trench on a cycle of 200 years, which is determined by stress loading at the
subduction zone. The last big event occurred 150 years ago, but Professor
McCloskey said the recent quake could have accelerated this cycle.
"The amount of extra stress could be equivalent to 50 or 60
years of loading. But I personally am not convinced by this theory," he said.
A large earthquake at the undersea Sunda trench had the
potential to cause another tsunami, the University of Ulster researcher added.
But Professor Nick Ambraseys of Imperial College London, UK,
warned against making predictions that could cause panic, when there was no way
to tell when another earthquake would occur.
"False alarms and inaccurate timing could create more
problems than already exist," he said.
"There is nothing in their article that enables, with any
degree of certainty, the prediction of the immediacy of the next earthquake."
The authors of the report say this makes a tsunami early
warning system for the Indian Ocean all the more urgent.
[Non-text portions of this message have been removed]
------------------------ Yahoo! Groups Sponsor --------------------~-->
Give underprivileged students the materials they need to learn.
Bring education to life by funding a specific classroom project.
http://us.click.yahoo.com/4F6XtA/_WnJAA/E2hLAA/BRUplB/TM
--------------------------------------------------------------------~->
***************************************************************************
Berdikusi dg Santun & Elegan, dg Semangat Persahabatan. Menuju Indonesia yg
Lebih Baik, in Commonality & Shared Destiny. www.ppi-india.uni.cc
***************************************************************************
__________________________________________________________________________
Mohon Perhatian:
1. Harap tdk. memposting/reply yg menyinggung SARA (kecuali sbg otokritik)
2. Pesan yg akan direply harap dihapus, kecuali yg akan dikomentari.
3. Lihat arsip sebelumnya, www.ppi-india.da.ru;
4. Satu email perhari: ppiindia-digest@xxxxxxxxxxxxxxx
5. No-email/web only: ppiindia-nomail@xxxxxxxxxxxxxxx
6. kembali menerima email: ppiindia-normal@xxxxxxxxxxxxxxx
Yahoo! Groups Links
<*> To visit your group on the web, go to:
http://groups.yahoo.com/group/ppiindia/
<*> To unsubscribe from this group, send an email to:
ppiindia-unsubscribe@xxxxxxxxxxxxxxx
<*> Your use of Yahoo! Groups is subject to:
http://docs.yahoo.com/info/terms/
** Mailing-List Indonesia Nasional Milis PPI-India www.ppi-india.uni.cc **
Other related posts:
- » [list_indonesia] [ppiindia] New Asian quake threat warning
