More powerful than Kashmir earthquake couldstrike soon, scientists predict

More powerful than Kashmir earthquake could
strike soon, scientists predict
For Indian seismologists it has never been a
question of whether but when. Ever since the
sub-sea Sumatran quake that triggered a
tsunami in December 2004, they have warned
that the Indian plate has become "seismically
very active" and needs close tracking.
The Indian plate is one of the 14 major plates
that are locked on to the surface of the earth
like a jigsaw puzzle. And when these rigid
plates nudge one another, the accumulated
stress which is built up along the boundaries is
released to trigger an earthquake.
They may be adept at explaining how and why
earthquake happens, but seismologists, even
after decades of painstaking study, are still in
the dark about when or where exactly it will
strike or how severe it will be.
What they know for sure is that the frequency
of earthquakes along the Indian plate has
increased and this trend could continue.
At times scientists stick their neck out to
forewarn-like they did after the tsunami-about
abnormal seismic activity in north-east India
and the Himalayan region.
However, in a study published in the journal
Science in 2001, specialists from the University
of Colorado, US, and the Indian Institute of
Astrophysics in Bangalore, who studied seismic
data in the Himalayan region, concluded that a
major earthquake was overdue.
They estimated that two major quakes, with a
magnitude of 8.1-8.3, could strike at any
moment. Worse, the big ones coming are
expected to cause havoc in highly populated
areas in the subcontinent, putting an estimated
five crore people at risk. Among the cities in the
line of threat are Delhi, Kolkata, Lucknow,
Islamabad, Kathmandu, Dhakha and Thimphu.
The October 8 earthquake lies along the fault
line where the Indian and the Eurasian tectonic
plates collide, pushing up the Himalayan
mountain range. The Indian plate drives
northwards at a rate of a few centimetres every
year, moving under the Eurasian plate and
creating a zone that is prone to seismic
activity. To that extent, the Kashmir earthquake
fitted in with the scientists' predictions. But
thankfully, it was relatively weak.
"The effects of the earthquake were lessened
because it emerged 10 km below the earth's
surface," says seismologist Janardhan G. Negi,
director-general, Madhya Pradesh Council for
Science and Technology. However, aftershocks
could trouble the area for a few more months.
American geologists Roger Bilham and Kali
Wallace of the University of Colorado point out
that the Himalayan region-from the eastern
Indian plate boundary in Myanmar to the
western boundary through Pakistan and
Afghanistan-has a dozen regions that could
experience a future earthquake with a
magnitude more than 8. Since the population of
the Ganga basin is greater than at any time in
history, they say that any massive earthquake
in the future could affect people more than last
year's tsunami did.
Generally, Indian geologists are restrained when
it comes to issuing a caution or an earthquake
warning. The exception is a 10-member group
led by Harsh K. Gupta, former director of the
National Geophysical Research Institute,
Hyderabad, which has alerted that an
earthquake with a magnitude of 5 could hit
Koyna in Maharashtra in the next few weeks.
Privately though, some of them are
apprehensive about a big one striking in the
region between Himachal Pradesh and Assam in
the next 10 years. But they do not rule out
smaller ones.
As the number of people displaced by the
Kashmir quake rises to 25 lakh, seismologists
are also concerned about the construction of
buildings. In Kashmir, most buildings were too
weak to withstand earthquakes. In the absence
of accurate predictions regarding quakes, the
only option for urban India, where construction
continues to be haphazard, is to ensure that
structures are built to resist substantial
tremors.
In metros and elsewhere, old buildings made of
brick and mortar, could cave in if there is a
serious quake. Architects point out that
reinforced concrete filled in with brickwork
provides very little resistance to lateral forces
like those triggered by a quake. It is only the
use of better quality steel and a strict
adherence to safety regulations based on the
study of soil that can prevent a collapse.