Resumo de Himalayas Due For Big One

Himalayas due for big one

Powerful earthquakes-
maginitude 8 or larger-occurred in the Himalayas in
1803,1833,1897,1905 ,1934 and 1950. But in the past half
century, the regin has been relatively quiet,with no
earthquakes anywhere near the magnitude of 7.6 that struck
northern Pakistan on Saturday. That calm may have given a
false sense of security to growing populatins of people
living there. ?Those of us in the business knew we were
overdue,?said Mr.Peter Molnar, a professor of geological
sciences at the University of Colorads Mr.Molnar was co-
author of a2001 article in the journal science that looked
at the history of Himalayan earthquakes and how much
tectonic stress was building up as the Indian subcontinent
crashes into Asia. The Science article warned,?several
lines of evidence show that one or more great earthquakes
may be overdue in a large fractin of the
Himalayas,threating millions of people in that region.?
Steven Wesnousky,director of the Centre for Neotectonic
Studies at the University of Nevada in Reno,said
earthquakes with magnitudes similar to the one on s aturday
culd happen at almost anytime alng any part of the
Himalayas. ?It might nor occur for 10 to 20 years,but if
it occurred tomorrow,it would?nt be a surprise,?he said.
Earthquakes like the one that struck the subcontinent on
Saturday are ?really relatively small compared to the
largest earthquakes that zone is capable of
producing,?Mr.Wesnousky said. ?That the scary part.?The
Indian subcontinent slides northward about 4 centimetres a
year as part of the naturalmovement of the continental
plates. Half of that motion is absorbed farther to the
northin Asia,but the other half uts pressure on the
Himalayan mountains,continually building up strain in the
rocks that form the mountain ridge. Mr.Wesnousky and his
colleagues have found that one or two earthquakes,of
magnitude 8.5 to 9mstruck sometime in the 1400s or 1500s.
He said it was not yet clear whether the faults al broke at
once or whether two different sections broke at different
times to cause two separate earthquakes. For a quake with
the magnitude of the one on Saturday-or of about the same
magnitude that hit Sanfranisco in 1906-the fault slips
perhaps 2.5 to3.5 metres. In more powerful earthquakes,the
fault slips up to five times as much

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