Tsunami earthquake sound record was not shared to the world

(CNN) -- Scientists are gaining insight about December's devastating
earthquake and tsunami from the actual sounds of the magnitude 9.3 quake in
the Indian Ocean.

"It's really quite an eerie sound to hear the earth ripping apart like that.
We hear it on smaller earthquakes quite frequently but something of this
scale that goes on for eight minutes is very much unprecedented," said Maya
Tolstoy, a marine geophysicist at Columbia University's Lamont-Doherty Earth
Observatory.

"It really gave me the chills when I first heard it," she said.

The dramatic soundtrack of the rupture of the Sumatra-Andaman Fault comes
from a little known, and sometimes hard- to- access resource. The
microphones that captured the sound are part of a global network of
instruments that monitor compliance with the Comprehensive Nuclear Test Ban
Treaty.

The microphones that picked up this earthquake were located in Diego Garcia,
an island more than 1,700 miles from the epicenter of the quake.

The sounds suggest two distinct stages of the underwater temblor.

"What we are able to see is very clearly two phases in the speed of the
rupture," said Tolstoy.

"The first third is much faster, the second two thirds slower," she said.
The length of the rupture was about 750 miles.

"I look at it mathematically and I study the change in direction of the
earthquake," she said. "We are able to tell how long it ruptured, how fast
it went, and those are important things to know for disaster mitigation,"
she said.

Tolstoy and other scientists have had some access to data from the
monitoring group, The Preparatory Commission for the Comprehensive Nuclear
Test Ban Treaty Organization (CTBTO). In the past researchers have obtained
the sounds of other earthquakes, and even the noises made when icebergs
cracked.

But a spokeswoman for CTBTO, headquartered in Vienna, Austria, says the
group does not have the capability to act as a disaster alert system.

"Our mandate is watching for nuclear weapons testing," said Daniela
Rozgonova. "We don't share data directly with scientists. Our data is
collected and analyzed, and goes to member states. They decide what to do
with it," she said. A total of 121 countries have ratified the nuclear test
ban treaty, agreeing "not to carry out any nuclear weapon test explosion or
any other nuclear explosion, and to prohibit and prevent any such nuclear
explosion at any place under its jurisdiction or control."

But because of the deaths and destruction of last year's Asian tsunami,
Rozgonova did say the organization would now share seismic observation data
with UNESCO, the United Nations Educational, Scientific, and Cultural
Organization. That group is working with many countries that are trying to
improve early warning systems for tsunamis. But she stressed there is no way
the information could be relayed "real time."

"It's a very sensitive issue obviously because you are monitoring the globe
and you can hear relatively small sounds, and so countries are very
sensitive about having that information openly released," said Tolstoy.

Tolstoy's research based on the earthquake sounds is published in the
July/August issue of Seismological Research Letters.

She said she and other scientists, like many people around the world, felt a
real helplessness in watching the effects of the tsunami.

"We obviously can't prevent earthquakes but we'd like to be able to help
prevent as much of the damage as possible from a tsunami by providing
warning where it's possible. So in the long term we want to better
understand how these events happen so we can better mitigate against them,"
she said.