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<DIV class=article-banner-title><FONT size=5><STRONG>Quicker tsunami sensors
tested in Mediterranean</STRONG></FONT></DIV>
<DIV>Giovanni Sabato</DIV>
<DIV>20/11/13</DIV>
<DIV class=article-banner-title><A
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<P class=image-caption>[ROME] A new alert system could improve tsunami warnings
in the Mediterranean, but most countries bordering the sea still lack evacuation
plans, scientists have said ahead of a meeting of 20 countries in Italy this
week (19-21 November).<BR> <BR>The tenth session of the Intergovernmental
Coordination Group for the North-Eastern Atlantic, Mediterranean and connected
seas, Tsunami Warning and Mitigation System (NEAMTWS) will discuss establishing
new national tsunami warning centres. It will also work towards organising the
next tsunami exercise, a simulation of tsunami alerts following several
different kinds of earthquakes, to evaluate the <A
href="http://www.scidev.net/global/communication/">communication</A> and
response mechanisms throughout the NEATWS network.<BR> <BR>NEAMTWS member
states include Algeria, Egypt, Lebanon, Libya, Morocco, Tunisia and Turkey. All
member countries are signed up to receive the alerts the NEAMTWS network
provides.<BR> <BR>The current alert system implemented by NEATWS relies on
earthquake detection and tide gauges to see if a tsunami has been generated, but
in the enclosed Mediterranean Sea it suffers from various challenges arising
from local geography.<BR> <BR>Rachid Omira, a geophysicist at the
Portuguese Institute for the Sea and Atmosphere, Lisbon, tells
<EM>SciDev.Net</EM> that the current system includes French, Greek and Turkish
institutions that are being accredited by NEAMTWS as official tsunami alert
providers for the whole Mediterranean region. Two more providers are being
planned in Italy and Portugal.<BR> <BR>Francesco Chierici, a physicist at
Italy’s Radioastronomy Institute and at the Institute of Marine Sciences, both
in Bologna, tells <EM>SciDev.Net</EM> that the current system uses seismic
signals to assess such things as the location, depth and strength of
tremors.<BR> <BR>“If an earthquake is detected and its characteristics are
such that it can potentially trigger a tsunami, a provisional alarm is launched
and then confirmed or cleared by measuring <A
href="http://www.scidev.net/global/environment/water/">water</A> movements with
coastal tide gauges,” he says.<BR> <BR>“But presently we do not know if,
after a major earthquake at sea, a destructive tsunami would be generated or
not. And false alarms can be very hazardous and costly.”<BR> <BR>In other
places around the world, tsunami warning systems include deep-ocean offshore
stations that record water pressure, confirming the tsunami and following its
spread in real time, Chierici says.<BR> <BR>But in the Mediterranean the
geological faults, which need to be monitored for earthquakes, are often near
the coasts, where deep-ocean offshore stations do not work well.<BR></P>
<P class=image-caption>To bypass the problem, the team lead by Chierici is
testing two new techniques, including a multi-sensor detector.<BR> <BR>“We
are experimenting with a new, deep-sea tsunameter that, beyond sensing the water
pressure, has a seismometer and an accelerometer that measures the movements of
the sea bottom. This way we can distinguish the tsunami signal from those
movements,” Chierici says.<BR> <BR>In collaboration with scientists from
two other Italian science institutes, Chierici was involved in the European
Union-funded NEAREST project (Integrated observations from NEAR shore sourcES of
Tsunamis).<BR> <BR>They tested the tsunameter to the south of Portugal in
the Gulf of Cadiz, and are continuing their tests off Sicily,
Italy.<BR> <BR>“It’s working well and I’m optimistic about its success. It
could help in other areas that need a quick alert, such as Indonesia,” Chierici
says.<BR><BR><STRONG>Listening out for tsunamis</STRONG></P>
<P class=image-caption>A second technique under test would be even better for
rapidly detecting tsunamis generated by various mechanisms, not only
earthquakes, he says. It uses submarine sensors to detect hydroacoustic waves,
sound waves produced by the sea-floor motion that generates the tsunami. These
sound waves spread up to ten times faster than the tsunami wave
itself.<BR> <BR>“The tsunami would be detected faster and regardless of its
origin: not only [a tsunami] from an earthquake but also from a volcano or a
submarine landslide,” he says.<BR> <BR>“But we are just beginning the tests
and it’s uncertain if it will work. Similar sounds are produced by other sources
and discriminating [between them] is difficult.”<BR> <BR>According to Omira
the new systems would help, but an important issue is what to do once an alert
is sent out. Most countries bordering the Mediterranean lack evacuation plans,
he says.<BR> <BR>“The idea is there, but plans are still not being
implemented,” he says. “Presently, the single most-useful intervention would be
educating the population: if they are near the sea and feel an earthquake, they
have to run to higher ground without waiting for the
alert.”<BR></P></FONT></BODY></HTML>