Quick tsunami sensors tested in Mediterranean
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).
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 communication and response mechanisms throughout the NEATWS network.
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.
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.
Rachid Omira, a geophysicist at the Portuguese Institute for the Sea and Atmosphere, Lisbon, tells SciDev.Net 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.
Francesco Chierici, a physicist at Italy's Radioastronomy Institute and at the Institute of Marine Sciences, both in Bologna, tells SciDev.Net that the current system uses seismic signals to assess such things as the location, depth and strength of tremors.
"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 water movements with coastal tide gauges," he says.
"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."
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.
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.
To bypass the problem, the team lead by Chierici is testing two new techniques, including a multi-sensor detector.
"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.
Continue reading at ENN affiliate, SciDev.Net.
Tsunami destruction image via Shutterstock.