Permanent deep-sea seismic sensors

Jun 06, 2005

A submarine seismic sensor was recently set in place at 2400 m depth, off Toulon. The instrument was attached to a neutrino telescope developed by the international scientific programme Antares. For the first time in Europe, this sensor, designed by a partnership between Géosciences Azur (Mixed Research Unit IRD/CNRS/UPMC/UNSA, Villefranche sur Mer) and Guralp System (United Kingdom), with the financial support of INSU, Villefranche Oceanological Observatory and the Provence-Alpes-Côte d'Azur Regional Council, can send real-time deep-sea seismic activity data recorded for the region and for the whole world.

Deployment of this broad-band sensor by the IFREMER ROV "Victor" allows testing of the installation parameters necessary for accurate observation of earthquakes that occur locally, within the region or elsewhere throughout the globe. The project has also resulted in new developments in deep-ocean technology and skills.

Three great challenges face scientists in efforts to achieve high-quality long-term observation: resistance of instruments and cables to enormous deep-sea water pressures; resistance of instruments to corrosion in the marine environment; and perfect coherence between the equipment and the electronic systems incorporated to ensure remote control and monitoring.

The Antares programme conducted off Toulon, for which the CPPM at Marseille-Luminy University is the host laboratory, gave the Géosciences Azur team a unique opportunity to take up these challenges and develop seismological techniques that could subsequently be 'exported' for application in the world's earthquake zones. In several coastal regions of the globe, seismic risk comes from strong submarine earthquakes that can occur. Accurate study of such activity is therefore important for devising improved risk-assessment systems. That is why marine sensors are necessary.

The observation tools scientists currently have at their disposal for conducting research programmes are stand-alone seismological sensors or OBSs (Ocean Bottom Seismometers), cast off from the surface with their batteries and built-in memory which confers several months' recording capacity. They come to rest freely on the ocean floor. At the end of the prescribed recording period they are brought to the surface by remote control. However, data analysis cannot be performed until the seismometer has been retrieved.

Even though it is not a means of earthquake prediction, seismological surveillance can allow rapid assessment of an event's magnitude and location; and hence of their impact. It requires real-time transmission of data provided by the sensor networks in place.

In this aspect too, the experiment under way is bringing with it an improvement in reliability of the technological systems used: digital ground movement recordings made by the sensor are transmitted by a 40 km long cable which links all the elements of the Antares experiment to the coast; from there they are relayed by the Internet to the Géosciences Azur laboratory.

The laboratory's next objective is to deploy a similar sensor in the Ligurian Sea in order to complete its regional earthquake watch system.

Source: Institut de Recherche Pour le Développemen

Explore further: New method makes space weather easier to predict

add to favorites email to friend print save as pdf

Related Stories

Key facts on US 'open Internet' regulation

33 minutes ago

A landmark ruling by the US Federal Communications Commission seeks to enshrine the notion of an "open Internet," or "net neutrality." Here are key points:

Spotify deals with random shuffle and we mortals

34 minutes ago

How do we mortals perceive random sequences? An entry in the question-and-answer site Quora focused on a question involving a music-streaming service Spotify. That question signifies how we perceive what ...

Top-precision optical atomic clock starts ticking

35 minutes ago

A state-of-the-art optical atomic clock, collaboratively developed by scientists from the University of Warsaw, Jagiellonian University, and Nicolaus Copernicus University, is now "ticking away" at the National ...

Cats put sight over smell in finding food

58 minutes ago

Cats may prefer to use their eyes rather than follow their nose when it comes to finding the location of food, according to new research by leading animal behaviourists.

'Bright spot' on Ceres has dimmer companion

23 minutes ago

Dwarf planet Ceres continues to puzzle scientists as NASA's Dawn spacecraft gets closer to being captured into orbit around the object. The latest images from Dawn, taken nearly 29,000 miles (46,000 kilometers) ...

Recommended for you

New method makes space weather easier to predict

20 minutes ago

Scientists can now gain a better understanding of space weather – the dreaded solar winds and flares – thanks to the development of high spatial resolution observation and computing methods. For the first ...

Mystery giant Mars plumes still unexplained

30 minutes ago

On Feb. 16, an international group of researchers proposed new hypotheses about some unusual plumes spotted by amateur astronomers on Mars in 2012. The plumes were seen rising to altitudes of over 250 km ...

Where do stars form in merging galaxies?

32 minutes ago

Collisions between galaxies, and even less dramatic gravitational encounters between them, are recognized as triggering star formation. Observations of luminous galaxies, powered by starbursts, are consistent ...

Hunting transiting exoplanets

48 minutes ago

European Southern Observatory (ESO) gears up for the exoplanet hunting. The Next-Generation Transit Survey (NGTS), a wide-field observing system made up of an array of twelve telescopes was installed at ESO's ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.