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Lab Records Sounds Of March 11 Japan Earthquake And Aftershocks From Underwater Observatories

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BARCELONA, Spain -- The Laboratory of Applied Bioacoustics (LAB), a unit of the Universitat Politècnica de Catalunya (UPC), directed by Professor Michel André, has recorded the sound of the earthquake that shook Japan on Friday, March 11. The recording, now available online, was provided by a network of underwater observatories belonging to the Japan Agency for Marine-Earth Science and Technology (JAMSTEC) and located on either side of the earthquake epicenter, close to the Japanese island of Hatsushima.

The UPC laboratory is using this platform as part of Listening to the Deep Ocean Environment (LIDO), a LAB-led international project. "LIDO aims, for the first time ever, to record deep-sea sounds in real time and determine how artificial sounds impact the conservation states of the marine environment," says Michel André.

Equipped with hydrophones for monitoring underwater sounds in real-time over the Internet, the LIDO system has been continuously recording the sound of the earthquake and its aftershocks. LIDO obtains automatic recordings of the acoustic events detected. Sources are then identified and classified as being of biological or anthropogenic origin. The system can be used to listen simultaneously to what is happening at different observatories.

On March 11, 2011, at 2:45 p.m. Japanese local time, the LIDO system acoustically detected and recorded the earthquake at JAMSTEC observatories located off the coast off Kushiro and Hatsushima. The recording is available on the LIDO website The sound of the earthquake and two aftershocks registered by these two Japanese observatories is available in the "Sound Library" section of the website (under "Earthquakes"). The data published there have been accelerated 16 times so that they can be audible to human ears. In the "Listen on Site" section of the same website, visitors can also listen to, and view, a live stream of the acoustic data in which aftershocks are continuously perceptible.

The spectrograms shown on the website reflect, both acoustically and visually, the intensity and energy distribution of the earthquake sound. The images illustrate the frequency and intensity of the sound by means of a spectrum of colors (with red and yellow being the most intense).

The earthquake's effect on Japan's underwater ecosystem pales in comparison to its dramatic impact on the country's population. Nevertheless, due to their sensitivity to noise, cetaceans are considered valuable bioindicators of the natural acoustic balance of oceans. Their sensitivity and their crucial role in ecosystems have already made it possible to determine the tolerance of the food chain to exposure to artificial sound sources.

The LIDO system has given access to these exceptional geophysical data—from Japan and other seismically active geographical areas around the world—that are already being used in other disciplines as bioindicators of the natural balance of the oceans. They can now assist in the development of models that would integrate the reaction of cetaceans to noise as a geohazard indicator in the event of major seismic activity.

The website also offers the general public the opportunity to witness the earthquake and follow its evolution in real time.

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