Name of the SA: NEMO-SN1
Institute: INGV – Istituto Nazionale di Geofisica e Vulcanologia
Short SA Description:
NEMO-SN1: Western Ionian Sea geophysical and enviromental monitoring
The scientific objectives of the real-time cabled NEMO-SN1 observatory covers a wide range of research activities in deep sea: High Energy Astrophysics, Physical Oceanography, Bio-acoustics, Environmental Sciences, Geophysics and Geo-Hazards contributing to answer to the societal needs. The large set of sensors installed in the observatory (seismometer, hydrophones, pressure sensors, gravity meter, magnetometers, current meters, CTD) refers to this large variety of discipline.
Of particular relevance is a prototype of tsunameter specifically designed to operate in tsunami generation areas, able to detect also hydroacoustic signals that can be possible precursor of tsunami generation. The Western Ionian area, where NEMO-SN1 is located, is one of the most seismically active areas of the Mediterranean and for this reason is very appropriate for the tsunameter operation assessment. For the first time, studies based on correlation between tsunameter alert signals, magnetometers signals and low frequency acoustic waves -recorded by deep-sea hydrophones- will be carried on, with the aim of improving reliability of the tsunami early alert system in this prone area for tsunamis.
Another interesting feature of the area is the vicinity of Mount Etna, one of the largest and active volcanoes in Europe. The roots of this volcano possibly sink down to seafloor depth but the actual extension is almost unknown and some geophysical measurements at sea (gravimetric and magnetic), together to analogous ones on land, can strongly help to gain a better knowledge.
The NEMO-SN1 deployment area is also a key site for the oceanographic circulation between Eastern and Western Mediterranean Sea through the Messina Strait/ and the Sicily Channel.
The acoustic detectors are used for passive acoustic detection of cetaceans to localise and fully track them. The monitoring of marine mammals can contribute to study the population trends in relation to climate changes and human impacts. NEMO-SN1 has already contributed to individuate in the area an unprecedented and huge number of sperm whales, up to then given for disappeared, with daily detection.
Figure 1. Fin whale detection using data from hydrophone installed on NEMO-SN1. Observed fin whale call types. Spectrograms (8192 points FFT, 2048 points Hanning window, 97% overlap) of two typical calls of the Mediterranean fin whale. (a) type A or “classic pulse” and (b) type B or “back-beat” are here showed in detail. [picture from Sciacca et al. (2015) Annual Acoustic Presence of Fin Whale (Balaenoptera physalus) Offshore Eastern Sicily, Central Mediterranean Sea. PLoS ONE 10(11): e0141838. doi:10.1371/journal.pone.0141838.g004
Figure 2: Analysis of NEMO-SN1magnetometer data and comparison to land installation. The spectra of data measured from NEMO-SN1 and LMP observatories during: (A) magnetically quiet days (23–24 September 2012) and (B): disturbed days (14–15 July 2012). C and D are the spectra for each site during quiet and disturbed periods. [Picture from Monna et al. Underwater geophysical monitoring for European Multidisciplinary Seafloor and water column Observatories, Journal of Marine Systems 130 (2014) 12–30, doi: 10.1016/j.jmarsys.2013.09.010
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