Description: GEOSTAR is the prototype of the first European long-term, multidisciplinary deep sea observatory for continuous monitoring of geophysical, geochemical and oceanographic parameters. Geostar is the example of a strong synergy between science and tecnology addressed to the development of new technological solutions for the observatory realisation and management. The GEOSTAR system is described outlining the enhancements introduced during five years of project activity. An example of data retrieved from the observatory being the deep sea mission running is also given.

Description: Published

Description: 111-120

Description: 2.5. Laboratorio per lo sviluppo di sistemi di rilevamento sottomarini

Description: reserved

Description: Exploration of ocean seafloor is of paramount importance for a better understanding of the geodynamic evolution of our Planet. The pilot experiment of ORION-GEOSTAR 3 EC project was the first long-term continuous geophysical and oceanographic experiment of an important seafloor area of Southern Tyrrhenian Sea, the Marsili abyssal plain. The latter hosts the Marsili Seamount which is Europe’s one of the largest underwater volcano of Plio-Pleistocenic age. In spite of its dimensions, it is rather unknown about the present characteristics and activity. For this reason, we deployed a deep-sea observatory network, composed by two bottom observatories, on the seafloor at the base of the seamount at 3320 m b.s.l., in the period December 2003-May 2005. Some of the instruments on board the observatory were: broad-band seismometers, hydrophones, gravity meter, two magnetometers (scalar and vectorial), 3D single-point current meter, ADCP, CTD, automatic pH analyser and off-line water sampler for laboratory analyses. The first successful scientific objective was to obtain long-term continuous recordings under a unique time reference. The data analysis shows that they are generally of good quality and really continuous (only a few gaps). As a first step we performed a classification of seismic waveforms, a first inversion of magnetic variational data, and a first analysis of gravity meter, chemical and oceanographic data. Analysis of individual time series has shown interesting results, i.e. depth of the magnetic Moho under the Marsili, attenuation of recorded seismic body waves and clues of hydrothermal circulation. We show examples of the preliminary data analysis together with first results and comparisons among data coming from different sensors.

Description: Published

Description: Cambridge, UK, February 24-26, 2009

Description: 1.8. Osservazioni di geofisica ambientale

Description: 3.8. Geofisica per l'ambiente

Description: open

Description: La caldera risorgente dei Campi Flegrei è, insieme ai vulcani Somma-Vesuvio, Ischia e Procida, uno degli elementi dominanti dell’assetto geologico e morfologico dell’area napoletana. Si tratta di un sistema vulcanico ancora attivo la cui persistente attività è testimoniata dall’ultima eruzione, avvenuta nel 1538, dall’intensa attività fumarolica e idrotermale che perdura da millenni e dai frequenti eventi bradisismici, con deformazione del suolo accompagnata da sismicità e variazioni delle caratteristiche chimico-fisiche dei fluidi emessi dalle fumarole. La caldera comprende la parte occidentale della città di Napoli e si estende nel Golfo di Pozzuoli. La caratteristica principale dell’attuale attività vulcanica della caldera è il movimento lento del suolo a carattere episodico e di grande ampiezza (bradisismo), accompagnato da un’intensa e superficiale attività sismica che si verifica in generale durante la fase di sollevamento......

Description: Istituto Nazionale di Geofisica e Vulcanologia - Marina Militare Italiana

Description: Published

Description: 6A. Monitoraggio ambientale, sicurezza e territorio

Description: open

Description: A new concept gravity meter with sensitivity close to Hz ms / 10 2 8 − − in the range of 10 -5 −1Hz intended for observation of the vertical component of the Earth gravity and teleseismic waves was implemented at the Istituto di Fisica dello Spazio Interplanetario (IFSI), CNR and successfully operated during the GEOSTAR-2 mission. The gravimeter has demonstrated a capability to operate for long time in an autonomous regime and a good reliability for operation in extreme environments; at the same time the experimental measurements gave the information for the further gravimeter’s implementation. Results of observation and data analysis included the registration of seismic waves excited by global earthquakes and the evaluation of the low frequency modes of free oscillations of the Earth are reported.

Description: JCR Journal

Description: open

Description: Important processes that affect the Earth, for example climate change and geohazards, are driven by phenomena that take place in the oceans. To better understand and mitigate the effects of these processes, an important international effort is taking place to deploy permanent and remotely controlled seafloor and water-column observatory systems. In Europe, large cabled systems with marine sensors are being developed for near real-time and real-time long-term monitoring of ocean processes. Many of these system are part of the EMSO (European Multidisciplinary Seafloor and water column Observatory www.emso-eu.org) Research Infrastructure. A multidisciplinary approach based on different types of sensors, is necessary to understand complex natural phenomena. In fact, given a signal of interest, by using several sensors recording simultaneously it is possible to identify the contribution of different sources to this signal. On the other hand, obtaining good quality long-term continuous data from a variety of sensors installed on a seafloor observatory can be a challenging technical task. We consider long-term time series acquired by GEOSTAR class seafloor observatories deployed at two European offshore sites (Western Ionian sea in the Mediterranean and Iberian Margin-Gulf of Cadiz in the Atlantic Ocean), where there are important sources of geohazard. The observatories are either standalone or cabled, each with its particular technological difficulties and features. The quality and reliability of a signal depends on a chain of events defined by the following aspects: the sensor itself, the installation procedure of the sensor, the possible interaction of the sensor with nearby electronics or with other sensors (e.g. active acoustic current meters signal is recorded from hydrophones), the time stamping procedure, the architecture of data acquisition and transmission (or storage in the standalone case) system, and finally data processing to improve signal to noise ratio. The definition of what is signal and what is noise depends on the study of interest. For example, a seismologist interested in the signals that are caused by earthquakes considers environmental and anthropic effects as noise which would be gladly removed. On the other hand, if one is trying to study the seasonal variations of the seismic signal, then this contribution becomes the signal of interest. To correlate time series coming from different sites, campaigns or instruments, absolute calibration of sensors is obviously a critical issue. A rigorous estimate of timestamp precision is needed to achieve reliable results from multidisciplinary studies. In the present work we focus on the quality of the signal recorded by a broadband seafloor seismometer (from 0.003 Hz to 50 Hz), by a prototype gravimeter and on signals recorded by auxiliary sensors that are helpful in discriminating different noise sources. We first illustrate the steps that were taken to obtain a good quality reliable signal and finally we focus on how, thanks to a multisensor approach, we can identify the main noise sources, such as sea currents and temperature variation in the long period part of the spectrum. It is possible, in principle, to reduce this noise through signal processing techniques. The improvement of the S/N with such procedures allows for a more efficient detection of interesting seismic signals. We show some examples of this signal improvement procedure.

Description: Published

Description: Genova

Description: 3A. Ambiente Marino

Description: restricted

Description: Gravity time sequences collected at Etna volcano by continuously recording spring-based relative gravimeters showed significant variations in temporal correspondence with paroxysmal eruptions. Since the observed gravity variations can only be partially related to subsurface mass redistribution phenomena, we investigated on the instrumental effects due to the ground vibrations as those accompanying explosive activity. We simulated the performances of relative gravimeters through laboratory experiments to estimate their response to vertical and horizontal excitations. Laboratory tests were carried out using a vibrating platform capable of accelerating the instruments with intensities and frequencies, in both the vertical and horizontal directions, observed in the ground vibrations associated with paroxysmal events. The seismic signals recorded at Etna volcano during the 10 April 2011 lava fountain were analyzed to retrieve the parameters used to drive the vibration platform. We tested two gravimeters used for Etna volcano monitoring: the LaCoste & Romberg D#185 and the Scintrex CG-3M#9310234. The experimental results highlight that vibrations, resembling the seismic waves propagated during paroxysmal events, cause an amplitude response in the gravity readings of the order of several hundred of microGals. Generally the relationship between the vibrations and the gravimeter response is non-linear with a fairly complex dependence on the frequencies and amplitude of the signals acting on the gravimeters.

Description: Published

Description: 44

Description: 2V. Dinamiche di unrest e scenari pre-eruttivi

Description: JCR Journal

Description: open

Description: The European project “Wind, Ports, and Sea”, funded by the European Cross-border Programme “Italy–France Maritime 2007-2013”, aims to improve the safety conditions and to reduce the hazards by monitoring and forecasting the sea-state outside the main ports of the Northern Tyrrhenian and Ligurian Seas. The sea state forecast is done by using a numeric model specifically developed, while the used data are obtained by means of a monitoring system of stations installed in the coast of La Spezia harbor so to perform an inland remote monitoring. This remote monitoring system of the sea, called OSIS ® (Ocean Seismic - Integrated Solution), is a pilot project and will be presented in its main features. The main advantage of the OS-IS® is that it is installed inland and there are no parts in the sea. The key elements of the system are a high sensitivity accelerometers and apposite algorithms for the evaluation of the sea state using the micro-seismic signals on the basis of the mathematical models and the appropriate calibration factors. Actually, since the beginning of the 1900, is well known that the sea waves are sources of a microseismic noise and this phenomenon has been described with more and more precise models since the 1950 by Longuet-Higgins. The OS-IS® system used for "Wind, Ports and Sea" project is made of three micro-seismic stations installed near the La Spezia gulf: each accelerometric station is equipped with a weather station and a data logger that automatically transfers the data to a central server which runs the algorithm of the OS-IS®. In the following will be shortly described the installed systems focusing on its reliability and in the comparison with the traditional monitoring system using buoy. Finally the first measurements will be shown in comparison with those of the conventional method based on the buoys.

Description: Autorità Portuale della Spezia, Programma di cooperazione transfrontaliera Italia-Francia “Marittimo” 2007-2013

Description: Published

Description: 691-698

Description: 3A. Ambiente Marino

Description: N/A or not JCR

Description: restricted