Paolo Favali

Seismicity of the Adriatic microplate

Abstract The Adriatic microplate was previously considered to be a unique block, tectonically active only along its margins. The seismic sequences that took place in the basin from 1986 to 1990 give new information about the geodynamics of this area. Three subsets of well recorded events were relocated by the joint hypocentre determination technique. On the whole, this seismic activity was concentrated in a belt crossing the southern Adriatic sea around latitude 42°, in connection with regional E-W fault systems. Some features of this seismicity, similar to those observed in other well known active margins of the Adriatic plate, support a model of a southern Adriatic lithospheric block, detached from the Northern one. Other geophysical information provides evidence of a transitional zone at the same latitude.

Methane and hydrogen sulfide seepage in the northwest Peloponnesus petroliferous basin (Greece): Origin and geohazard

Gas seepages along the Ionian coast of the northwestern Peloponnesus (Greece), at Killini, Katakolo, and Kaiafas reflect deep hydrocarbon-generation processes and represent a real hazard for humans and buildings. Methane microseepage, gas concentration in offshore and onshore vents, and gas dissolved in water springs, including the isotopic analysis of methane, have shown that the seeps are caused by thermogenic methane that had accumulated in Mesozoic limestone and had migrated upward through faults, or zones of weakness, induced by salt diapirism. A link between local seismicity and salt tectonics is suggested by the analyses of hypocenter distribution. Methane acts as a carrier gas for hydrogen sulfide produced by thermal sulfate reduction and/or thermal decomposition of sulfur compounds in kerogen or oil. Methane seeps in potentially explosive amounts, and hydrogen sulfide is over the levels necessary to induce toxicological diseases and lethal effects.

Mud volcanoes discovered offshore Sicily

Abstract Numerous active mud volcanoes have been recognized for the first time from seismic reflection and sidescan surveys carried out in 2002 over the Hyblean–Malta Plateau, 10 miles from the southern coast of Sicily (Southern Italy, Mediterranean Sea), along faults adjacent to the Scicli fracture zone. Our geophysical data show clearly the presence of several tens of mud volcanoes at water depths between 70 and 170 m. They have scales of order 10 m in diameter and several meters in height. Gas apparently vents from most of the mud volcanoes and is detected acoustically in the sediments around the cones to distances of about 50 m. This discovery represents a new important step in the study of mud volcanism distribution and highlights the potential of the Sicilian shelf as a hydrocarbon-prone area and a natural source of greenhouse gases.

The Gargano promontory: An important Italian seismogenic-tsunamigenic area

Abstract Gargano is a small mountainous promontory protruding into the Southern Adriatic and, from a structural point of view, it is part of the Apulia foreland. Deformative structures, both inland and offshore the promontory, are quite common and can partially be associated with a substantial Quaternary uplifting. Seismogenically this area is well known, because several historical strong earthquakes have been reported to occur here and recent important seismic sequences have been recorded. This paper is a contribution to evaluate the seismogenic as well as the tsunamigenic potential of this region. Particular attention has been given to study the major events, some of which were able to produce tsunamis. The epicenter location of some of these earthquakes computed solely on the basis of macroseismic data would point to focal regions on land, but this is questionable if tsunami generation is taken into account. As regards the tsunamigenic potential, statistical analysis is used to evaluate the local geographical distribution of expected tsunamis and the mean return periods. It is found that large events are expected on average every 228 years, while a tsunami of any size is generated every about 84 years, which is in good agreement with the experimental observations.

ESONET- European sea floor observatory network

ESONET proposes a network of sea floor observatories around the European Ocean margin from the Arctic Ocean to the Black Sea for strategic long term monitoring as part of the European GMES (global monitoring for environment and security) with capability in geophysics, geotechnics, chemistry, biochemistry, oceanography, biology and fisheries. Long-term data collection and alarm capability in the event of hazards (e.g. earthquakes) will be considered. Nine initial areas for ESONET development have been identified and an emergency response capability with mobile stations is proposed.ESONET is a proposed sub sea component of the European GMES (Global Monitoring for Environment and Security) to provide strategic long term monitoring capability in geophysics, geotechnics, chemistry, biochemistry, oceanography, biology and fisheries. To provide representative sampling around Europe 10 nodes are proposed in contrasting oceanographic regions: 1-Arctic, 2-Norwegian margin, 3-Nordic Seas, 4-Porcupine/Celtic, 5-Azores, 6-Iberian, 7-Ligurian, 8-East Sicily, 9-Hellenic, 10-Black Sea. In addition, a mobile response observatory will be available for rapid deployment in areas of anthropogenic or natural disasters to provide data for environment management and government agencies

Mission results from the first GEOSTAR observatory (Adriatic Sea, 1998)

We assess the first mission of the GEOSTAR (GEophysical and Oceanographic STation for Abyssal Research) deep-sea multidisciplinary observatory for its technical capacity, performance and quality of recorded data. The functioning of the system was verified by analyzing oceanographic, seismological and geomagnetic measurements. Despite the mission’s short duration (21 days), its data demonstrated the observatory’s technological reliability and scientific value. After analyzing the oceanographic data, we found two different regimes of seawater circulation and a sharp and deepening pycnocline, linked to a down-welling phenomenon. The reliability of the magnetic and seismological measurements was evaluated by comparison with those made using on-land sensors. Such comparison of magnetic signals recorded by permanent land geomagnetic stations and GEOSTAR during a “quiet” day and one with a magnetic storm confirmed the correct functioning of the sensor and allowed us to estimate the seafloor observatory’s orientation. The magnitudes of regional seismic events recorded by our GEOSTAR seismometer agreed with those computed from land stations. GEOSTAR has thus proven itself reliable for integrating other deep-sea observation systems, such as modular observatories, arrays, and instrumented submarine cables.

Lower Adriatic Sea seismic sequence (January 1986): spatial definition of the seismogenic structure

Abstract In January 1986 a swarm-like seismic sequence (main shock M L = 4.8) took place in the lower Adriatic Sea. This sequence was recorded by the Italian Telemetered Seismological Network using a digital acquisition system. Using additional data collected by other Italian, Yugoslavian and Albanian institutions, 15 shocks of the sequence were located by means of the “master event” technique, and for two of them a focal mechanism solution was obtained. We attempted to frame our results within the knowledge available in the literature. The Adriatic microplate is regarded by many authors as a whole block; nevertheless it exhibits moderate seismicity. The question has arisen as to whether it can be considered an African promontory or whether it behaves independently. The area actived by the sequence is rather small (less than 10 km in diameter) owing to the low level of seismic energy release and does not show any particular trends. The focal mechanisms are consistent with the recent stress field in the Adriatic area inferred from previous studies, which indicate a compression axis oriented NE-SW.

High quality seismological recordings from the SN‐1 deep seafloor observatory in the Mt. Etna region

2002-2003 Framework Program of the Italian National Group for the Defense against Earthquakes (GNDT)

European Seafloor Observatory Offers New Possibilities For Deep Sea Study

The Geophysical and Oceanographic Station for Abyssal Research (GEOSTAR), an autonomous seafloor observatory that collects measurements benefiting a number of disciplines during missions up to 1 year long, will begin the second phase of its first mission in 2000. The 6–8 month investigation will take place at a depth of 3400 m in the southern Tyrrhenian basin of the central Mediterranean. GEOSTAR was funded by the European Community (EC) for

Annual acoustic presence of fin whale (Balaenoptera physalus) offshore Eastern Sicily, central Mediterranean Sea

2.4 million (U.S. dollars) in 1995 as part of the Marine Science and Technology programme (MAST). The innovative deployment and recovery procedure GEOSTAR uses was derived from the “two-module” concept successfully applied by NASA in the Apollo and space shuttle missions, where one module performs tasks for the other, including deployment, switching on and off, performing checks, and recovery. The observatory communication system, which takes advantage of satellite telemetry, and the simultaneous acquisition of a set of various measurements with a unique time reference make GEOSTAR the first fundamental element of a multiparameter ocean network.