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  • 1
    Publication Date: 2017-03-01
    Description: The eastern flank of the Mount Etna stratovolcano is affected by extension and is slowly sliding eastward into the Ionian Sea. The Pernicana fault system forms the border of the northern part of this sliding area. It consists of three E-W–oriented fault sectors that are seismically active and characterized by earthquakes up to 4.7 in magnitude (M) capable of producing ground rupture and damage located mainly along the western and central sectors, and by continuous creep on the eastern sector. A new topographic study of the central sector of the Pernicana fault system shows an overall bell-shaped profile, with maximum scarp height of 35 m in the center of the sector, and two local minima that are probably due to the complex morphological relation between fault scarp and lava flows. We determined the ages of lava flows cut by the Pernicana fault system at 12 sites using cosmogenic 3 He and 40 Ar/ 39 Ar techniques in order to determine the recent slip history of the fault. From the displacement-age relations, we estimate an average throw rate of ~2.5 mm/yr over the last 15 k.y. The slip rate appears to have accelerated during the last 3.5 k.y., with displacement rates of up to ~15 mm/yr, whereas between 3.5 and 15 ka, the throw rate averaged ~1 mm/yr. This increase in slip rate resulted in significant changes in seismicity rates, for instance, decreasing the mean recurrence time of M ≥ 4.7 earthquakes from ~200 to ~20 yr. Based on empirical relationships, we attribute the variation in seismic activity on the Pernicana fault system to factors intrinsic to the system that are likely related to changes in the volcanic system. These internal factors could be fault interdependencies (such as those across the Taupo Rift, New Zealand) or they could represent interactions among magmatic, tectonic, and gravitational processes (e.g., Kīlauea volcano, Hawaii). Given their effect on earthquake recurrence intervals, these interactions need to be fully assessed in seismic hazard evaluations.
    Print ISSN: 0016-7606
    Electronic ISSN: 1943-2674
    Topics: Geosciences
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  • 2
    Publication Date: 2022-08-25
    Description: Subito dopo l’evento del 6 aprile 2009, come di consueto è stata realizzata una lunga e complessa indagine macrosismica, promossa dal gruppo operativo QUEST, che ha avuto inizialmente l’obiettivo di delimitare l’area di danneggiamento, a supporto delle attività di pronto intervento della Protezione Civile, e successivamente quello di classificare nel modo più accurato e capillare possibile, gli effetti prodotti dall’evento, particolarmente nelle aree danneggiate. A questo scopo è stata prodotta una stima utilizzando la scala MCS (Sieberg, 1930); in un secondo momento è stata rifinita l’indagine per una cinquantina di località dell’area maggiormente danneggiata (Is MCS〉VII), raccogliendo ed elaborando i dati in termini di scala macrosismica EMS98 (Grünthal, 1998). Per la complessità e la dimensione dei problemi affrontati, questo terremoto ha costituito un banco di prova di grande importanza per la macrosismologia italiana. In questo testo viene descritto il lavoro realizzato, discutendo in particolare alcuni aspetti che hanno messo alla prova le metodologie di indagine tradizionali (sistematiche irregolarità degli insediamenti monitorati, forti divergenze degli scenari di danno rispetto a quelli previsti dalle scale, difficile comparabilità con scenari storici, ecc.) e presentandone i risultati, in relazione ai parametri epicentrali che ne risultano e il loro contributo più diretto alla comprensione complessiva della sismicità dell’area.
    Description: Published
    Description: 49-55
    Description: 1.11. TTC - Osservazioni e monitoraggio macrosismico del territorio nazionale
    Description: N/A or not JCR
    Description: open
    Keywords: intensità macrosismica ; L'Aquila 2009 ; danneggiamento ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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