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Holocene slip rate variability along the Pernicana fault system (Mt. Etna, Italy); evidence from offset lava flows

D. D'Amato, B. Pace, L. Di Nicola, F. M. Stuart, F. Visini, R. Azzaro, S. Branca and S. Barfod
Holocene slip rate variability along the Pernicana fault system (Mt. Etna, Italy); evidence from offset lava flows
Geological Society of America Bulletin (October 2016) 129 (3-4): 304-317

Abstract

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 (super 3) He and (super 40) Ar/ (super 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 approximately 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 approximately 15 mm/yr, whereas between 3.5 and 15 ka, the throw rate averaged approximately 1 mm/yr. This increase in slip rate resulted in significant changes in seismicity rates, for instance, decreasing the mean recurrence time of M > or = 4.7 earthquakes from approximately 200 to approximately 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., Kilauea volcano, Hawaii). Given their effect on earthquake recurrence intervals, these interactions need to be fully assessed in seismic hazard evaluations.


ISSN: 0016-7606
EISSN: 1943-2674
Coden: BUGMAF
Serial Title: Geological Society of America Bulletin
Serial Volume: 129
Serial Issue: 3-4
Title: Holocene slip rate variability along the Pernicana fault system (Mt. Etna, Italy); evidence from offset lava flows
Affiliation: Universita "G. d'Annunzio", Dipartimento di Scienze Pisicologiche, della Salute e del Territorio, Chieti, Italy
Pages: 304-317
Published: 20161021
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 102
Accession Number: 2016-094603
Categories: Quaternary geologyStructural geology
Document Type: Serial
Bibliographic Level: Analytic
Annotation: Data repository item 2016306
Illustration Description: illus. incl. 2 tables, sketch maps
N37°45'00" - N37°47'60", E15°01'00" - E15°10'00"
Secondary Affiliation: Scottish Universities Environmental Research Centre, GBR, United KingdomIstituto Nazionale di Geofisica e Vulcanologia, ITA, Italy
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2019, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 201646
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