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

D'Amato, D., Pace, B., Di Nicola, L., Stuart, F.M. , Visini, F., Azzaro, R., Branca, S. and Barfod, D.N. (2017) Holocene slip rate variability along the Pernicana fault system (Mt. Etna, Italy): Evidence from offset lava flows. Geological Society of America Bulletin, 129(3-4), pp. 304-317. (doi:10.1130/B31510.1)

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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 3He and 40Ar/39Ar 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.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Barfod, Dr Dan and Di Nicola, Dr Luigia and Stuart, Professor Finlay
Authors: D'Amato, D., Pace, B., Di Nicola, L., Stuart, F.M., Visini, F., Azzaro, R., Branca, S., and Barfod, D.N.
College/School:College of Science and Engineering > Scottish Universities Environmental Research Centre
Journal Name:Geological Society of America Bulletin
Publisher:Geological Society of America
ISSN:0016-7606
ISSN (Online):1943-2674
Published Online:01 October 2016
Copyright Holders:Copyright © 2016 The Authors
First Published:First published in Geological Society of America Bulletin 129(3-4):304-317
Publisher Policy:Reproduced under a Creative Commons License

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