Publication Date:
2022-06-14
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 3He and 40Ar/39Ar techniques
in order to determine the recent slip
history of the fault. From the displacementage
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.
Description:
Published
Description:
304-317
Description:
1V. Storia e struttura dei sistemi vulcanici
Description:
JCR Journal
Description:
open
Keywords:
Etna
;
04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
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