Publication Date:
2017-04-04
Description:
The development of the 2004–2005 eruption at Etna (Italy) is investigated by means of field surveys to define the current
structural state of the volcano. In 2004–2005, a fracture swarm, associated with three effusive vents, propagated downslope from
the SE summit crater towards the SE. Such a scenario is commonly observed at Etna, as a pressure increase within the central
conduits induces the lateral propagation of most of the dikes downslope. Nevertheless, some unusual features of this eruption
(slower propagation of fractures, lack of explosive activity and seismicity, oblique shear along the fractures) suggest a more
complex triggering mechanism. A detailed review of the recent activity at Etna enables us to better define this possible mechanism.
In fact, the NW–SE-trending fractures formed in 2004–2005 constitute the southeastern continuation of a N–S-trending fracture
system which started to develop in early 1998 to the east of the summit craters. The overall 1998–2005 deformation pattern
therefore forms an arcuate feature, whose geometry and kinematics are consistent with the head of a shallow flank deformation on
the E summit of Etna. Similar deformation patterns have also been observed in analogue models of deforming volcanic cones. In
this framework, the 2004–2005 eruption was possibly induced by a dike resulting from the intersection of this incipient fracture
system with the SE Crater. A significant acceleration of this flank deformation may be induced by any magmatic involvement. The
central conduit of the volcano is presently open, constantly buffering any increase in magmatic pressure and any hazardous
consequence can be expected to be limited. A more hazardous scenario may be considered with a partial or total closing of the
central conduit. In this case, magmatic overpressure within the central conduit may enhance the collapse of the upper eastern flank,
triggering an explosive eruption associated with a landslide reaching the eastern lower slope of the volcano.
Description:
Published
Description:
195–206
Description:
reserved
Keywords:
eruption triggering
;
volcano-tectonics
;
fracture fields
;
flank spreading
;
Mt. Etna
;
04. Solid Earth::04.04. Geology::04.04.01. Earthquake geology and paleoseismology
;
04. Solid Earth::04.04. Geology::04.04.09. Structural geology
;
04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
Format:
2594507 bytes
Format:
application/pdf
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