Publication Date:
2017-04-04
Description:
Over the past few decades we have been intensively monitoring the magnetic field on
Mt. Etna. The largest anomaly, about 10 nT, was observed in the geo-magnetic time
series recorded in 1981 and associated with the March 17-23 eruption. It was interpreted
as the joint effect of piezomagnetism and thermal demagnetization engendered by an
intrusive dike. A convincing case of thermo-magnetic effects was observed during the
1989 fissure eruption, when repeated measurements at intervals of 3 months for two
years revealed the slow buildup of a 130 nT anomaly. The anomaly vanished laterally
within 0.2 km from the sur-face expression of the fissure system. The nature and
structure of the anomaly is consistent with the location and time of cooling of a shallow
dike. Between Sep-tember and December 1995 geomagnetic changes, greater than 8 nT,
associated with the renewal of the NE crater's activity were detected. The center of the
magnetic anomaly source, which was thought to be the region heated by hightemperature
fluids and gases originating from fresh magma, was estimated, by the spatial
distribution of the variation rate, to be at a depth of 500 m near the 1991-93 eruptive
vents. Finally, significant changes, ranging from 2 to 7 nT, in the local magnetic field
closely related to the main phases of the 2001 eruption were observed. Piezomagnetic
models were used to calculate the expected geo-magnetic changes for each volcanic
process. Model parameters were based on estimated fault geometry using seismic and
ground deformation data from each event.
Description:
Published
Description:
241-262
Description:
1.6. Osservazioni di geomagnetismo
Description:
reserved
Keywords:
magnetic field monitoring
;
Etna
;
04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
book chapter
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