Publication Date:
2017-04-04
Description:
Magma flow during explosive volcanic eruptions has been described assuming rigid conduits with simple
cylindrical or planar geometries. Here we study the dynamics of explosive volcanic flows to take account of
the role of elastic deformation of the conduit influenced by local magmatic pressure. Three cases are
investigated: a dyke with elliptical cross-section, a cylindrical conduit and a deep dyke connected to a
shallow cylinder. The model CPIUC (Macedonio et al., 2005) was used for simulations and generalized to
account for elastic deformations of the conduit cross-section area due to magmatic overpressure.
Fragmentation level is typically deeper in a dyke than in a cylinder. For flows in wide dykes pressure at
the fragmentation depth can be lower than the surrounding lithostatic pressure by several tens of MPa,
indicating that the wall-rocks of the dyke will be unstable, constraining the dyke width and eventually
blocking the eruption. On the other hand, when the fragmentation level is shallow the corresponding
lithostatic pressure is not large enough to close the dyke and eruptions from wide dykes are possible. The
behaviour changes drastically when we assume the conduit is a dyke at depth that evolves to a cylinder near
the surface. In this case even very wide dykes can be stable because the fragmentation level moves into the
cylindrical region where deformation is negligible.
Description:
Published
Description:
455–462
Description:
3.6. Fisica del vulcanismo
Description:
JCR Journal
Description:
reserved
Keywords:
conduit geometry
;
explosive eruption
;
elastic effect
;
dyke deformation
;
04. Solid Earth::04.01. Earth Interior::04.01.99. General or miscellaneous
;
04. Solid Earth::04.04. Geology::04.04.06. Rheology, friction, and structure of fault zones
;
04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
