Theoretical Model for Lava Flows in Confining Channels
Abstract
Active lava flows down confining valleys are modelled as Newtonian viscous gravity currents. We determine the structure and the rate of propagation of the flow as functions of the form of the pre-existing topography, the effusion rate at the vent and the effective lava viscosity. When the confining boundary of the flow obeys a power- law with respect to the cross-slope coordinate, and the total volume of fluid obeys a different power-law with respect to time, the extent of the resulting flow can be determined analytically as a function of time for different channel shapes. The channel can be either horizontal or inclined, and its shape can vary gently along the downstream direction. The theoretical results are in excellent agreement with data from laboratory experiments, in which glycerine was released with either a constant volume or flux at one end of a long channel with either a semi-circular or V-shaped cross section. We will summarize the various different propagation rates that arise on different topographies. Applications to interpreting field data will be also presented.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2007
- Bibcode:
- 2007AGUFM.V14A..02T
- Keywords:
-
- 8400 VOLCANOLOGY;
- 8414 Eruption mechanisms and flow emplacement;
- 8425 Effusive volcanism;
- 8429 Lava rheology and morphology;
- 8486 Field relationships (1090;
- 3690)