Magma Convective Recharge In Volcanic Systems

Aderson, Samantha J. N. (2004). Magma Convective Recharge In Volcanic Systems. MPhil thesis The Open University.

DOI: https://doi.org/10.21954/ou.ro.0000f593

Abstract

Active lava lakes are not a common phenomenon. Some, such as those found on Kilauea and Erta ‘Ale, have stayed active for decades. Remote sensing investigations (Harris et al., 1999; Allard, 1997; Francis et al., 1993) have measured the volatile fluxes from the lava lakes and found that their fluxes were persistently high. Several suggestions have been put forward to explain this. One explanation is that there are large volatile-rich magma bodies at a shallow depth steadily releasing the volatiles. Studies using other geophysical methods such as gravity and seismics have generally not found these bodies (Francis et al., 1993; Allard, 1997). Another suggestion is that volatile-rich magma is constantly being brought up to the surface convectively and when the volatiles have been released the cooler, denser magma sinks allowing replenishment with fresh magma. This is a possible explanation of the longevity of this volcanic feature, but it is not only lava lakes that appear to exhibit this behaviour. There are dykes in places such as Mount Etna that have remained active much longer than expected.

This study will examine this process using contrasting modelling techniques. The first technique involves finite element models to investigate the factors controlling cooling in dykes. The second technique involves using the results of mathematical modelling to design an analogue model in order to study heat distribution within a lava lake - conduit - magma chamber system.