Basaltic volcanism
The
most common, and yet in many ways least studied, type of volcano in continental
settings are relatively small, short-lived volcanoes of mafic composition. We refer to these volcanoes as
monogenetic because they tend to be active for a short period of time
(typically weeks to decades) and then become extinct, i.e., they typically do
not have long periods of repose or dormancy followed by renewed activity as
might happen at a stratovolcano or a caldera. Volumes of individual volcanoes
of this monogenetic type are relatively small (0.001 – 5 cubic
kilometers).
Despite their small size and short lifetimes, these
volcanoes exhibit an amazing range of eruptive processes, from quiet effusion
of lava to sustained explosions that pump ash many kilometers into the
atmosphere. In some cases, changes
in activity can be linked to compositional changes in the erupting magmas,
while in other cases there may be no compositional change to speak of, making
it more difficult to understand why eruption processes can vary so much. A further complication can be the
interaction between lava flows and the construction or destruction of
pyroclastic cones. Understanding
the underlying causes of different eruption dynamics at these volcanoes, by
combining field studies and theoretical fluid dynamics, is a research interest
of mine (see also Pyroclastic
deposits and Volcano
fluid dynamics & modeling).
At a larger scale, monogenetic mafic volcanoes tend to occur
in groups referred to as volcanic fields.
The relationships between eruptive style, volcano location and size,
tectonic structures, petrology, geochemistry, and the long-term behavior of erupted
volume as a function of time, provide key insights into the mechanism for magma
generation at depth and ascent through the lithosphere. There are two end-member types of
basaltic continental fields: (1) at
very low long-term eruptive fluxes, activity is governed by regional tectonic
deformation, while (2) at very high eruptive fluxes, activity is governed by
the thermal structure of the mantle.
I am interested in studying how volcanic fields behave in regimes
between these two end members. All
of this knowledge is important to bring to bear on studies of volcanic risk to
urban areas and facilities that might exist within volcanic fields (see also Volcanic
risk). Additionally, I am interested in the commonalities and
differences between such intraplate volcanic fields in continental and ocean
basin settings.