MeMoVolc report on classification and dynamics of volcanic explosive eruptions

Classifications of volcanic eruptions were first introduced
in the early twentieth century mostly based on qualitative
observations of eruptive activity, and over time, they
have gradually been developed to incorporate more quantitative
descriptions of the eruptive products from both deposits and observations of active volcanoes. Progress in physical
volcanology, and increased capability in monitoring, measuring
and modelling of explosive eruptions, has highlighted
shortcomings in the way we classify eruptions and triggered
a debate around the need for eruption classification and the advantages and disadvantages of existing classification
schemes. Here, we (i) review and assess existing classification
schemes, focussing on subaerial eruptions; (ii) summarize the
fundamental processes that drive and parameters that characterize
explosive volcanism; (iii) identify and prioritize the
main research that will improve the understanding, characterization
and classification of volcanic eruptions and (iv) provide
a roadmap for producing a rational and comprehensive
classification scheme. In particular, classification schemes
need to be objective-driven and simple enough to permit scientific
exchange and promote transfer of knowledge beyond
the scientific community. Schemes should be comprehensive
and encompass a variety of products, eruptive styles and processes,
including for example, lava flows, pyroclastic density
currents, gas emissions and cinder cone or caldera formation.
Open questions, processes and parameters that need to be
addressed and better characterized in order to develop more
comprehensive classification schemes and to advance our understanding
of volcanic eruptions include conduit processes
and dynamics, abrupt transitions in eruption regime, unsteadiness,
eruption energy and energy balance.