The 2004–2005 Mt. Etna Compound Lava Flow Field: A Retrospective Analysis by Combining Remote and Field Methods

Mapping lava flows frequently during effusive eruptions provides crucial parameters
to better understand their dynamics, in turn improving our ability to model lava flow behavior. New
photogrammetric methods have recently been developed, shifting the paradigm of photogrammetry
from pure method to a multidisciplinary approach able to reduce the cost of volcanic monitoring and
widen the potential spectrum of application. In this work, we demonstrate how multi-view and singleview
photogrammetry methods can be used effectively to extract accurate quantitative information from
photographs taken during routine surveys over an active lava flow. One intriguing advantage of these
methods is that they can re-use images acquired previously to extract new data from past eruptions. In
particular, we reconstructed quantitatively the evolution of the lava flow field emplaced during 2004–2005
at Mt. Etna, subdivided in five eruptive phases from the earliest simple lava flows to the final compound
lava field about 6 months later. Our results show that, in the first week of eruption, lava field formation
was characterized by an increasing lava length that followed a power law growth and by a decreasing front
velocity that followed a power law as well. Thereafter, the length increasing became almost constant until
the developed lava tube system was able to drain the lava for long distances, with the area inundated by
lava that grew linearly in the first 20 days. Finally, we demonstrate the crucial role that the syn-eruptive
DEMs acquisition could have to improve our understanding of the emplacement dynamics of complex
lava fields.