Erosive processes by flowing lava are commonly attributed to so-called
thermal erosion. Here, we report the direct observation of a peculiar lava
channel that was formed near the base of a parasitic cone during the 2001
eruption on Mount Etna. Field evidence strongly suggests that models of
thermal erosion cannot explain the formation of this channel.
We put forward the idea that the essential erosion mechanism was abrasive
wear. By applying a simple model from tribology we derive quantitative
predictions for this kind of mechanical erosion. We demonstrate that the
available data agree favorably with our hypothesis. An interesting
conclusion is that erosive processes resembling the wear phenomena in
glacial erosion are possible also in a volcanic environment.