Bluesky is actually an Umberto Eco chamber, as it tends to warn about the signs of impending fascism and its associated dangers, rather than, you know, to debate and encourage them.

Dewey Finn energy

Thank you!

Feel free to reach out with any questions! Other relevant papers: ❓What happens if we fracture or compact rocks a little bit? doi.org/10.1007/s004...doi.org/10.1002/2016...doi.org/10.5194/se-8...

Fracture and compaction of andesite in a volcanic edifice - Bulletin of Volcanology

The failure mode of lava—dilatant or compactant—depends on the physical attributes of the lava, primarily the porosity and pore size, and the conditions under which it deforms. The failure mode for ed...

Compare the grey signal above with the weird loop-de-loop thing here ... This kind of complex post-failure behaviour—occurring under stress conditions relevant to the dome or shallow 🌋 edifice—could be crucial in regulating heat and mass transfer in volcanoes. Read more: 🔓🔗 doi.org/10.1098/rsos...

There should theoretically exist a zone in porosity–stress space where a rock can *repeatedly* switch deformation style. And lo–one of our samples exemplifies this quirky behaviour. First it compacts, then dilates, then compacts, then dilates, then compacts, then dilates…

In the paper we show C*’, as described above—compaction ➡️ dilation. We also demonstrate the opposite process—dilation to compaction, which we refer to as C’* (C prime star). As far as we know, we are the first to show this formally through experiments. But wait, there’s more!

Turns out, there is, but we had to look in just the right place to find it. If we plot data from Heap et al. 2015 & Farquharson et al. 2016, 2017 as the “inelastic compaction factor” (don’t ask) vs initial porosity, there is an obvious gap. Luckily, we found some samples that fit in there nicely.

Our latest paper (doi.org/10.1098/rsos...) focusses on something slightly different. Just like there are stress/strain conditions that force a rock from compaction➡️dilation, theoretically, there should exist a range of conditions where a rock could switch dilation➡️compaction. (ignore the baboons)

Post-failure deformation mode switching in volcanic rock | Royal Society Open Science

Beyond a threshold applied compressive stress, porous rocks typically undergo either dilatant or compactant inelastic deformation and the response of their physical properties to deformation mode is k...

Compare the two images below, one an as-collected sample of lava from Volcan de Colima, and the 2nd a sample from the same block, but having met C*’. It’s a mess—the groundmass has been smushed into tiny fragments (compaction), but note the fracture through the centre (dilation).