29 October 2021
The mobility of a rolling volcanic boulder
On this blog I have frequently written about the mobility of boulders once they start rotating on their way down slope. A very beautiful example of this was posted to Twitter yesterday by Harri Geiger. The video was shot on the flanks of the still erupting Cumbre Vieja volcano on La Palma in Spain:
— Harri Geiger (@harrigeiger) October 28, 2021
The video captures a spallation lava bomb. As the video shows, this was a boulder that was roughly spherical, and it was moving on a surface essentially devoid of obstructions and that had, until late in the sequence, a steady slope. The resultant video is a remarkable record of the extreme mobility in these situations.
If the film Raiders of the Lost Ark is ever remade then this video of a high mobility, extremely hot boulder might be food for thought.
Meanwhile, the eruption continues with a great deal of energy. There is no reported evidence of the much-hyped catastrophic flank collapse, and thus of the resultant mega-tsunami, as far as I can see. On 25 October Sotiris Valkaniotis tweeted his latest InSAR analysis of deformation on La Palma:
Cumulative displacement & interferograms from Copernicus #Sentinel1 imagery, for the past month of volcanic activity in #LaPalmaVolcano #Canarias. Descending interferogram has quite decent quality despite of 36d interval. Processed at @Ak_Satellite DAAC HyP3 using GAMMA. 1/2 pic.twitter.com/xbHkoLXRgj
— Sotiris Valkaniotis (@SotisValkan) October 25, 2021
As I’d expect, this shows inevitable inflation and deflation around the vents, but no indication of large scale instability in the flank. La Palma is being monitored closely by multiple groups using multiple sets of tools, so any changes would be rapidly detected.