Physical Parameters Define Styles and Transitions of Explosive Activity During the 2021 Cumbra Vieja Eruption
Abstract
The explosive activity of the 2021 Cumbre Vieja eruption (La Palma, Canary Islands, Spain) included lava fountaining, Strombolian explosions, rapid Strombolian, spattering, ash-rich and ash-poor jets, and ash venting, occurring both alternately and simultaneously at multiple vents. To parameterize the defining features and the underlying processes of these styles and their transitions, between 22 September-1 October and between 5-9 November 2021, we deployed one high-speed camera (frame rate 250 to 500 frames per second (FPS) and 0.021-0.147 m/pixel resolution at the vent), one thermal camera (up to 50 FPS and 0.2-0.8 m/pixel .ca), three high-definition cameras (25 FPS, 0.03-1.2 m/pixel ca.), and one microphone (flat response between 0.5 and 10000 Hz, sampling rate 20 kHz). Video processing results by manual tracking and Optical Flow routines reveal pyroclast ejection velocities in the 20-220 m/s range, the highest and the lowest peak velocities pertaining to Strombolian explosions and ash venting, respectively. All styles display ejection velocity fluctuations and variably marked ejection pulses, associated with more or less pronounced acoustic transients. Lava fountains feature the highest mean ejection velocity and a variety of fluctuation patterns, with larger-amplitude and more abrupt ones when transitioning towards Strombolian explosions. The eruption rate of the coarse lapilli to bomb-sized pyroclasts ranges from >2x10^4 to < 2x10^2 kg/s from fountaining to ash-poor jets, respectively, while the in-flight grain size distribution of pyroclasts in the same size range is coarsest during the spattering activity and finer during the ash-poor jetting.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2022
- Bibcode:
- 2022AGUFM.V52C0011S