La Palma volcano update: No new activity - pause of eruption or end?
The calm allowed scientists to actually approach the crater to take gas measurements and film the craters from close:
Un equipo del INVOLCAN accede por primera vez a la boca activa de la erupción para realizar geoquímica de gases, a las 13:00 hora canaria / An INVOLCAN team access for the first time to the main active vent to perform gas geochemistry at 13:00 Canarian time pic.twitter.com/1p4wVdbn0V— INVOLCAN (@involcan) December 15, 2021
Primeras imágenes del interior del cráter más activo donde hay desgasificación, donde uno de nuestros equipos ha conseguido acceder a las 13:00 hora canaria / First footage of the interior of the strongest degassing crater, where one of our teams reached at 13:00 Canarian time pic.twitter.com/kKtnSOdZAa— INVOLCAN (@involcan) December 15, 2021
Is the eruption over?
Whether the eruption has ended or not will depend on whether magma still stored in the reservoir beneath the surface is able to ascend or not, which in turn is likely depending on two main factors:
First, whether the shallow reservoir is being re-supplied by magma from the deeper source, which should become visible with the occurrence of deeper earthquakes - lately, these have been mostly absent, suggesting that supply from the deep source has ended.
Second, the ascent of magma from the shallow reservoir is driven by gasses dissolved in the magma and forming bubbles to increase volume and pressure and eventually make the magma rise to erupt as lava.
If, and this is maybe a likely scenario, most of the gasses have already left the system or if the remaining gasses can separate efficiently from the liquid (magma), and rise and degas at the vents and through the surface, the magma will slowly start cooling down and eventually crystallize over a very long period of time.
It is also very much possible that the current pause of the eruption leads to a blockage of the upper conduits, which disables the degassing process and generates conditions that could lead to sudden explosions and allowing probably smaller batches of remaining magma to erupt in short phases of re-activation.
Nobody knows for now - the situation remains volatile and care should be taken to make any predictions of whether activity will resume or not.