The eruption of Rincón de la Vieja Volcano on May 23rd revealed the proximity of the magmatic material to the surface. This was determined after the analysis made to the material expelled by the volcano in that event. Which descended in the form of lahars by the nearest rivers.
Although the percentage of magmatic material found is insignificant, it is the first time that scientists confirm the suspicion of proximity to the surface.
About 1% of the fragments possibly indicated that it was a phreatomagmatic activity. This was suspected in previous activities, but it was confirmed by this eruption,”
said Geoffroy Avard, volcanologist at the Volcanological and Seismological Observatory of Costa Rica (OVSICORI).
A phreatomagmatic eruption happens when the magmatic material is so close to the surface that when the gases come out, a little molten material comes along.
Javier Pacheco, also an OVSICORI volcanologist, explained that this material is generally positioned in a kind of reservoir within the massif.
It is a volcano that remains active for a long time. There are small quantities that are rising continuously to the surface, to a surface reservoir and therefore there will always be fragments. In the case of this eruption the percentage of material is very low. They were tiny amounts of magma that were in contact with the hydrothermal system,”
said Pacheco.
The volcanologist exemplified that, compared to Turrialba Volcano, the situation is very different, because the percentage of magmatic material that accompanies those eruptions is around 40%.
Guillermo Alvarado, from the National Seismological Network (RSN), stated that no blocks were found on the southern edge of the active crater.
This does not mean the volcano is emanating lava flows,”
concluded Alvarado.