OVSICORI-UNA reported that periodic phreatic explosions at Rincón de la Vieja continued to be recorded by the seismic network and webcams during 20-26 May; most plumes rose no higher than 500 m above the crater rim.
Some of the events were not visually confirmed by webcams because of weather conditions or darkness.
A small ash eruption at 0537 on 21 May produced a plume that rose 1 km above the crater rim and contained less water vapor than plumes from eruptive events in the past weeks.
Plumes from eruptive events at 1624 on 22 May and 0608 on 24 May rose 1 km above the rim.
An event at 0325 on 25 May was heard by residents to the N but was no visually confirmed due to darkness.
Later that day, in the early evening, an hour-long sequence of eruptions produced gas-and-steam plumes and ejected tephra no higher than the crater rim (except for an event at 1738).
Source: Observatorio Vulcanologico y Sismologico de Costa Rica-Universidad Nacional (OVSICORI-UNA)