FVXX20 at 07:16 UTC, 15/08/18 from KNES [less]

FVXX24 at 01:21 UTC, 10/01/18 from KNES [less]

In a report posted the next day OVSICORI-UNA noted that seismicity was characterized by low-frequency events, volcano-tectonic events, and tremor with intensifying amplitude; the seismic patterns were similar to those that preceded the phreatomagmatic events on 23 May and 11 June, though the recent seismicity was not as energetic.
(Source: Smithsonian / USGS Weekly Volcanic Activity Report 14-20 June 2017) [less]

The activity at the volcano had started to increase already in 2015. Volcanologists have found evidence of several similar explosions that occurred in the past months, but the most recent one on Wednesday seems to have been significantly larger (although still small in itself).
The most interesting news, however, comes from the analysis of the ejected ash. OVSICORI-UNA staff found that besides fragmented older rocks and sulfur, about 3-10 % of the ejected ash particles are glassy shards from juvenile (i.e. new) magma. [less]

Park rangers have also observed that the volcano is currently having some increased activity: strong bubbling at the lake and floating sulfur rafts on the surface. The water temperature has increased significantly by 15 deg C., compared to measurements made in 2013.
The main hazard from the volcano at present would be hot, acid mud flows (lahars) if larger explosions cause the lake to drain or eject larger quantities of water. Such lahars could affect all sides of the volcano, but the areas to the NE around the Azul and Pénjamo river beds would be most at risk. During previous eruptions such in 1995, they had been affected by lahars already. [less]

The seismic records showed no signals associated with a phreatic eruption or sudden gas output. Cloud cover prevented views of the active crater during an overflight later that day, however clear views of the N and S flanks and areas SW showed no changes. [less]

On September 20 RSN staff made a visit to the active crater of Rincon de la Vieja Volcano, during which they collected a sample of lake water for subsequent chemical analysis and captured thermal images and videos, both of the surface of the lake and fumaroles, and compared them with images taken in April of 2012. This revealed that there has been an increase in the temperature of the lake, while the fumarolic field remained the same. [less]

On 23 February, residents in Guachipelin (11 km to the SW) woke up to hear explosion sounds between 0400 and 0430 local time. Seismic recordings showed signals typical for explosions at the same time, although other residents in other areas did not hear any eruption.
Similar seismic signals were detected on 19 Feb at 00:16 and on 20 Feb at 00:46 local time, suggesting that smaller explosions occurred then as well. [less]