San Miguel (Chaparrastique) volcano (El Salvador): new explosion on 18 June 2016

After several months of calm, explosive activity occurred in the early morning of 18 June 2016, generating small ash plumes and ejecting modest amount of incandescent ejecta around the summit crater.
The volcano's current crisis had started on 13 Dec 2013 when seismic activity increased. This culminated in the isolated, relatively large explosion on 29 Dec. Afterwards, the volcano remained restless afterwards with levels of seismicity up to 22 times higher than background. During 2014 and 2015, only few small explosions occurred, usually accompanied by peaks in seismic activity, similar as yesterday's event.
Since the beginning of 2016, seismicity had returned to almost normal levels and degassing had decreased significantly. However, this changed at the end of May.
SNET's seismometers recorded a very strong increase in tremor, related to circulation of fluids (gasses, water, magma) within the volcanic edifice. This first peak passed without surface activity, but another rise in seismic activity, along with increasing SO2 gas emissions (indicator of fresh magma) began on 13 June and was followed by yesterday's explosion.
Volcanologists also noted a slight inflation (swelling) had taken place on the northern flank of the volcano since August 2015. The trend had reversed during January-March 2016 but then again changed to inflation afterwards. This continues currently.
According to their special reports, volcanologists of SNET believe that these signals could be related to a small magmatic intrusion.

The explosion caused light ash fall in nearby downwind areas, but no significant damage. Since the eruption, the crater continued to show strong degassing, producing a plume that reached 400 m height.