Mild eruptive activity which started at the New Southeast Crater (NSEC) on July 14 gradually intensified on July 18, INGV reports.
Frequent ash emissions, producing only minor anomalies in images recorded by the thermal surveillance cameras were reported on July 17.
Things changed overnight with Strombolian explosions at a frequency of one every 1-2 minutes early morning July 18 and every 20 - 30 seconds during late forenoon.
The explosions ejected incandescent pyroclastics to a few tens of meters above the vent, which lies in the eastern part of the NSEC. Ejecta frequently fell onto the upper flanks of the cone.
Furthermore, at 05:48 UTC, an emission of ash occurred at the Northeast Crater, which produced a plume that rapidly dissipated in the atmosphere. The first emission was followed by other, smaller emissions that continued at the time of the production of this report [but ceased sometime thereafter].
Differently from the activity at the NSEC, the ash emissions of the Northeast Crater have not produced any anomalous signal in the images recorded by the thermal surveillance cameras.
As for the volcanic tremor, since 20:30 UTC on July 17, a progressive increase in the mean amplitude of the volcanic tremor has been recorded, which rose from low to medium levels. This has been accompanied by migration and superficialization of the volcanic tremor source toward the NSEC area, as well as by an increase in the frequency of infrasonic events.
July 20 update
Featured image credit: INGV