In Etna, the period from 20 to 26 January was marked by the strombolian and effusive intra-crater activity of the Voragine crater (VOR) and the ash emissions from the new south-east crater (NSEC) and the crater northeast (NEC).
At the seismicity level, a modest seismic fracturing activity is reported, as is the status quo of the volcanic tremor parameters.
The infrasound activity is sustained, the sources of the infrasound events mainly concerning the zone of the northeast crater and, to a lesser extent, Voragine.
The GPS and tiltmeters do not show significant variations, and the fluxes of sulfur dioxide and hydrochloric acid are at a low-medium level. The carbon dioxide values at ground level are low to medium.
Activity at the various summit craters of Mount Etna on 20.25 and 30.01.2020 (from top to bottom) - Sentinel-2 L1C bands 12,11.8A images - one click to enlarge
Intracratric eruptive activity continued in Voragina during the period from January 20 to 26, with Strombolian explosions and the emission of a lava flow, which rises on the south side of the intracratric cone, with spill in the adjacent Bocca Nuova. By the end of the week, lava had completely filled the eastern well of the Bocca Nuova (BN-2). During the week, an increase in the frequency of Strombolian explosions is observed, which led to rapid growth of the cone, especially in its northern part.
Strombolian activity continues on January 30.
Etna - View from the south-eastern edge of Bocca Nuova towards Voragine (VOR), with the lava flow to BN-2 and the cone in growth (upper right corner) - photo 24,01,2020 / Vincenzo Greco / INGVvulcani
Etna - Strombolian explosions on its Voragine crater (one of the four summit craters of the volcano). Photo taken at dawn on January 30, 2020 (view from the south) by Boris Behncke
On January 21 and 22, the New Southeast Crater (NSEC) produced several episodes of modest ash emissions by mouth which opened on December 11, 2019 on the side of the "saddle cone". After January 22, NSEC ash emissions have decreased significantly.
Finally, the northeast crater was the site of discontinuous intracratric and strombolian activity, with periodic emissions of very diluted ash.
Source: INGVvulcani and INGV OE
Nevados de Chillan - plume of ash and gas from 30.01.2020 / 13h56 loc. - photo Pablo Esquivels Twitter
The activity of Nevados de Chillan on January 30 was characterized by 4 seismic episodes.
Volcano-tectonic earthquakes are reported at 3:12 local, 1.9 km from the Nicanor crater, and at 8:10 local, 2.5 km from the Nicanor crater. These earthquakes, associated with rock fracturing, occurred without changes in surface activity related to the seismic episode.
At 1:56 p.m. local time, an explosion was accompanied by a plume of gas and ash about 3,400 meters above the active crater, the highest in the eruptive cycle of the last four years, and associated with a low-energy LP earthquake.
Another VT earthquake is recorded at 3:45 p.m. local 2.1 km from Nicanor.
The activity remains under the Naranja alert.
A moderate eruptive activity marks the Klyuchevskoy in Kamchatka.
This January 31, the KVERT reports an ash plume at 5,000-5,500 meters asl., extending over 70 km east of the volcano.
The aviation code remains orange, other ash explosions are likely to occur at any time, and affect air traffic.
In Costa Rica, after an increase in seismic activity since Monday, Rincon de La Vieja was the site of a phreatic eruption on January 30 at 12:13 pm; it was accompanied by pyroclastic souls and warm lahars in the Quebradas azufrada and Zanjona, and the rio Pénjamo. The lahars arrived at the bridges between 15 and 30 minutes after the eruption.
Rincon de La Vieja - phreatic eruption of 30.01.2020 seen from the El Palenque finca - photo Teresa Ziniga via Ovsicori
The last phreatic eruption was recorded on January 2 at 11:18 p.m. The increasing seismicity is characterized by the amplified background tremor, the frequency of short tremors which has intensified with several swarms. Two earthquakes of the tornillo type, with a signature of the hydrothermal system, were recorded.
The activity level of the volcano is raised to 3 since the possibility of eruptions has considerably increased.
It is recommended that people do not carry out activities in these drains and remain attentive to secondary lahars.
Source: Red Sismologica Nacional & Ovsicori