The active crater of Poas the 22.08.2017 / 11h15 top photo / Ovsicori, bottom photo / RSN, the 11.08.2017 with 12h31
The Ovsicori announced on August 22 at 11 am a relatively quiet activity in Poas, with continuous degassing and a plume of water vapor, magmatic gases and aerosols. The mouth B, boca Azufreda, emitted aerosols containing very fine particles of native sulfur. Ovsicori recalls that fine particles of less than 2.5 microns can penetrate the lungs and bloodstream of people and animals and cause serious illness.
The incandescence of the mouth A, boca roja, was maintained, in spite of a diminution of its brilliance.
At 15:17 on the same day, an eruption of ashes and gases was recorded, accompanied by an eruptive column rising 500 meters above the bottom of the crater (3,208 m asl). Ash falls are reported on Esquipulas as well as sulfur odors perceived at Tacares de Grecia.
Sources: Ovsicori & RSN
Evolution of the eruptive plume of Poas respectively at 15h19, 15h22 and 16h03 - one click to enlarge the photos taken by RSN
The Sakurajima presents on the morning of 23 August a strombolian-type activity, with continuous projections several tens of meters high, at the Showa crater.
According to the JMA, between August 10 and 14, 44 eruptive episodes marked the Showa crater, one of which was described as explosive; It was accompanied by an ejection of materials at a height of 500 meters, and a plume rising to 1,800 meters above the crater.
The alert level remains at 3, on a scale of 5.
Eruption of Sakurajima at 2:07 on August 23, 2017
In New Zealand, on White Island, quieter conditions enabled the GNS scientists to get closer to the areas transformed by the explosive eruptions of last year.
The eruption of April 2016 caused a blast so violent that it traveled the main floor of the crater by hiding the tourist access routes, and burying markers laid by scientists.
A new stable crater lake has returned since April 2017, completely "different" from previous lakes. The temperature of the acid lake is only 20 ° C instead of the typical 30 ° C to 70 ° C in the past. Its concentration of volcanic elements is the lowest in 15 years. This new situation results from a lesser input of volcanic and liquid gases into the lake, which is now fueled mainly by precipitation and runoff.
The team also found that the temperature of the gases that escaped from the fumaroles had gone from over 450 ° C, during the 2012 episode, to 330 ° C after the eruptions of 2016, and finally to 114 ° C today.
Since the mid-1970s, a crater 100 meters deep and 300 meters wide has widened during a particularly intense period of 12 years. The latest observations suggest that the level of instability has decreased, and will allow an unreachable data collection, especially with regard to the gases emitted by the active crater.
Source: NewZealand Herald
White Island is only the emerged part of an underwater volcano established in Plenty Bay, and is one of New Zealand's most active volcanoes - photo R. Fleming
At Piton de La Fournaise, the volcanic tremor (an indicator of surface eruptive intensity) remains stable and weak.
Two volcano-tectonic earthquakes of low magnitude were recorded under the southeastern region of the enclosure during the day of 22 August.
No significant distortions have been observed over the last few days.
The often unfavorable meteorological conditions, as well as the low fluxes observed, have not made it possible to make reliable estimates of the flow of lava by the use of satellites.