Over the last three weeks we have seen small mud and steam explosions in Whakaari / White Island, New Zealand, looking like geysers in the active ventilation zone.
These have reached a maximum height of about 10 meters. They pose no threat to visitors to the island and are not a sign of increasing volcanic activity. No changes in the parameters monitored outside the expected signals for minor volcanic disturbances, and the level of Whakaari / white island remains at level 1, with a color code aviation: green.
In the course of field measurements, volcanologists have discovered finger-like sulfur formations in the vapors emitted by a vent; they form when a stream of molten sulfur, at 115 ° C or more, cools and solidifies.
Sources: GeoNet / GNS
At Karangetang, on alert 3 / siaga, degassing is observed at a height of 300 meters above the summit, of white color and moderate intensity.
The lava flow of the main crater is observed at a distance of 1000-1500 meters in the western drainages.
Seismicity is characterized on September 25 by 146 earthquakes of eruption, 16 earthquakes of blast, 7 hybrid earthquakes, 3 distant tectonic earthquakes and the tremor of dominant amplitude to 2mm.
In Copahue, since mid-September, LP earthquakes of low energy, in relation with a superficial volcanic activity in the crater, are observed.
This activity is manifested by a continuous degassing, more intensely observed according to the atmospheric conditions, and sometimes charged with ashes, which darken the snow-covered slopes.
Sources: Sernageomin & Valecaviahue / Twitter
The prefecture of Mayotte has issued a warning and safety instructions in case of marine submersion during high tides (with waves around 4 meters) that should impact the island from 28 September to 2 October.
These tides, usual at this time of the year, are worrying because of the subsidence of the island from 9 to 15 cm. following the ongoing seismo-volcanic activity; homes near the coast, roads and part of the runways of the airport may be submerged.
The French authorities have set up a magneto-telluric measurements campaign on Mayotte in order to better understand groundwater fluctuations.
Sources: Prefecture of Mayotte and REVOSIMA