Lava fountain episode at Etna’s New SE crater this afternoon
The New SE crater produced two short-lived weak lava fountaining episodes today, one in the morning during around 9:30-10:30 am local time and one in the afternoon / early evening that started around 17:40 and is in progress at the time of this update.
In both cases, the activity and its evolution followed the same pattern as observed in the past days: after being more or less silent at the end of the previous episode, strombolian activity picks up along with rapidly increasing volcanic tremor signal (internal vibrations corresponding to rising magma). It rapidly increases, typically within an hour or two after beginning, reaching a short phase of sustained lava fountaining from the summit vent at the crater, known as the Saddle vent. However, these recent episodes, if they can be called paroxysms, seem to only generate lava fountains of modest intensity when compared to paroxysms observed earlier in May and during Feb-March this year. This might explain the current frequency of several events occurred per day now, vs typically one paroxysm at intervals of at least 36-40 hours or longer (but much stronger).
Etna (Sicily, Italy): Another intense eruptive phase likely with lava fountains occurred this afternoon, but due to cloud cover, it was not possible to observe it very well visually. Tremor started to rise in the morning, followed by increasing explosions and ash emissions from the New SE crater. It reached high peak values between around 14:40 and 15:15 local time, when the activity likely consisted in sustained lava fountains. Activity dropped sharply afterwards only to pick up again after about 2 hours and is currently again rising, possibly giving way to yet another lava fountain phase in the next hours or so.
Kilauea (Hawai’i): (26 May) Excerpt from the USGS Hawaiian Volcano Observatory’s May 26, 2021 Daily Update: Activity Summary: Kīlauea Volcano is no longer erupting. Observations indicate that the eruption in Halema‘uma‘u at the summit of Kīlauea Volcano has paused. This morning, May 26, the lava lake is 229 m (751 ft) deep and is stagnant across its surface. Within the past 48 hours, no active lava was observed in webcam images of the Halema‘uma‘u crater lava lake surface. Field crews on May 25 did not observe any signs of lava lake activity, and reported no signs of recently active surface lava. Sulfur dioxide emission rates remain slightly elevated. … [read more] … [show less] HVO will issue a Volcano Activity Notice (VAN) lowering the Volcano Alert Level for ground based hazards from WATCH to ADVISORY and the Aviation Color Code from ORANGE to YELLOW. HVO continues to monitor Kīlauea Volcano closely for additional signs of changes in activity. Summit Observations: The most recent sulfur dioxide (SO2) emission rates, measured on May 23, were 100 tonnes per day, continuing a trend of decreased emission rates that began in mid-April. The SO2 emission rates are now nearly at levels associated with the recent non-eruptive period from late 2018 to late 2020 (less than 50 tonnes per day), and are significantly lower than emission rates that averaged over 800 tonnes per day from mid-February to mid-April. Summit tiltmeters recorded slight but continuous deflation over the past 24 hours. Seismicity remains stable, with elevated tremor.
Great Sitkin (United States, Aleutian Islands): After the latest explosive eruption at the volcano yesterday, a seismic activity has decreased gradually although volcanic unrest continues as reported local observatory Alaska Volcano Observatory (AVO). Surface temperatures continue at elevated levels identified in satellite data. … [read more] … [show less] No ash emissions are observed from surveillance cameras. Prognosis for renewed eruptive activity is uncertain. Additional explosive events, effusive eruption, or a return to non-eruptive behaviors are all possible.
Nevados de Chillán (Central Chile): (26 May) Volcanic Ash Advisory Center Buenos Aires (VAAC) issued the following report: UNABLE TO DETECT
Nyiragongo (DRCongo): Authorities are highly concerned about the risk of a second – potentially more destructive if not catastrophic – eruption from the volcano in the near future and have ordered the partial evacuation of Goma, where a mass exodus seems to have started, making the overall situation even more chaotic and difficult. The reason scientists worry are both a lack in precise monitoring data, the potential of large impact of an eruption, and the continuing earthquakes that rattle the area around Goma and Gyseni, as well as ground cracks in and around Goma, which might indicate that magma is accumulating beneath the area and could well lead to a new eruption. … [read more] … [show less] More than 200 tremors have been recorded in the past 2 days. According to some unconfirmed posts on social media, some of the new ground cracks expose glow beneath (likely from hot gasses if true). According to latest findings of researchers, the recent eruption indeed drained the lava lake, but according to some sources, it has already partially refilled (or did not drain entirely).
Current tremor signal showing the peaks of the recent and likely to be soon paroxysms (image: INGV Catania)
Recent earthquakes near Nyiragongo volcano (image: Rwanda Seismic Monitor)
Authorities are highly concerned about the risk of a second – potentially more destructive if not catastrophic – eruption from the volcano in the near future and have ordered the partial evacuation of Goma, where a mass exodus seems to have started, making the overall situation even more chaotic and difficult.
The reason scientists worry are both a lack in precise monitoring data, the potential of large impact of an eruption, and the continuing earthquakes that rattle the area around Goma and Gyseni, as well as ground cracks in and around Goma, which might indicate that magma is accumulating beneath the area and could well lead to a new eruption.
More than 200 tremors have been recorded in the past 2 days. According to some unconfirmed posts on social media, some of the new ground cracks expose glow beneath (likely from hot gasses if true).
According to latest findings of researchers, the recent eruption indeed drained the lava lake, but according to some sources, it has already partially refilled (or did not drain entirely).
Ash plumes are rising from the crater of the volcano, likely from internal collapses after the (partial?) drainage of the lava lake. Combined with the intense degassing activity, they create dangerously contaminated acid rain and people are urged not to use rain water for cooking, washing etc if any possible.
From a summary on reliefweb:
„Researchers observing the volcano have a limited sense of the current risk level; the situation remains highly unpredictable as several warning signs emerge of the risk of a new eruption in the next few days, including multiple cracks on the ground, emission of gas and the worrying fact that the Kivu crater seems to have refilled very quickly, indicating another possible eruption. The IRC is preparing a response to meet the escalating humanitarian needs in collaboration with the government and other NGOs. There is now a desperate need for an increase in funding through support from the international community.“
There are several scenarios how the situation might evolve (adapted from Nyiragongo : de 3 scénarios présentés par l’OVG, une prochaine éruption du volcan est inévitable):
Scenario 1:
A new eruption of Nyiragongo on its southern flank, where fractures open in the area of Goma and Gisenyi cities. Lava flows would likely destroy destroy part of them.
Scenario 2:
An eruption of Nyiragongo volcano on its southern flank, but with fissures INSIDE the city and extending close to Kivu lake. Large volumes of lava destroy part of the cities of Goma and Gisenyi and reaches the lake. The amount of lava that would flow into the lake is insufficient to raise the temperature of the deep water over the entire lake by at least 1° C, there will be no lake overturn and eruption of deadly dissolved CO2 from the gas-rich deep-lake water.
Scenario 3:
An eruption of Nyiragongo volcano opening of fractures on its southern flank inside the city and/or inside the lake Kivu. Parts of Goma and Giseny would be destroyed and the heat released by lava in the lake would trigger an overturn of the deep lake water rich in dissolved CO2. This would cause a catastrophic overturn and sudden release of large quantities of CO2, a so-called limnic eruption. The gas cloud would instantly kill all people and animals at lower elevations around the lake – likely thousands of people.
The same could be triggered if a very large earthquake was to occur under the lake sufficiently disturbing the water layering… While this is the worst scenario, it is hopefully also the least likely.
Scenario 4: No eruption occurs. Seismic activity gradually dies down, as it is a result of internal readjustments after the recent eruption.
Current tremor signal showing the peaks of the recent and likely to be soon paroxysms (image: INGV Catania)
Another intense eruptive phase likely with lava fountains occurred this afternoon, but due to cloud cover, it was not possible to observe it very well visually.
Tremor started to rise in the morning, followed by increasing explosions and ash emissions from the New SE crater. It reached high peak values between around 14:40 and 15:15 local time, when the activity likely consisted in sustained lava fountains. Activity dropped sharply afterwards only to pick up again after about 2 hours and is currently again rising, possibly giving way to yet another lava fountain phase in the next hours or so.
Explosive eruption from Great Sitkin volcano yesterday (image: AVO)
After the latest explosive eruption at the volcano yesterday, a seismic activity has decreased gradually although volcanic unrest continues as reported local observatory Alaska Volcano Observatory (AVO). Surface temperatures continue at elevated levels identified in satellite data. No ash emissions are observed from surveillance cameras. Prognosis for renewed eruptive activity is uncertain. Additional explosive events, effusive eruption, or a return to non-eruptive behaviors are all possible. Source: Alaska Volcano Observatory volcano activity update 27 May 2021
