quote:A peak of activity occurred yesterday, with two strong explosions that produced ash plums that rose to 17,000 ft / 5 km altitude.
The activity was followed by continues, noisy smaller explosions and ash venting which lasted and slowly decreased during the night.
Today, two normal-sized explosions have taken place so far
After a very busy 17 May, with several strong explosions sending ash plumes to up to 16,000 ft (4.5 km) altitude, the volcano has been relatively calm during 18 and most of 19 May.
A filming team of VolcanoDiscovery being on location, we could observe hour-long phases of near-continuous mild to moderate ash venting. After approx. 10 hours of almost no visible activity, a probably strong explosion occurred yesterday night at around 11 pm, lasting several minutes, producing numerous lightning and heavy ash fall on the eastern sector. Cloud cover prevented detailed observations.
quote:The most recent radar measurements done by ALOS-2 satellite of the Japan Aerospace Exploration Agency (JAXA) show that the summit of the volcano has inflated by the enormous amount of approx. 16 cm during the interval 4 Jan - 17 August this year.
This suggests that a significant batch of new magma is currently stored in the volcano's upper plumbing system and the question remains when and how it might erupt. While surface activity at the volcano has remained very calm, authorities continue to prepare for the possible scenario of a major eruption in the near future. [less]
http://www.volcanodiscovery.com/sakurajima/news.htmlquote:Activity has actually decreased and been relatively low at the volcano during the past days. However, the risk of a major eruption remains according to the Japan Meteorological Agency who maintains alert level 4 (preparation for evacuation).
quote:Update
A pancake-shaped flat dome of lava has been detected inside the Showa summit crater. This type of dome is typical for moderately viscous and gas-poor lava (typically andesitic composition) extruded at subduction-zone stratovolcanoes.
The alert level of the volcano remains at 4 out of 5. One possibility is that the dome corresponds to older lava from the upper conduit that has been pushed out by a rising batch of fresher lava still inside the volcano.
Volcanic gas releases from sea floor detected
More worrying signs of volcanic unrest started to appear: according to FNN News, volcanic gas releases have been detected at the sea floor of the Futatsumata Port on the northern shore of Sakurajima peninsula (located approx 4 km from summit).
quote:Vent of Showa crater blocked - internal pressure rising
According to Japanese scientists, the scenario of a major eruption at the volcano is becoming more and more likely. The Asahi Shimbun news agency sent a drone to photograph the crater, confirming that a flat dome is currently blocking the conduit.
This blockage explains the near absence of explosions since mid July and suggests that internal pressure is increasing. The question is, simply put, when will it blow up and how much will come out?
Source: Blocked vent on Kagoshima volcano increasing likelihood of massive eruption (Asahi Shimbu
quote:Alert level lowered, no more deformation detected during 2 weeks
The alert level was downgraded back to 3 (out of 5) last Tuesday as signs of unrest and the risk of a sudden major explosion have decreased.
No rapid crustal movements have been detected since 17 August, suggesting that the inferred magma intrusion has stopped and is now stagnating & cooling instead of migrating further towards the surface.
The volcano continues to be unusually calm with only minor explosions and ash emissions occurring occasionally from the Showa crater.
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