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Explosion at Tungurahua (Image: EDUfoto / Facebook.com/edufoto.org)
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March 10, 2016 - EARTH - The following constitutes the new activity, unrest and ongoing reports of volcanoes across the globe.
Tungurahua (Ecuador): The activity of the volcano has strongly increased since last weekend - a new surge of magma has been arriving at the summit vent and is producing a violent eruption from the summit crater. Its climax so far occurred this morning, at 07:51 local time, when a powerful explosion generated an eruption column that rose approx. 6 km above the crater and reached an altitude of estimated 36,000 ft (11 km). Pyroclastic flows (generated by partial column collapse) descended over 2000 m towards the Mandur and Achupashal areas.
Similar explosive activity, with increasing tendency, had already been occurring during the previous days, in particular since Sunday. Very strong explosions also occurred yesterday afternoon at 16:28 local time, two around noon (also yesterday), as well as at 19:35 and 05:35 local time on Sunday (March 6). All of them produced pyroclastic flows into various directions towards the western (Romero and Achupashal) and northern sectors (Mandur).
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| Steam and ash plume rising 3-4 km above Tunguarhua on March 5. (Image: OVT-IGEPN) |
Violent shock waves that rattled windows and doors and ground rumblings accompanied the explosions and most of the time, a steam and ash column was rising 3-4 km from the volcano. At night, explosions could be seen ejecting incandescent material to great height (many 100 meters) and distances over the volcano's cone, generating spectacular avalanches.
Considerable ash fall has been affecting various areas around the volcano. In particular, the western sectors have suffered most. A team of IGEPN scientists measured a load of 7700 g/m2 of ash had accumulated since the end of February in the areas of Manzano and Choglontus. The area is rich in corn fields which have been severely damaged by the ongoing eruption.
On March 9, activity remained very elevated at the volcano. During yesterday and the night, several more explosions occurred ejecting incandescent material that produced glowing avalanches of up to 1500 length mainly on the western and northwestern flanks.
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Strong explosion from Tungurahua; a small pyroclastic flow can be seen departing from the base of
the eruption column.
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The ash plume continues to reach up to 30-32,000 ft (9-10 km) altitude and drifts SSE, Washington VAAC reports.
Nevado del Ruiz (Colombia): A series of small explosions occurred at the volcano yesterday. The first happened in the afternoon at 16:32 local time.
The Manizales volcano observatory recorded a pulse in tremor and reported an ash plume that rose 1300 m above the summit.
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| Eruption of Nevado del Ruiz |
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| Another small explosion |
Similar explosions with ash emissions could be seen on webcam images at 18:15 and 18:40 (local time), before night obscured the view. No incandescence is visible from the crater.
Light ash fall probably occurred in areas to the SW belonging to the departments of Quindío, Risaralda and Caldas.
Sangay (Ecuador): The Geophysical Institute (IGEPN) reported an increase in activity from the volcano since March 5, when volcanic earthquakes started to become more frequent in number.
Between 8 and 9 March, this activity picked up significantly and signs of small explosions (11 in total since March 7th) as well as small episodes of tremor appeared. This probably means that new magma has arrived to produce strombolian activity in the summit crater. A thermal anomaly visible on satellite data fits this interpretation well.
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| Sangay's seismicity of the SAGA station since 4 Mar 2016 (IGEPN |
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Explosions and seismicity at Sangay since March (IGEPN)
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Sangay is one of the country's most active volcanoes, but thanks to its very remote location on the southeast side of the Cordillera Real it is rarely visited and directly observed. However, there is evidence that it has been in semi-permanent activity since at least 1628.
The last eruptive phase of the volcano had begun in January 2015 and lasted until mid April 2015. It produced two small lava flows that reached a few hundred meters below the central crater and moderately large ash plumes. No inhabited areas were affected (there are none very close either).
Typical eruptive episodes (one of which has just started, it seems) consists of strombolian activity, emission of lava flows, and - when activity becomes more intense - pyroclastic flows and larger explosions that produce ash plumes.
IGEPN recommends not to ascend the volcano at the moment.
Sinabung (Sumatra, Indonesia): Explosions and generally small pyroclastic flows, sometimes happening together, continue to occur at the volcano at rates of a few per day on average.
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Explosion and pyroclastic flow at Sinabung yesterday evening (Photo: Leopold Kennedy Adam @LeopoldAdam / Twitter)
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Yesterday evening 17:55 local time, an explosion produced a plume that rose 2.3 km and a pyroclastic flow that traveled 1.5 km.
Dukono (Halmahera): Strong ash emissions continue to be reported from the volcano. Yesterday, a plume stretched almost 100 km to the NW.
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Dukono's ash plume over northern Halmahera seen on NASA's Terra satellite on March 7, 2016
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Lokon-Empung (North Sulawesi, Indonesia): A warning was issued for the volcano and its alert level raised to 3 ("siaga" - alert, on a scale of 1-4) last Monday after a seismic swarm was detected to occur under the edifice.
The previous day (7 Mar), PVMBG recorded 25 deep and 138 shallow volcanic quakes, 23 rockfall signals as well as a tremor signal. In addition, deformation (inflation) was measured to occur under the Tompaluan crater.
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Earthquake swarm at Lokon volcano on March 8, 2016 (VSI)
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Seismicity at Lokon during the past weeks (VSI)
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While no to little changes were seen in surface activity (degassing), these geophysical parameters seem to suggest that internal pressure in the hydrothermal system of the volcano has recently increased and the risk of sudden explosions (phreatic or phreatomagmatic) has to be considered elevated at the moment.
Visitors and locals are advised not to approach the crater within a radius of 2.5 km.
Kilauea (Hawai'i): No significant changes in the ongoing eruption of Kilauea have occurred since the last update.
The lava lake at the summit caldera has dropped again and was about 33 m (108 ft) below the rim of the Overlook crater yesterday.
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View of Puu Oo on March 4th. (HVO)
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On the eastern rift zone, the recently active lava flows inside Puʻu ʻŌʻō crater were now inactive. Lava originating from the vent continues to flow into tubes, feeding scattered surface lava flows on the slowly growing "June 27th" lava field. All active breakouts remain within 6-7 km distance and far from any nearby communities.
Santiaguito (Guatemala): Activity at the Caliente lava dome continues to be high. Another moderately strong explosion occurred yesterday morning, causing a part of the Caliente lava dome to collapse and form pyroclastic flows on its north-northeastern flank.
According to a bulletin of the INSIVUMEH volcano observatory, an ash column rose to 4,000 m altitude and produced light ash fall in areas to the NNE including Quetzaltenango and Santa Marcos Palajunoj.
Suwanose-jima (Ryukyu Islands): The eruptive activity at the remote Island in southern Japan continues. It even seems to have picked up in intensity, judging from the increasingly frequent volcanic ash reports issued by Tokyo VAAC and the sometimes very strong glow visible from neighboring islands.
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| Eruption from Suwanose-Jima. |
The exact type of activity in the Otake crater is unknown, but likely consists of strong, ash-rich strombolian explosions.
Makian (Halmahera): The alert level of Makian Island's Kie Besi volcano was raised from 1 (normal) to 2 ("waspada" = watch) yesterday, as an increase in seismic activity has been detected recently under the volcano.
The stratovolcano, which forms a small island south of Ternate (and is in the center line of tomorrow's Solar Eclipse, where one of our groups is currently stationed...), is one of the regions most active (and dangerous) volcanoes with a number of strong explosive eruptions in historic times, last in 1988.
Already on 2 June 2009, a similar increase in internal activity had triggered a raise in alert level, but unrest declined soon after again and the volcano was placed back to normal again on 16 July, as no further changes in activity had been detected.
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| Seismic activity of Kie Besi volcano (Makian) over the past weeks (VSI) |
The current, most recent phase of unrest began apparently last year. A series of deep earthquakes could be felt in the region in November. Since January, the observatory noted an increase in the number and size of shallow volcanic earthquakes. Weakly felt quakes occurred on 12 January, as well as on 18 and 24 February. Long-period quakes and volcanic tremor (regular vibrations), both related to internal fluid movements also started to occur since the end of past February.
The volcano's seismic activity further increased during the past week and now volcanic tremor has been a weak, but constant signal since 7 March which is why the volcano's alert level was now raised.
So far, no signs of changes in the volcano's visible (surface) activity have been noted, in particular concerning the relatively weak fumarolic activity in the summit crater. However, volcanologists interpret the increased seismic activity and its characteristics as likely created by a magma intrusion from depth, and that fluids, possibly magma, have been moving closer to the surface, causing an increase in internal pressure, and, hence the risk of sudden explosions.
For now, no evacuations are recommended, but the local population is advised to stay alert of possible tremors that can be felt. It is apparently not expected that an eruption might occur in the near future, but increased vigilance is in place as things can change quickly at active volcanoes. Past eruptions of Makian have often produced pyroclastic flows and significant ballistic ejections that pose great risk to nearby areas, especially within a radius of 2 km.
For the time being, the local population on Makian island around G. Kie Besi volcano and visitors / tourists are advised not to climb the crater and remain outside a radius of 1.5 km from gunung Kie Besi's summit crater.
Momotombo (Nicaragua): The eruption of the volcano continues with little visible changes: Intermittent vulcanian-type explosions of mostly small, but sometimes moderate size continue to occur at rates of 1-2 per day (on average), the stronger ones showering the upper flanks of the cone with incandescent material and producing ash plumes that rise 1-2 km above the summit.
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| A spectacular explosion at Momotombo. |
In addition, weaker activity of semi-persistent style also occurs. Continuous glow is visible from the crater at night. This is probably due to the presence of a small lava lake or (more likely) a small lava dome (more viscous lava), as well as frequent, but small (strombolian-type) explosions (that don't reach the outer rim) as INETER reported in its recent status update (53 explosions recorded during March 3-4).
According to Nicaraguan scientists, seismic activity of the volcano has been at low to medium levels.
Nyiragongo (DR Congo): Some very unusual and alarming events have been taking place at the volcano recently: A new eruptive vent opened at the northeastern end of the lowest crater terrace, outside the active lava lake (which had been in place since 2002) and just beneath the near vertical crater walls..
According to a preliminary report of the Goma Volcano Observatory (GVO) who visited the volcano during 1-2 March, the new vent is now forming a second lava lake. Images from a visit of GVO staff show a spatter cone erupting fresh lava flows that pooled onto the crater floor.
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| View of the crater of Nyiragongo on March 1 or 2, with the lava lake and the new vent at the NE margin of the crater floor (Image: OVG) |
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The new vent on the NE end of the crater floor on 1 or 2 March 1 or 2. (OVG)
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GVO reported that since the end of February, activity at the volcano has been more intense than usual. In particular, starting from 04 am on 29 February, local inhabitants began to hear frequent rumblings coming from the volcano almost every minute. Likely, these were caused by the opening of the new dike (fracture occupied as pathway for the new magma) and associated rockfalls inside the crater (the vent is directly located near almost vertical walls). It is important to note as GVO's report mentions, that the location of the new vent is on the east-trending fracture zone that connects the summit vent of Nyiragongo with the prominent flank cone Baruta to the northeast of the main edifice, near the village of Kibumba.
This rift zone (along with the southern rift zone extending towards Goma town) is one of the most prone locations of the volcano's dangerous flank eruptions.
Hiked to #Nyiragongo this weekend. Largest lava lake in the world, activity increasing. #hike #so2 #goma pic.twitter.com/Bm9hPiyGts— langley dewitt (@langleydew) March 8, 2016
When these occur, the volcano's edifice is ruptured laterally, allowing magma to drain outside. Such eruptions have been occurring at intervals of few decades typically. They usually drain very large volumes of very fluid, and hence, unusually fast flowing lava from the lake in short time. The results of the past two such eruptions in 1977 and 2002 were catastrophic: they killed more than 1000 people, destroyed dozends of villages and a large part of Goma town (in 2002).
Whether or not the current developments are precursor of a new eruption from Nyiragongo's flanks is difficult to say, but the appearance of the new vent tells that an extensional movement has taken place on this fracture zone, something that is certainly alarming.
- Volcano Discovery.
