El Hierro Island eruption 2011-12 - updates part 2 Dec-March 2012Click here to go to the latest reports
Update Tue 28 Feb 10:06The eruption goes on at minimal intensity. No or only minimal tremor signal and a few weak earthquakes suggest that the eruption is not yet fully over and that there is a low chance it could restart. At the sea, almost no stained area of upwelling water can be recognized.
Volcanic tremor has stopped, but jacuzzi still visible
Update Sun 26 Feb 08:52
Activity at the water surface returns
Update Thu 23 Feb 19:42
The research vessel Ramon Margalef and other ships have started a new bathymetry mission, which hopefully will result in a detailed mapping of the new submarine topography of the area of the vent.
Almost no tremor and no visible activity, but earthquakes continue
Update Tue 21 Feb 17:33
The only sign that the eruption is not yet completely over is the continuing earthquake activity (with 35 events recorded over the past 3 days), concentrated at 10-15 km depth in the western sector (see graphic), which could suggest ongoing magma intrusions at that depth.
Update Thu 16 Feb 23:21The eruption is still pausing, but about 30 mostly very small earthquakes occurred today. Not much visible activity, and tremor is at minimal levels.
Eruption (almost) stopped - the long ending of an eruption
Update Thu 16 Feb 10:24The eruption has once again paused or perhaps even stopped. There is no longer any significant tremor signal and only a very weak stain can be seen on the ocean. Small earthquakes continue, however, suggesting that it is probably once again only a pause in the eruption. On the other hand, the clear trend of decreasing overall activity over the past 3 months is continuing as if the eruption ends with a very long decreasing tail.
New bathymetric map published - top of the volcano at 120 m depth, secondary cone at 200 m depth
Update Thu 16 Feb 01:15
The most interesting finding is perhaps that the submarine edifice, which sits on the steeply descending floor of a submarine canyon, and is about 100-150 m tall, has not grown significantly in height over the past weeks and there is a secondary prominent vent that has accumulated enough lava to form a small flank cone about 80 m tall and peaking at 200 m depth. The depth of the principal vent is still at about 120 m below sea level.
If current eruption rates continue, it seems extremely unlikely that the eruption, within a foreseeable time, is able to breach the surface to produce Surtseyan explosions or even form a new island.
Whether magma-water explosions can breach the surface depend on mainly 2 factors: the water depth, i.e. containing water pressure, and the flux of magma. Both parameters are probably long outside the range to produce significant explosions visible at the surface.
Source: www.ieo.es/prensa/NP_150212_bimbache10.pdf ("El cono volcánico de El Hierro se encuentra a unos 120 metros de profundidad", IEO press release)
Visible activity ceases, but small earthquakes increase in numbers
Update Thu 16 Feb 00:47The submarine eruption south of El Hierro Island could be in a process of change: While visible activity on the sea surface above the vent, as well as harmonic tremor signal (thought to be more or less proportional to erupting magma flux) have nearly ceased, the number of earthquakes under the island has increased sharply since yesterday.
On 15 February, more than 20 quakes were measured. Most of the earthquakes were very small, well below magnitude 2, and were clustered beneath the NW and SW sectors of the island at depths of around 10 km.
Update Tue 14 Feb 08:50The Guardia Civil's video from their last overflight showing the vent area near La Restinga. More videos at: http://www.youtube.com/user/INVOLCAN?feature=watch>
A total of 10 earthquakes (allo well below magnitude 2) were measured yesterday, most of them at around 10 km depth beneath the southern rift zone.
Update Mon 13 Feb 17:25No significant changed to report: the discolored stain and jacuzzi of upwelling water above the submarine vent area has been generally weaker, but is still well visible. Volcanic tremor continues at low levels indicating that lava continues to be erupted. Few earthquakes (3-4 per day, typically) occur beneath the southern rift zone and in the El El Golfo area.
Strong active jacuzzi above submarine vent
Update Thu 09 Feb 16:59
Currents have brought the stained water into the harbor of La Restinga.
Harmonic tremor is maintaining a constant, but very low signal.
Eruption continues at low levels
Update Tue 07 Feb 23:20
The tremor signal fluctuates between periods of low and medium intensity with episodes of bursts, probably corresponding to deep-water magma-steam explosions. Few earthquakes continue to occur, mostly of small magnitude and concentrated in the SW sector of the island.
Update Fri 03 Feb 11:35A large stain with muddy water in the center and occasional lava balloons floating to the surface is visible above the vent.
Tremor at fluctuating low levels, but ongoing. The eruption continues.
Eruption continues, new models of underwater topography and location of vents
Update Mon 30 Jan 18:53
INVOLCAN measured an increase in diffuse CO2 emission from the island in the past 2 weeks, reaching now almost 1000 tons/day (compared to a normal average value of 345, and the peak in November at 2500 tons/day).
AVCAN posted a great article about what is known or can be reasonably speculated about the submarine topography, the location of the submarine vents, and the shape of the new volcanic cone.
Bathymetric comparisons show that part of the northern wall of the canyon, next to the new cone, must have collapsed between late October and mid Nov 2011. 2 principal vents seem to be active at the summit of the cone itself, but due to its position on an inclined slope, much of the erupted material is slumping down into the canyon. This means that growth of the cone towards the surface is a very slow process.
Besides 2 principal emission points, also visible from aerial images of the surface, several other emission points can be identified, and appear to be aligned on 2 or 3 WNW-ESE parallel lines, probably corresponding to eruptive fissures.
Note: this would mean that the eruptive fissure is more or less perpendicular to the SW rift axis, and contrasts the model in figure 6.
Link to INVOLCAN
Eruption continues at low levels
Update Sat 28 Jan 17:35The eruption at El Hierro continues at low levels judging from the harmonic tremor signal which is fluctuating between almost absent and a low signal.
At the surface, smoking lava balloons have been observed rising most of the previous days, indicating that effusion of lava from the vent goes on.
Eruption continues & new bathymetric map published
Update Fri 20 Jan 10:41
In the meanwhile, the long-awaited results of the last bathymetric survey were published. They show that the vent is now at 130 m depth, little more than in November, as most material is needed to build up the sides of the cone. At current rates, the eruption is extremely unlikely to breach the surface anytime soon.
Eruption has paused after an increase in activity today
Update Thu 19 Jan 18:08
About 2 hours ago, all activity has suddenly stopped and only a very weak signal is left. Similar pauses so far have not meant the end of the eruption, rather a temporary blockage of the conduit. The next hours or few days will tell whether and how the eruption continues.
Update Wed 18 Jan 21:34The jacuzzi is strong today and some people report seing smoking lava balloons again.
Eruption picks up again in strength
Update Tue 17 Jan 19:35
Update Mon 16 Jan 12:25
Activity has calmed down but continues
Update Sat 14 Jan 17:30The eruption is continuing, but has calmed down during the past days, with little surface activity at the stained area above the vent. Volcanic tremor is at low, but constant levels.
Update Wed 11 Jan 17:51The eruption is continuing, indicated by constant harmonic tremor. Fewer steaming blocks are arriving at the surface, but that seems not necessarily to be related to the amount of lava output from the vent.
Interestingly, the number of earthquakes has slightly increased recently (2-3 a day, typically). Most of them are now at 13-16 km depth west beneath the southern rift zone, while in almost all earthquakes in the past months were NW of the island. It's possible that magma intrusions are opening new pathways from the magma chamber, believed to be more to the north, towards the site of the current eruption.
Update Tue 10 Jan 10:44
Update Tue 10 Jan 01:07Activity increases and decreases in pulses. On Saturday, many steaming lava blocks with orange flames of burning escaping gasses were been observed. Today, it has been calmer, and no lava blocks appeared, but the stain and bubbling is still very intense. Harmonic tremor continues at low to medium levels, suggesting a constant outflow of lava going on.
As to the hot steaming lava blocks, a similar activity near Terceira Island in the Azores, when such blocks were dubbed "lava balloons". A comparison between the 2 eruptions and more explanations have been posted here.
Special Thanks to earthquake-report for bringing up this story!
Update Sun 08 Jan 19:38
Update Sat 07 Jan 11:19The visible activity seems to be increasing above the submarine vent near La Restinga. At night, glow from burning hot gasses escaping floating lava blocks and steaming during the day is near-continuous now.
Increased tremor with hydrothermal explosion signals
Update Fri 06 Jan 12:38
The harmonic tremor has significantly increased and shows signs of underwater steam explosions (the bursts in the signal). A M1.8 earthquake 16 km below the southern rift zone occurred yesterday at 1 am.
Glow not from incandescent lava, but combusting gasses
Update Thu 05 Jan 18:52We were a little to overexcited to see the glow during the night. IGN presented a more plausible explanation: the glow originates not from incandescence of still hot lava (this would need to contain areas with >600 deg C in order to emit red glow) inside the blocks, but from combusting gasses. The reason the blocks (some of which reach a few meters size), rise floating to the surface is that they contain a lot voids in their interior filled with still hot gasses (could be H2 or CO, speculation) that escape and combust at the surface. The blocks then sink back into the water. IGN measured the temperature of these gasses to be larger than 200ºC.
Update Thu 05 Jan 11:39The harmonic tremor has descreased this morning, but is slowly picking up again. You can check it at: IGN volcanic tremor
Glowing lava stones visible at night
Update Thu 05 Jan 11:25
There are now some nice clips on youtube showing this phenomenon. It suggests that the submerged cone is now significantly closer to the surface than it was in late November and December, but there is no way to predict whether and when it might breach at all.
La Restinga, El Hierro 4-5th January Night Smoking Lava Stones (youtube)
Update Wed 04 Jan 18:26
El Hierro submarine eruption continues into 2012
Update Wed 04 Jan 12:06Each time we think that the submarine eruption south of El Hierro is subsiding, it regains strength shortly afterwards. During the past week, and in particular today, steaming lava blocks have again appeared above the submarine vent at the ocean surface, showing lava is still being erupted below. The stain on the surface has been well visible at times, with sometimes bubbly foam rising to create wonderful abstract natural paintings of colors and lines when seen from the air.
The harmonic tremor continues as well. After almost stopping on 28 Dec, it has recovered and maintains itself at moderate to low levels, but indicates that the eruption still continues.
Link to the latest photos taken from the Guardia Civil´s regular overflights: INVOLCAN
Eruption is ending (?)
Update Wed 28 Dec 21:54
No significant earthquakes have been occurring, nor other signs suggesting any significant ongoing activity.
Eruption picks up again?
Update Tue 27 Dec 20:07Since yesterday, the tremor signal, which had almost stopped 10-14 days ago, has picked up intensity, suggesting that volcanic activity and effusion of lava has increased again. Correspondingly, new muddy spots of upwelling water above the submarine vent(s) have been observed today at the ocean surface ca. 1 km south of La Restinga.
Update Wed 14 Dec 22:50Some of us watching the webcam are near-convinced to have seen glowing lava blocks dancing in the waves on the zoomed in El Hierro webcam tonight. This seems surprising, but not impossible and would suggest that the vent has grown further in height. Earthquake-report.com, who collects information from people on El Hierro, favors the more plausibly seeming interpretation that it is a ship, but even people on EL Hierro seem not to be sure about it, which is a bit strange.
Update Tue 13 Dec 08:52No further earthquakes until now.
Tremor has decreased a little bit, but continues with rythmic hydromagmatic bursts with varying intensity.
Jacuzzi seems to be active as judged from webcam.
Update Tue 13 Dec 03:18
Based on earthquake-report.com's reports, the eruption could be causing the formation of (normal, not volcanic) clouds, which could be observed from land and on weather satellite images. While it could be coincidence, increased evaporation above a large surface of slightly warmer sea water in the area above the volcano is likely to favor the formation of clouds.
Submarine eruption shows sign of increased activity: strong tremor with rythmic explosion signals
Update Tue 13 Dec 03:02
The visible stain and "jacuzzi", i.e. rising bubbly and muddy water above the vent area has been more vigorous in the past days, although no reports are available about steaming blocks reaching the surface.
Since Saturday (10 Dec), the harmonic tremor signal from the has almost doubled. In addition, it started to show a rhythmic pattern of strong bursts every 5-10 minutes. The most likely explanation are hydromagmatic explosions (steam explosions under water produced by mixing of magma with sea water) interrupting the otherwise steady outflow of lava, most of which is likely forming sheets of pillow lava.
Recent investigations by the oceanographic ships "Ramon Margalef" and the newly arrived "Cornide Saavedra" der IEO (both Instituto Espanol Oceanografia) suggest that there are probably 3 vents close to each other, located along the submarine fissure, and the summit of the new cone is about 100-150 m below sea level and growing. In an interview with Diario de Avisos, Alpidio Armas, the president of El Hierro, said that the volcano grew 80 meters in the last 2 weeks.
For the first time since July, there have been no earthquakes in a 24 hr period between 9 and 10 Dec, and since then, the only one on 10 Dec and there was only one small event (1.9 magnitude at 18 km depth) early on 12 Dec. The absence of earthquakes together with the presence of continuing tremor suggests that the eruption has now stabilized, not that it is ending. The path of rising magma has found a stable condition, so that there is no more need to break new fractures in the basement rock, which causes earthquakes.
However, there is no way of predicting how long the eruption will last and if it lasts long enough so that the pileup of lava can reach the surface, a difficult process prone to back-sets: the more the new cone grows, the more lava will be needed to increase its width as well, and the more likely the cone can collapse from time to time to adjust.
Steaming lava blocks and larger stain at surface
Update Thu 08 Dec 10:37Since a few days ago, in particular yesterday, steaming lava blocks have again been reaching the surface above the spot of the submarine vent. The stain was larger than during the days before.
Today, tremor has sharply dropped, but seems to pick up again. Steaming hot floating lava blocks are still visible. The eruption continues.
For older updates, go to the El Hierro News page.
Part 2 (Dec 2011-March 2012)