El Hierro Volcano eruption (Canary Islands) : Part 1 - July 28 until September 7, 2011

Version en Español - Spanish version

This is Part 1 of the  El Hierro Volcano eruption report


Our tweets are also posted into our Facebook Volcano Page
With the collaboration of Joke Volta, an El Hierro resident

Read also : Scientific paper reveals massive historic Tenerife volcano flank collapse
Read also: Economic impact on El Hierro and the Canary Islands if an aerial eruption would occur

Read also
: Part 1 (from July 28 until early September)
Read also: Part 2 (from September 25 until October 10 )
Read also: Part 3 (from October 11 until October 13 )
Read also: Part 4 (from October 14 until October 17 )
Read also: Part 5 (from October 18 until October 21 )
Read also: Part 6 (from October 22 until October 26 )
Read also: Part 7 (from October 27 until October 31 )
Read also: Part 8 (from November 1 until November 3
Read also: Part 9 (from November 4 until November 6
Read also: Part 10 (from November 7 until November 8)
Read also: Part 11 (from November 9 until November 11)
Read also: Part 12 (from November 12 until November 15)
Read also: Part 13 (from November 16 until November 19)
Read also: Part 14 (from November 20 until November 23)
Read also: Part 15 (from November 24 until November 27)

UPDATE 07/09 - 14:26 UTC : Tremor has continued at El Hierro since the start of seismicity in July.  Between the 30th August and 3rd September seismic events were high at ~200 to 250 a day. However, since then there have been less than 100 events a day. GPS stations are now in place around the volcano. On the 24th of August Eruptions Blog and @Teideano reported an uplift of ~1 cm.  There has been no uplift (inflation - to my knowledge) reported recently.
It seems that magma is still moving beneath El Hierro and may continue for a while to come yet. So keep watching.Up to date info is available at Actualidad Volcánica de Canarias.

UPDATE 05/08 - 21:09 : Earthquake events are continuing underneath El Hierro, with the majority of events between 8 and 15 km in depth, and as shallow as 2 km (+/- 0.5) with an average of around 11.5 km.  As of yet, there are still NO other additional signs of an eruption, an increase in gas (which has been detected) or any change to deformation signals.
In a post of the Eruptions blog by Erik Klemetti, the situation at El Hierro is described in detail. For the moment it is still to early to tell what will happen, so keep watching.

Original text
Recently El Hierro volcano of the Canary Islands has been experiencing a seismic swarm beneath it, which as of yesterday reached to over 700 events.

Most of these events have been at Magnitudes of around 2 (+/-0.5) and are clustered beneath El Hierro whilst the depths of these earthquakes have been roughly between 9 and 16 km for the most part, with the exception of a few shallower and deeper quakes, the shallowest of which has been around 4 km (as of 27/04/11 8am GMT for the plotted data below) but as shallow as 1 km following this.
If we look at these earthquakes in two plots here http://www.volcano-blog.com/hierro.html we can see the clustering of these earthquakes is mainly confined to an oval area at 10 km depth.

El Hierro is a broadly basaltic volcano which might have been active in 1793 although this is uncertain.

So the big question is, what's happening here?
It is possible that there is magma on the move at depth, perhaps moving into a magma chamber.
Does this mean that there will be an eruption? Maybe, maybe not.
The majority of magma intrusions do not reach the surface, and as has been seen elsewhere, in the past, activity can cease at anytime.

As of yet (to my knowledge) there have been no other signs of moving magma at the surface such as ground deformation or increased gas emission, although GPS antenna have been set up by officials at the Canary Islands.
For now it is too early to tell what (if anything) will happen, so keep watching.
If you would like to follow these earthquakes in more detail or look at the raw data, visit here .

El Hierro Volcano Information :
The triangular island of Hierro is the SW-most and least studied of the Canary Islands. The massive Hierro shield volcano is truncated by a large NW-facing escarpment formed as a result of gravitational collapse of El Golfo volcano about 130,000 years ago. The steep-sided 1500-m-high scarp towers above a low lava platform bordering 12-km-wide El Golfo Bay, and three other large submarine landslide deposits occur to the SW and SE. Three prominent rifts oriented NW, NE, and south at 120 degree angles form prominent topographic ridges. The subaerial portion of the volcano consists of flat-lying Quaternary basaltic and trachybasaltic lava flows and tuffs capped by numerous young cinder cones and lava flows. Holocene cones and flows are found both on the outer flanks and in the El Golfo depression. Hierro contains the greatest concentration of young vents in the Canary Islands. Uncertainty surrounds the report of an historical eruption in 1793.

El Hierro Information courtesy   volcano.si.edu (Smithsonian Institution)

Twitter user @Teideano has also been giving regular updates on the situation. I have used some of his info in this report.


  1. Tim Clarke says

    Is there a connection between the chambers deep under the ground, 15km or more, between the islands of El Hierro and La Palma?

  2. John Sager says

    Still continuing. ign.es website now has graphs. There appears to be a distinct 14-day periodicity, but the activity peaks coincide approximately with tidal minima (mid-way between full & new moons)

  3. Can anyone tell me if there is any information about what might be going on below La Palma Island. There have been an increase in siesmic activity there according to the IGN charts, tremors which seem to be more like those of volcanic activity rather than tectonic. http://www.01.ign.es/ign/layoutIn/volcaSenalesAyerHoy.do#

    • I live on the Island of La Palma about 4 kms from the most recent erruption in n1973?

      To my knowledge there is no problem and there have been no tremmors at my home. El Hiero is 90 kms away

    • Armand Vervaeck says

      Thank you for letting us know Anthony, there is indeed NO reason (instrumental) to believe that something would happen in La Palma.

  4. Had a dream last night of being on a smallish island which fits the exact description here. There was a small explosion and lava flow out of its volcanic core. Very odd timing.

  5. Brokker says

    There has been more shallow quakes since yesterday. This map shows quakes in the swarm from 0.1km to 5km from yesterday to today.