El Hierro Volcano eruption (Canary Islands) : Part 46 – June 25 and June 26

This is Part 46 of the El Hierro Volcano eruption report

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With the collaboration of Joke Volta, an El Hierro resident and Julio del Castillo Vivero, photographer.
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Update 26/06 - 23:55 UTC
- 224 earthquakes so far today!
-Very strong quakes since just before midnight UTC. People have felt some earthquakes and cant sleep anymore as they are scared for more
The earthquake at 00:11 UTC seems to have been the strongest tonight, but IGN data list is not yet updated
- The image below shows the fierce earthquake and tremor action around midnight.

Update 26/06 - 21:17 UTC
- Earthquakes are continuing but harmonic tremor has decreased.
- Epicenter locations are a little more to the south as explained earlier on. The current edge of the southern quake area is the El Julan coast. A limited number of quakes is below the La Calmas sea very close to the coast.

Update 26/06 - 20:40 UTC - Earthquake number overview
- Sunday : 22 quakes
- Monday 245 quakes
- Tuesday : so far today 194 earthquakes which makes a subtotal since Sunday of 461 earthquakes greater than M1.3

Update 26/06 - 18:42 UTC
- We think that the IGN staff working on El Hierro has been increased significantly as earthquakes are reported much more earlier than before.
- The epicenter name W of El Pinar is suddenly showing more and more in the location lists since 16:13 UTC this afternoon. reason: epicenters have shifted to the south.
- A couple of earthquakes have been located at a depth of 17 km, but the main group remains at 18 to 21 km.
- The image below if from the coastal El Julan area where most of the current earthquakes are taking place. As you can see on the picture, this area of the island is unpopulated. Image was taken by Joke Volta earlier this year.

Update 26/06 - 18:28 UTC
- Harmonic tremor is decreasing a little in amplitude but the quakes are still continuing at a high frequency. IGN has a hard time to list the many recorded quakes.
- So far today, IGN has listed 177 (volcanic) earthquakes!
- We invite people living at El Hierro to describe the shaking experience if an earthquake strikes. We know that most of them are following the Spanish written sites, but Earthquake-Report.com is probably the only or one of the only sites in the world collecting I Have Felt It reports in a structured way. We have literally received thousands of earthquake experience reports in only a couple of months since our system is active. People are also allowed to write in Spanish.
http://earthquake-report.com/2012/06/25/complete-earthquakes-list-june-26-2012/

Update 26/06 - 17:48 UTC
- Joke Volta has felt the quake(s) in El Pinar and has found out that the I Have Felt It form is not working.
- EMSC is listing 2 M3.5 earthquakes, one at 16:35 and another one at 16:50 UTC. The stronger quakes can also be followed in our own site at the following page.

Important update 26/06 - 17:36 UTC
- Harmonic tremor continues to be strong. The strongest earthquakes of the last 90 minutes are currently being added by IGN and are close to M3 or higher.
- The magma flow has migrated more to the El Julan coastline, in other words more direction Las Calmas sea. Reported depths are still the same.
- The current activity clearly generates magma flow into other chambers below the volcano. Nobody knows what the final outcome will be. The only certainty is the the magma pressure is very high since a couple of days.
- To the positive side is that the activity is currently taking place below an unpopulated area of the island and is going again in the direction of the Las Calmas sea

Update 26/06 - 17:29 UTC
- IGN just posted the strongest earthquake so far today, a M3.5 below the El Julan coastline, still at a depth of 19 km (Magnitude and other parameters are preliminary).

Update 26/06 - 17:17 UTC
- By gar the strongest seismic activity has started a little after 16:00 today. As Harmonic tremor is seriously up, the magma may have found a path towards some new areas (not necessarily another part of the island).
As we will be blind for about 2 hours, we will have to wait until IGN is listing the stronger set of earthquakes and activity from the last hour. Follow our updates to find out if a major change is happening.

Update 26/06 - 16:54 UTC
-The NASA-Modis satellite image from earlier today shows the Calima from space. The blue circle indicates Tenerife island. The pictures from Joke Volta below are showing Calima as seen from the island.

Calima from space above El Hierro (blue circle = Tenerife) on June 26 2012 - image courtesy Nasa-Modis-Lance satellite

Update 26/06 - 16:20 UTC

Pevolca press report translated by ER :

The National Geographic Institute (IGN) has confirmed to PEVOLCA, that the seismicity that began on June 24 continues, although it has declined since yesterday. IGN also indicates that the activity has shifted mainly to an area comprising the western ridge and the El Julan slopes.

In this regard PEVOLCA confirms that the current alert phases remain as they are. Translated by ER, it means that everybody can go and live where they want, even at El Julan or the western ridges as the state of the island in fully "normal" or green. No additional security measures are called.

Until noon today more than 300 earthquakes have been recorded, most of magnitude greater than 2, and with a maximum magnitude 3.8 and a maximum intensity of IV felt (EMS). The depth of the earthquakes is maintained at around 20 km (17 to 21 km). The earthquakes are not migrating to the surface.
ER comment : The real number of volcanic earthquakes is far greater than mentioned in this Pevolca press report. We estimate that is a factor 3 higher than officially admitted. Why ? IGN does not count the less than M1.3 earthquakes and they are mostly making the majority of the number. This number is almost always given by other agencies worldwide while mentioning the number of volcanic earthquakes.

IGN continues his surveillance and analysis on the basis of the real-time data obtained by the Volcanic Monitoring System operated by IGN El Hierro.

All information regarding the volcanic process will be reported by Pevolca.

ER general comment : nothing new at the Pevolca horizon.

Update 26/06 - 14:10 UTC
- Earthquakes keep coming on a regular basis, now with more than 127 since midnight. Energy liberated by these movements is on the rise as seen on the graph done by AVCAN which shows how it grows in almost a vertical line. This shows that contrary to what PEVOLCA say, the situation can't be just normal.

- By comparison to the previous months since the start of the year there is a huge difference! From IGN:
Update 26/06 - 11:32 UTC

- A few new pictures from Joke Volta. Unfortunately they do not reveal a lot due to the Calima

Images courtesy Joke Volta

Update 26/06 - 11:07 UTC
- 89 earthquakes so far today (IGN is still adding continuously).
- The location of the epicenter remains below the island and the hypocenter behave normal (18 - 20 km).
- The stronger earthquakes are in the M2.9 to M3.1 range. Most of the earthquakes are stronger than M2.0.

Important Update 26/06 - 10:30 UTC
- What looks in the seismogram as being a lot less activity than yesterday is not completely true as only the Harmonic Tremor (magma flow) has almost stopped completely. The accumulated pressure of the magma below the island is still very strong.
- Until 08:42 UTC, 77 earthquakes have been listed by IGN (M1.3 or stronger)

Joke Volta told us that she had felt the M2.9 which occurred this morning at 04:10 near El Pinar (05:10 local time). Joke lives in El Pinar. The IGN list, which is set up manually by IGN staff and is only published 2 hours after occurrence of the earthquakes, does not show a depth of this earthquake NOR does it show that this particular earthquake was felt by the people.
Remark from ER reader David which we endorse : Please note that event 1151344 has an unknown depth (the fixed depth flag is set in the IMS report), so by convention the depth is set at 0.0 and this is what is shown in the graph. No information hiding, at least in this case.

Update 26/06 - 07:56 UTC
- The strong Harmonic Tremor yesterday which was generated mainly by the gradually continuing flow in the lava tube system below the island from the El Golfo area to the Tanganasoga and El Julan has dispappeared completely today. The blocking effect seems to hold for the moment. New HT will most certainly lead to new epicenter locations and will give us a hint what to expect in the near future. Earthquakes are continuing however at a high rate (although less than yesterday).
- 43 earthquakes already today (until 05:08 UTC). IGN is till 2 hours behind in reporting (normally reports are arriving within 15 minutes from occurrence - we do not believe that IGN is hampering here, it must be a matter of personnel)
- 33 earthquakes have values of M2 or more
- 2 earthquakes had a value of resp. M3.0 and M3.1
- The depth of the hypocenter (focal depth or location where the action is triggered) still remains in the 18 to 21 km range
- The lave tubes are still blocked at the south-western edge of the island, preventing the lava to continue to the earlier opened crater / vent / cone 88 meters below the Las Calmas sea.
- the picture below (courtesy IGN) compares the activity from yesterday and today. The frequency of earthquakes remains high.

El Hierro volcano seismic activity - June 25 compared to June 26

Update 26/06 - 07:13 UTC - overview
- Another day in the El Hierro volcano saga. What looked as an almost terminated story was reactivated a couple of weeks ago by some weak earthquake swarms. The activity migrated towards the El Golfo bay where it also began in June / July 2011. What we witnessed yesterday was however an exceptional powerful volcanic earthquake swarm without any earlier comparison.
- While we are handicapped by IGN in comparing the early busy days with yesterday due to restructured ... public data (we have now much less data in the public domain than at the start of the activity in 2011), we witnessed yesterday 241 earthquakes with a magnitude higher than 1.3.
- Yesterday, El Hierro set a new record high both in numbers and in strength numbers since the beginning of the activity. The strongest day so far was on September 27, 2011 when 230 earthquakes from the same kind where counted. 10 days later activity started in the Las Calmas sea.
- The present situation is however totally different than in 2011. The depth of the earthquakes is currently 18 to 20 km, similar to the pre-eruptive period in 2011. When the Las Calmas sea activity started (poisoning the waters south of La Restinga) the depth of the epicenters shifted to 8 to 12 km.
- A lot of measuring equipment (with connected on line public data) has been dismantled in the meantime. Still enough though to make good decisions as the pattern of the volcano is better known today than in the early activity months of 2011.
- the biggest difference compared to the eruption months is however that the lava tube system beneath the Las Calmas sea seem to be blocked completely. Magma has traveled yesterday from the El Golfo Bay to the El Julan southern part of the island but cannot continue further on. The most logic scenario would be a reopening of the submarine crater / cone / vent who is currently 88 meter below the sea surface, but in order to reactivate the eruption that way, epicenters have to migrate to the Las Calmas Sea area and hypocenter should arrive in a depth of 8 to 12 km.
- The rest is looking into the future and will of course be explained in later updates.

Seismic activity at El Hierro since the beginning of the volcano awakening - Courtesy IGN - June numbers cannot be compared with earlier numbers (left side of the graph) as the June earthquakes less than M1.4 have NOT been counted, otherwise it should have been a record high (for sure)


Update 25/06 - 22:02 UTC
- A strong quake occurred at 21:37 UTC. We speculate the value to be around M3. As IGN is 2 hours behind we have no exact reading or location yet.

Update 25/06 - 18:55 UTC
- Seismicity is calming considerably the last couple of hours. It seems that the volcano has listened to the Pevolca board :).
- 121 M+2 earthquakes until 17:37 UTC today (149 total M+1.4) (This does not take into account the probably hundreds of earthquakes below M1.4 which were registered in 2011, but are only visible now for the IGN and INVOLCAN volcanologists).

HT and earthquakes at CHIE station on June 25 until the afternoon

Update 25/06 - 18:12 UTC - Pevolca press report (Gobierno de Canarias)
To most people, the decision of Pevolca will come as a surprise - no special precautions whatsoever, not even at El Julan where most of the earthquakes are centering now.
The Pevolca decision is however motivated by the lack of deformation of the island, by the depth of the earthquakes and by the lack of gas emissions. 20 km is ok for IGN and INVOLCAN (scientific partners in Pevolca).
The press report is also stating that IGN is following up the earthquakes in Realtime (not 2 hours behind schedule like they do with the public). Lets hope IGN and PEVOLCA have taken the right decision. We have to stress that they have been always right so far.
Lets make however an important remark : the route towards the traditional submarine cone seems still to be blocked and we still have earthquake close to M3 going on. If a major M+4 occurs, all scenarios are open.

Update 25/06 - 17:45 UTC
104 M+2 earthquakes so far and IGN lags at least 2 hours behind schedule

Update 25/06 - 15:45 UTC
-The number of earthquakes is picking up again
- Today will have the highest number of (M+2) earthquakes since September 30, 2011 (pre-eruption process at El Hierro). IGN has still a delay of several hours and we have counted already 88 M+2 earthquakes.
We have compared data from the full length of the eruption process. On November 3 (fierce action) 62 M+2 earthquakes were registered. On October 6, 2011, 88 M+2 were registered.

Update 25/06 - 15:28 UTC
- As stipulated in the 14:36 UTC update, we see a drastic decrease in number and strength of the earthquakes. It looks like the strongest swarm episode is over for now and we expect no further deterioration of the situation if the current activity continues.
- Earthquake Animation of Julio del Castillo Vivero in cooperation with Avcan - magma trail has been currently blocked at El Julan (last set of bullets)

Update 25/06 - 14:36 UTC
- We have the impression that, based on the HT hourly graphics, HT and the number of earthquakes has decreased considerably although we still notice strong ones. Probable explanation : Flow decreased due to blocked lava tubes, but pressurizes the paths even more which is related to a number of stronger quakes
- 82 earthquakes (the most important ones) listed by IGN until 12:12 UTC (we are now more than 2 hours later)
- The AVCAN map below shows the "road" the magma is following while pressurizing the below the island tunnels. The magma is gradually moving from the El Golfo island towards a cluster below the old volcano crater and finally towards El Julan (south coast). It still has to travel a little bit towards the submarine crater to restart the eruption process. The main question now is whether it will reach and reopen the cone or withdraw before that.

Map (without green line) courtesy AVCAN - quake locations based on official IGN list

The El Julan coast where the magma seems to have been blocked (last recorded group of listed earthquakes) - image Joke Volta

Update 25/06 - 13:40 UTC
- Spanish national tv news are starting to report on these earthquakes. There is no IGN/PEVOLCA explanation in the bulletin. Below, an image from La 1 of RTVE.

Update 25/06 - 13:00 UTC
- Local Canarias7 is reporting that PEVOLCA will meet urgently at 17:00 local time to discuss the current earthquake data. Urgently is a little exaggerated we think ...

Update 25/06 - 12:39 UTC
- Another strong earthquake occurred at 12:13 UTC. We do not know the location yet as it was not listed yet by IGN.
- The epicenters of the last sets of earthquakes (those listed by IGN) is gradually shifting towards the submarine Las Calmas vent.
- We consider this as the best possible scenario for a new eruption as the submarine vent is located at a safe distance out of the coast.
- So far 71 earthquakes have been listed, but there are much more earthquakes than those listed. Not only the most recent ones, but also those below M2.0 which have to be considered volcanic earthquakes too. In the initial reporting, these weaker earthquakes were also listed by IGN in a text format list, but IGN stopped publishing these (on political pressure ?)
- One particular listed earthquake attracted our attention and maybe a trace of what is coming :
The 10:25 M2.6 earthquake to the SW of El Pinar at a depth of 11 km. The shallower depth may indicate that the magma has arrived in the earlier open lava tube system below the shallow cone.

Update 25/06 - 12:01 UTC
- Another (not yet listed) strong earthquake occurred at 11:19 UTC. We expect it to be measuring in between M3.2 and M3.6

Update 25/06 - 11:42 UTC
- An M3.0 earthquake occurred out of the Tenerife coast but cannot be seen as directly related to the El Hierro activity.
- As ER is following earthquakes worldwide, we noticed some earthquake activity in the greater Azores area about 15 minutes prior to the activity of El Hierro. A direct relation is of course impossible to prove, but we simply noticed it.

Update 25/06 - 11:12 UTC
- For those readers thinking that the current HT is an eruption, we have to deny this. This is mainly magma movement. A real eruption, like in early November, will show an almost FULL HT graph.
Since a few weeks ER is publishing a daily Volcanic Activity (Volcanic Seismicity) post (daily posts since 2 days). These posts are showing clearly what you should see when a real eruption is taking place. Example 1 - Example 2 - Example 3

Update 25/06 - 10:56 UTC
- IGN has not listed new earthquakes since 2 hours now, but is still adding ones who occurred before 09:03 UTC. Their current number is 61
- Based on the CHIE HT graph, more earthquakes are occurring since the latest M3.8 earthquake.
- HT seems to be calmed a little, but this means only that the Magma transport is probably blocked by a plug in the lava tubes system. It may take another strong quake or some time to open this.

Update 25/06 - 10:27 UTC
- 55 earthquakes listed so far today by IGN (in reality these are only the strongest ones - bigger than 1.5). On a few exceptions all of the listed earthquakes are +M2.0. We would not be surprised that the real number of earthquakes (including the very weak ones which were included in the beginning of the eruption) would run into the hundreds (of course speculative).
- We are also convinced that if the eruption would be reactivated in the same cone at 88 meter of depth (like what happened in early November), a Surtseyan eruption will happen very rapidly. (Less than 100 meter is considered as a depth that Cypressoide action can start)
The location of the cone in the Las Calmas sea is far enough out of the coast to be considered as not dangerous for the population of the island. Only northern winds (which only happen now and then) can make a difference to that scenario.

At earthquake-report.com we think that the time has come to reinstall the WEBCAMS and to STOP PLAYING POLITICS (hiding information to the open public).

Update 25/06 - 10:12 UTC
- We are acquiring a Magnitude level that the main seismological agencies in the world will be picking up and reporting the El Hierro earthquakes. Mostly they start reporting from M4.0 onwards. Our own Daily complete list of earthquakes has been picking up the + M2.5 earthquakes.
- The last reported earthquake by IGN was at 09:03, but we see a number of new earthquakes since then on the HT graphs (bigger amplitude lines for some seconds).
- The current earthquake depth is not dangerous for the people on the island. BUT .... if the magma finds its way up and a few extremely shallow quakes occur (less than 3 km) an eruption can occur in a short time. In many cases a M 4+ earthquake triggers the eruption when magma channels are blocked.
- We trust on IGN to follow up the depth and the most recent set of the earthquakes with their SECRET data.

Update 25/06 - 09:45 UTC
- Events are getting stronger and stronger. The strongest quake so far is a M3.8 at a depth of 19 km at 09:03 UTC. The earthquake was felt as an MMI IV (light shaking) at some parts of the island.
- We expect a PEVOLCA report much sooner than their proposed afternoon meeting as the strength of the quakes is getting stronger and stronger. So far the depth remains at approx. 20 km, but
- There is a tendency that the epicenter of the quakes moves gradually to the earlier Las Calmas sea area (towards the earlier eruption cone).
- If the present set of earthquakes keeps getting stronger, all options are open, but surely a new eruption is imminent.
- Of course we have to be prudent to predict what would probably comes up, but the authorities have chosen NOT to share all available data with the public. We do not know at this time how the following parameters are changing : recent GPS inflation values (horizontal and vertical), micro-earthquakes, gas emission, etc.

Update 25/06 -09:05 UTC
- The comment section was automatically closed after 270 days (yes 270 days :) ). ER reader Colin attracted our attention to it and it has been reopened (thanks Colin).
- PEVOLCA (committee of scientists and Safety people) will be meeting this afternoon and will be discussing the report of the IGN specialists). Until then, we do not expect any official news.
- AVCAN has mapped the quakes reported by the IGN (see below). The violet bullet the M3.4 of today, the red bullets are today's earthquakes (38), the green bullets those of yesterday (16) and the yellow bullets the 120 quakes from June 1 to June 23.

Earthquakes map - courtesy AVCAN

Update 25/06 -08:16 UTC
- Joke reports that the visibility in the Las Calmas sea is very poor today due to the North African dust (Calima).
- She told us also that the people responsible for Safety at El Pinar (village level) have been following what is happening very closely since yesterdays strong earthquake.

Update 25/06 - 07:09 UTC
- Also today, the earthquakes are continuing and are even stronger than yesterday.
Especially to retain is a strong M3.3 quake, without a given depth below the island to the west of El Pinar.
- The real number of earthquakes maybe far more than listed at IGN as only the stronger ones are shown. The weak ones are seemingly not shown anymore.
The list so far today (keep in mind that IGN takes several hours to list the quakes - there maybe more up to now)

Update 25/06 - 06:57 UTC
- NO official comment as yet
- to show you a better picture of HT trend, we have compiled the hourly HT graphs since the strong earthquake yesterday evening
- 3 additional earthquakes have been listed by IGN yesterday evening, which brings the total to 16.
12 of these earthquakes were M2 or higher! This is definitely not a swarm like we have experienced them the last couple of weeks.
Details of the last 3 quakes :
23:46:16 Depth 18 km M 2.2 NW FRONTERA
23:48:30 Depth 18 km M 2.0 NW FRONTERA
23:54:09 Depth 19 km M 2.1 NW FRONTERA

Harmonic Tremor at El Hierro, Canary Islands, Spain from 24/06 late evening until 25/06 early morning.

Update 25/06 - 01:03 UTC
- our hispanic colleagues from AVCAN are requesting the authorities (IGN, Pevolca, ...) to confirm or deny officially that a new eruptive vent has been opened. The current tremor shows increasing magma movement and AVCAN says that the population of El Hierro has to right to know what is happening below their island.

Update 25/06 - 00:45 UTC
- 3 more earthquakes before midnight. All of these last earthquakes above M2
23:01:49 27.7828 -18.0264 Depth 19 km M 2.1 NW FRONTERA
23:08:00 27.7704 -18.0186 Depth 18 km M 2.0 NW FRONTERA
23:14:57 27.7667 -18.0259 Depth 19 km M 2.3 NW FRONTERA
- Harmonic Tremor grew even stronger than a couple of hours ago


Links to earlier parts of this extensive El Hierro eruption report :
(28/7 – early 09)(25/09 – 10/10) - (11/10 – 13/10) - (14/10 – 17-10) - (18/10 – 21/10) - (22/10 – 26/10 )(27/10 – 31/10 )(01/11 – 03/11 ) - (04/11 – 06/11 )(07/11 – 08/11)(09/11- 11/11)(12/11 – 15/11)(16/11 – 19/11)(20/11 – 23/11)(24/11 – 27/11)(28/11 – 02/12) - (03/12 – 07/12)(08/12 – 11/12)(12/12 – 15/12)(16/12 – 18/12)(19/12 – 25/12)(26/12 – 31/12)(01/01 – 03/01)(04/01 – 07/01)(08/01 – 13/01)(14/01 – 19/01) - (20/01 – 25/01) - (26/01 – 30/01) – (31/01 – 04/02) – (05/02 – 10/02) – (11/02 – 16/02) – (17/02 – 23/02) – (24/02 –29/02) – (1/03 – 10/03) – (11/03 – 18/03) - (19/03 - 23/03) - (24/03 - 28/03) - (29/03 - 03/04) - (04/04 - 10/04) - (11/04 – 21/04) - (22/04 – 30/04) - (01/05 – 10/05) - Part 43 (11/05 – 31/05) - Part 44 (01/06 – 14/06) - Part 45 (15/06 – 24/06)


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


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