El Hierro Volcano eruption (Canary Islands) : Part 47 – June 27 and June 28

This is Part 47 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 28/06 – 22:14 UTC
-The AVCAN image below shows the depth of the earthquakes since the swarm started on Sunday. The image shows a chaotic day depth-wise, Magma is currently active in many different layers below the island and the Las Calmas sea.

Map courtesy AVCAN

Update 28/06 – 21:50 UTC
- Everything looks rather normal today and people get used to the present conditions. Less strong earthquakes than yesterday bring a king of relief to the living conditions
- The process is however continuing just like the preceding days. IGN has listed 164 earthquakes so far, less than yesterday but still en enormous number.

Update 28/06 – 20:24 UTC
-Thanks to ER readers Sissel and Mafl who gave us both routing informations of the SAR aircraft and the Hesperides ship, we were able to see in the public domain the routing of both the aircraft and the ship.
Wat we earlier described as probably shipping related is not so sure anymore after gluing the 2 pictures together. It is of course normal that the authorities will not publish every move they are ordering in their research.
We also checked the NASA satellite image today, but it was to hazy to trace eventual discoloring . The common researched area is approx. 20 km to the south of La Restinga.
After some Ocean depth checking in Google earth, we found out that the submarine volcano cone were the plane and ship were circling is at a depth of 2000 meter (we know that that is not accurate, but it gives a clue of how deep we expect the volcano or seamount to be). Maybe todays flight and ship route were only meant to do some long planned research which has nothing to do with the current activity.
Update : As we were intrigued by this story, we remember an issue which occurred on October 10 2011, just before the sea at El Hierro started to color green. This is the text we wrote on October 10 (part 2 of the El Hierro story ) :
Following the Spanish Newspaper El Mundo, a small submarine eruption has taken place 7 km out of the coast. The eruption occurred at 1200 meter below sea level. The eruption took place in the Las Calmas sea to the south of the island at 10.43 local time (09:43 UTC). We expect an official statement soon.
The news comes from 4 boats presently navigating in the Las Calmas sea.
- The present conditions are however totally different than on October 10 (earthquake parameters). Another difference is that todays action took place at approx. 20 km out of the coast.

Click on the pictiure to see it in full format – image courtesy Marinetraffic.com

Same picture but combined with Google satellite view – - image courtesy Marinetraffic.com

Update 28/06 – 20:24 UTC
- The Volcano Watch CAP center in La Restinga, where Joke was a daily admirer and client, will be reactivated because of the continuing volcano crisis. CAP was the local IGN control room and IGN personnel was following all the locally installed instruments. After the closure, the CAP tasks were transmitted to the IGN headquarters in Madrid.

Update 28/06 – 19:31 UTC
- ER reader Mafl comments that a SAR Airplane has overflown the Las Calmas Sea to the South of La Restinga. These type of planes where earlier used to sample the air above the volcano vent, mostly at night. The plane is labeled normally as a Sea Rescue Plane. The routing which is shown on Marinetraffic.com looks not to be volcano related if we take into account the current earthquake epicenters and the area the plane has been criss-crossing (but the least we can say is that the criss-crossing is a strange way of overflying a sea). The flight may have been shipping related too.

Routing of the SAR Airplane – Image courtesy and copyright Marinetraffic.com

Update 28/06 – 18:36 UTC
- 138 earthquakes so far. 4 earthquakes measured M3 or higher. Strongest earthquake since midnight was M3.4.
- The hypocenters of the earthquakes are getting deeper again after a short period of shallower earthquakes. Harmonic tremor is still present and shows that there is still a lot of magma moving.

Update 28/06 – 16:25 UTC
- The strongly felt earthquake at El Pinar seems to be (only) a M3.4. It may have been felt stronger by the people because of the location of the epicenter which was this time below the coast at El Julan.
- In our morning overview we did indicate a few points to follow up carefully during the day. One of these possible triggers was a shallower depth. It looks like the magma is infiltrating gradually in higher rock segments.
We have noticed a M2 @ 15.9, M3 @16.2, M2.5 @ 16.2, M3.1 @ 17.1 km. Referring back to what we said earlier, these depths and epicenters were also activated on September 27, 2011 when the 2011 eruption increased in strength. ER readers who want to make the same comparison have to filter the September 27, 2011 values in this screen. To avoid an avalanche of data rows, set your minimal Magnitude to 2.3 and the end date of the filter to October 7.
Of course, all this does not prove anything, only that the area the magma seems to have found now is the same area and depth than during the latest eruption. This is the first time that this is happening since the earthquake swarm that started on June 24.
Update 18:34 – What looked like a set of shallower earthquakes has been reversed into deeper earthquakes in the 19 to 26 km range. This reverse happened at approx. 14:15 (M3.2 earthquake).

Update 28/06 – 16:22 UTC
Joke just wrote us a message that the shaking was very strong and that the people in El Pinar are guessing a 4 Magnitude, which is indeed very strong for a volcanic earthquake.

Update 28/06 – 16:13 UTC
- Still NO IGN listing of this powerful 15:32 earthquake. The CHIE graph was completely saturated and does not show the usual colors. We will have too wait until IGN updates the graph manually.
- X and Y axes and other information is currently empty on the IGN tremor graphs.

Update 28/06 – 15:59 UTC
- People on El Hierro are talking right now about a couple of strong to very strong shakings. As they are more and more specialized these days, they are guessing themselves how much IGN wil list later. Their current guess in El Pinar is M4 – at Frontera they guess a M3.
Sandra Izquierdo just wrote in Favebook : movimiento fuerte de nuevo en frontera – a new strong shaking in Frontera

Update 28/06 – 13:49 UTC
- 2 strong earthquakes occurred a short-while ago at depths of 17.2 and 17.1 km (M3 and M3.1). Check our own list for a map of the epicenters (use the zoom factor to see the details). The latter was felt by the people.
- IGN has changed policy in publishing from now on the deformation data again. thanks to the IGN for doing so. Check them out here.

Update 28/06 – 13:25 – New PEVOLCA press report (translated by ER)

We have observed a deformation of the entire island. The center of the deformation originates in the present earthquakes area (see below)
The energy release and ground deformation show an acceleration of the active magmatic process on the island of El Hierro, according to information forwarded by the National Geographic Institute at the direction of the Civil Protection Plan for Volcanic risk (PEVOLCA)
The GPS network solution, measuring the surface strain on the island shows that there is a clear process of inflation, marking an apparent center of pressure in the area where the seismicity is located. The total cumulative displacement from 24 June to 24 hours yesterday, is about 3-4 cm in the horizontal components and 4-5 cm in the vertical component.
Since the beginning of the new magmatic process on June 24, there have been over 750 earthquakes. An earthquake with a Magnitude 4.0, occurred yesterday at 18:55 pm in the Las Calmas Sea, 2 km from the coast and 20 km deep.
Be remembered as the seismicity started in the El Golfo bay, then moved to the center of the island, coinciding with the point of intersection of the ridges, and later migrated to the west. Since the 25th of June the seismicity is concentrated in the west and El Julan. From 12:00 hours. On 27th of June, seismicity began to migrate towards the Las Calmas sea.
Comment ER : Our regular readers will find 1 surprise in this press report (the rest has been treated in many updates) – the even stronger than expected vertical deformation of the island emphasizing the very strong energy below the island (4 to 5 cm).

Update 28/06 – 12:26 UTC
- The Oceanographic vessel Hesperides has been announced to arrive soon at the El Hierro waters. What the ship exactly will do is unknown (analyzing sea water looks evident to us) as the bathymetry will not have changed since the first eruption stopped a few months ago.
- Yesterday we have cut a big chunk from our main article. These parts are now saved in part 44 and 45 of the El Hierro volcano eruption history. The links to all the preceding parts can be found at the bottom of this page. We will soon cut another part of this page as it is reaching a critical size to be easily consulted by people with limited bandwidth like Colin.

Update 28/06 – 11:52 UTC
Since we announced the possibility to subscribe to our Spain-Only email earthquake notifications list, we have received a few hundred of subscriptions. We hope that these people will like our service. We want to stress however that, if you receive to many emails because you have set the earthquake level to M2.5, you can easily unsubscribe and subscribe again to a higher level. It is done in seconds. No passwords are needed. We also have seen that some people have not confirmed their Email address and haven’t received anything so far.
Our email containing the confirmation link may have arrived in your spam folder (although we are not spammers), so please check your spam folder in that case.

Map of current Yellow Alert area on the Island

June 27 Yellow Alert area at El Hierro, Canary Islands, Spain – Map courtesy Grafcan – Click on the map to view it in a bigger size

Update 28/06 – 11:10 UTC
New images from Joke Volta. She took some photographs this morning at the Tacoron crossroads. The visibility is better than the preceding days but the Calima has not completely disappeared yet as can be seen on the pictures. Click on them to watch them in our Picasa web-album. Joke also carefully examined the water surface and saw NO signs of any activity whatsoever (although it is not conclusive with this kind of visibility).

Update 28/06 – 08:45 UTC
New Rapid and Ultra-Rapid GPS deformation data from Prof. Sagiya from the University of Nagoya, Japan are showing a further increase in deformations at the FRON and PINA stations. Other stations like JULA, REST and SABI have not been updated since the swarm started.
IGN does also follow these deformations but has decided to stop publishing them (in 2011, these data were part of the El Hierro public site and refreshed with a delay of 1 to 2 days). Deformations are one of the many parameters volcanologists are following to predict eruptions and possible changes in the volcanic process.
Remark : this update has been rewritten after a comment of reader David that some stations did not showed the deformations of the last couple of days.

Update 28/06 – 07:55 UTC
- At least the people of El Hierro must have had a good night sleep as the strength of the earthquakes decreased seriously the last 7 hours. But … only the strong earthquakes were more or less silent at night.
- So far today IGN has listed 39 earthquakes since midnight, a little less than the preceding days, but still a high number.
- Harmonic Tremor has restarted strongly since 05:35 this morning, showing us that the volcanic process is still continuing strongly. As we have experienced the last couple of days, the current HT may refer to a new migration of the epicenters
- The strongest earthquake since midnight was a M2.8 earthquake. NO earthquakes since midnight have been marked as felt by the people. At ER we think that Felt or no felt indications are far from reality as most people do not indicate slight tremors anymore after having experienced stronger ones. Aftershocks in general are less documented. Only nations like Japan, USA and New Zealand are drilled to report whatever they have felt.
- The depth did not show a lot of difference since midnight with values in between 17.6 and 22.9 km
- The epicenter of the earthquakes since midnight remains the El Julan – La Dehesa area of the island
- We certainly expect more earthquakes to come today as the process continues in full strength.
- What can change the process fundamentally ? Our readers should watch the following elements in the current process with more focus than the rest : Depth of the earthquakes (changes towards a depth of 15 km or less can be triggers of new events, sudden change in the strength of the earthquakes, the locations of the epicenters (these locations are important in relation to the conduits of the recent eruption)

Locations of the epicenters of the last 10 earthquakes – map courtesy Avcan

Earthquakes and HT so far today

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Update 27/06 – 23:55 UTC
- Another very active day with a lot of earthquakes which have been felt by the people. The strongest so far this year was a M4 at 18:55 UTC.
- Earthquake epicenters have also gradually moved today from below the island towards the shallow waters of the Las Calmas sea. The movement has stopped in the late afternoon and continued at midnight in the same area (see picture below).
- At midnight IGN had listed 191 earthquakes. 10 earthquakes had a Magnitude of 3 or more
- The depth of the earthquake remains at 18 to 21 km (no change compared to yesterday)

This image shows the location of the epicenter of the 10 latest earthquakes before 17:05 (left) and 23:05 (right) – Location is almost similar – image courtesy Avcan

CHIE seismogram showing a lot of activity today

Update 27/06 – 19:45 UTC
The earthquakes epicenters are currently located at the same area where it all started on September 27, 2011. The depth at that time was approx. 15 to 17 km. The current depth is more in the 19 to 21 km range . The difference in between the 2 layers is a couple of kms. (All our readers can come to the same conclusion in comparing the location and the depth of the 10 days of earthquakes who started on September 27 and todays location of the quakes). All this is not conclusive in what will happen next.

Update 27/06 – 19:01 UTC
Joke has just SMS’t (texted) that she has felt a strong shock in El Pinar.
The earthquake Joke has just reported was a M4.0, the strongest earthquake since last year.
As you will be seeing on the map, the epicenter is located below the Las Calmas sea floor.
18:55:08 27.6883 -18.1006 Depth 20 km Sentido M 4.0 mbLg W EL PINAR

M4.0 earthquake in the Las Calmas sea close to the El Julan shore

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Update 27/06 – 18:47 UTC
Almost all the Spanish and Portuguese readers from Earthquake-report.com are gone! We think that they are watching the game Spain – Portugal for the European cup. Even at El Hierro, football will be dominant tonight

Update 27/06 – 16:36 UTC
Almost all the recent earthquake’s epicenters are gradually migrating south into the Las Calmas sea. The denomination ” SW FRONTERA” are gradually replaced by “W EL PINAR” when the epicenter is located in the Las Calmas sea.
The migration to the new area can also be observed in the existence of harmonic tremor which started also around 14:00 UTC.
It looks now that HT is diminishing again and that the earthquakes will remain in the same area until new HT appears (possibly started by some strong earthquakes).

Locotions of the epicenters during the mast set of earthquakes – map courtesy Avcan

Update 27/06 – 15:06 UTC
- 2 new strong earthquakes in 1 hour time + the reactivation of HT. Still the same (harmless) hypocenter depth
- Since midnight we have counted 6 earthquakes with Magnitude 3 or higher, the strongest ones being 2 M3.4′s the first 2 hours of June 27.

Update 27/06 – 14:23 UTC
A M3.3 earthquake which was felt by the population occurred at a depth of 19 km at 13:12 UTC on this epicenter location

Update 27/06 – 13:58 UTC
The official document stating the new Yellow Alert as described earlier. The Yellow alert area includes El Verodal or the western tip of the island, a steep dangerous coast with high bristle volcanic rocks. Landslides triggered by the earthquakes cannot be excluded here.

El Verodal western part of El Hierro – Images courtesy Julio del Castillo Vivero – click on this image to see them in full format

Update 27/06 – 13:23 UTC
INVOLCAN has also reported the CO2 values which they obtained via their partner ITER. The values have been recorded until today and are very normal taking into account the present conditions. The HIE01 ITER station is a mobile unit located in the El Pinar area.

Image courtesy and copyright Involcan

Update 27/06 – 13:03 UTC
- 104 earthquakes so far today
- the last several hours HT has nearly stopped and the frequency of earthquakes is also slightly downward

Important Update 27/06 – 12:32 UTC
Pevolca calls a Yellow alert in the unpopulated earthquake zone. In a live interview on RTVC, the local Canary Island TV and Radio station, María josé jurado has declared that the El Julan and La Dehesa area will be labeled as “Yellow Alert” area. Besides a church and a lighthouse, this area is unpopulated.
The move sounds logic to ER as the direct treat to other areas for eventual earthquake damage is very limited. Earthquakes are the main risk at this moment.

Map created by Julio del Castillo Vivero – Yellow area : approx. yellow alert area

Update 27/06 – 11:29 UTC
- a new strong M3.2 earthquake just happened at 10:55 UTC. Epicenter here.

Update 27/06 – 09:58 UTC
- Deformations, as described in the Involcan maps and report below, are generated by the Magma pressure and are one of the major indications to predict eruptions. Together with the strength of the earthquakes, the depth of the hypocenters and the emitted gases, they are used by volcanologists to send alerts and warnings to the public. The mitted gases are the uncertain factor in this case but didn’t we hear a couple of months ago that some sampling points were dismantled ?
- The Involcan informative note comes as a real blame to the IGN and PEVOLCA communications policy. These organizations should review their communication policy urgently. We live in 2012 and when people feel the earth shaking almost constantly like in Sabinosa, you cannot get away with a message that the state of the island is “normal”, even if this is scientifically true. We know that we are repeating ourselves over and over again but the present situation becomes hallucinate.

IMPORTANT UPDATE 27/06 – 09:39 UTC
INVOLCAN, partner in the PEVOLCA steering group has taken the initiative to send an informative note to a lot of people (this message arrived to us via Joke Volta). Involcan is not longer tied to the poor communication of Pevolca and is alerting the island about much more stronger deformation than seen in 2011. EW (deformation to the East), NS (deformation to the North) and UD (vertical deformation)
(translated by ER)

We inform you about the observed shift of the GPS network Canaria (ITER + University of Nagoya + GRAFCAN) who is operating the Instituto Volcanológico de Canarias under the direction of Dr. Takeshi Sagiya (Professor of Nagoya University and Scientific Collaborator INVOLCAN .)

GPS STATION PINA (EL PINAR) :
During the last 2 days there has been horizontal eastward displacement of 2 cm and northward of 3 cm. The vertical displacement was 2 cm.
These data clearly reflect deformation ( a process of movement of magma underground and the source responsible for this deformation is in the central-western part of the island of El Hierro) in conjunction with data from recent seismic activity.
The movements recorded during the last 2 days are real and much faster than those observed last year 2011.

Involcan deformation graphs

Update 27/06 – 09:26 UTC
Joke Volta reports from El Pinar : People in Sabinosa (El Golfo area and rather close to the earthquake epicenters) almost did not sleep at night. They went sleeping downstairs, too afraid to be on the first stock… Further on, I did felt a few strong quakes, and called at the emergency center a few times in the middle of the night, for being able to list the quakes felt by the population. (which the government will close, but that’s another story …) . We will see what the rest of the day will offer us.

Update 27/06 – 09:11 UTC
- The plotted Avcan maps have given us the opportunity to show how the magma is eating his path below the island. Minute after minute Magma tries to find the weakest spots below the island. Old historic lava tubes and magma chambers are used to find his path to the surface. Unsuccessful so far !

Click on the image to watch it in full size – plotted maps courtesy Avcan

Update 27/06 – 08:40 UTC
- Another strong M3.3 earthquake occurred to the east of the lighthouse area. The earthquakes are too deep and not strong enough to generate any damage but of course are frightening the people a lot.
- The image below is courtesy and copyright ER reader Ian Carson. Ian was at El Hierro earlier this year when the volcano was still coloring the sea surface (the coloring of the sea surface on his photo are however normal sea currents as the picture dates from May 2012). The green dot is the location of the picture. One the picture historic cinder cone eruption crater can be observed. The exact time of this eruption was not documented.
- The number of earthquakes has increased in the meantime to 64.

Image of the El Hierro lighthouse area – courtesy and copyright Ian Carson

Update 27/06 – 07:44 UTC – overview of the last several hours
- Seismic activity remained strong all night with regular strong volcanic earthquakes (in this case we speak of strong earthquakes in between M3.0 and M3.5).
- So far today IGN has listed 50 earthquakes, which is about the same than yesterday (little less)
- 3 earthquakes were recorded as M3 or greater
- The magma is still imprisoned below the South-Western ridge of the island and the coastal El Julan area.
- HT shows minor magma movement at this time.
- More strong earthquakes can be expected today or as always with volcanoes, everything can stop suddenly – all options are open
- We expect a little more information from Pevolca today regarding deformation and gas emission levels (IGN or INVOLCAN are not allowed to discuss the matter directly with the press)
- People who subscribed to our earthquake notification system (see below) may have remarked that some quake notifications are arriving late, especially the <M3.0 ones. This is not caused by our system which immediately takes care of what arrives from the agencies, but is due to the late filling up of the IGN list (IGN treats the higher Magnitudes with a higher priority)

Harmonic tremor in between 05 and 06 UTC (06 to 07 local time)

Update 27/06 – 00:40 UTC
- Another strong M3.4 earthquake had an epicenter close to the El Julan coastal waters. Depth remains at 19 km.
- Slightly sleeping people at El Pinar (Frontera seems to have been shaken less) will spend a bad night with these M3+ tremors!
- We will definitely cut this article into 3 tomorrow morning.
- 4 earthquakes have been felt by the people since late June 26.

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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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