El Hierro Volcano eruption (Canary Islands) : Part 48 – June 29 until July 1

This is Part 48 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 01/07 - 22:36 UTC
- 107 earthquakes until 21:02 UTC
- The number and strength of the earthquakes decreased further today
- We are noticing a gradually increasing number of shallower quakes in the 15 to 18 km depth range. 15% today. The epicenters of these quakes are mainly located in the Las Calmas sea to the South of the lighthouse and are gradually moving to the East.

Strong earthquake at Nabro Volcano, Eritrea
Those among you who know this site already since the beginning, do know that Earthquake-Report.com was the first in the world (75% with the help of his readers) to detect the eruption of a historically silent Nabro volcano. This volcano , which was silent again since many months, now showed his adrenaline with a powerful M4.8 earthquake. We have written a small update in our original article. Click here to read it.

Update 01/07 - 16:42 UTC
New PEVOLCA report confirms strong vertical and horizontal deformation. We spare you all details of the report but we have linked the Logo from the government and the title from the report to the official press statement for those people understanding Spanish.
- Volcanic process continues in the same way as the last couple of days
- Seismicity is the latest 24 hours (they mean yesterday) repartitioned over a wider area and the hypocenter depths are also more variable than before
- Pevolca gives then the total number of earthquakes, data which already old right now. Additionally we at ER are convinced that the real number is far higher than officially reported. 165 earthquakes had a Magnitude of 2.7 or more (thats of course a correct number).
- Horizontal deformation has increased to 6 cm (total deformation from the the start of the new swarm) and 7.5 cm! vertically.
- Water and air are sampled on a regular basis and only the CO2 water component showed a slight change (has to be confirmed by laboratory analysis). The analysis stations working in real-time have however not reported abnormal values.
- SO2 values showed normal values

Update 01/07 - 12:44 UTC
-IGN has decreased the preliminary Magnitude from 4.2 to 4.0

Update 01/07 - 12:20 UTC
- ER reader Daniel commented with a question : which was the biggest Magnitude during 2011 ? It was a 4.6 on November 11. You can find our reporting here.
This is the table with Magnitudes 4 or higher :

Update 01/07 - 11:58 UTC
- We have just cut 2 parts of this always longer El Hierro story. All updates from June 25 to June 28 have been archived in 2 parts (Parts 46 and part 47). The links to these parts can be found at the bottom of this page.
- Mostly the bigger size earthquakes are triggering a series of strong quakes and some harmonic tremor. The latest M4.2 hasn't done that at all!
- 55 earthquakes have been listed by IGN so far (it should be more, but we guess they have less personal on a Sunday and can't cope with whats happening.

Update 01/07 - 10:42 UTC
- A new strong earthquake was felt by the population at 10:13 UTC. Based on the graph it must be certainly a M+3. IGN just reported a Magnitude of 4.2 at a depth of 22 km. Epicenter in the Las Calmas Sea.

Update 01/07 - 09:52 UTC
- Yesterday evening we still wrote that the earthquakes were concentrating below land and at the western tip of the island. During the night and certainly the last several hours, the AVCAN map below shows clearly that seismicity has moved again into the Las Calmas sea
- IGN has listed 50 earthquakes so far today (a little less than yesterday at the same time)

Epicenter map during the last several hours - map courtesy Avcan

Update 01/07 - 08:45 UTC
This is the overview of the last several hours
- The night started with very strong action. One of the more powerful M3.6 earthquakes was the beginning of 45 minutes of many earthquakes combined with harmonic tremor.
- Since 08:28 UTC this morning and after another stronger earthquake some more activity is happening again. Curious at which depths this is happening.
- In general nothing has changed as the initially reached shallower layers could resist well. Since then the depths are again at the normal 19 to 21 km, with the exception of a couple of specific quakes which should be followed with more than normal attention. At 00:10 an M2.9 earthquake occurred in the Las Calmas sea at a depth of 11.9 km (the average depth of the earthquakes during the last eruption). Epicenter was located to the south of the Lighthouse and at the latitude of La Restinga. Another (M2.2) earthquake which attracted our attention happened at 06:08 at a depth of 16.2 km. The epicenter plotted on a satellite map reveals that this epicenter is relatively close to the buildup of the 2011 formed new crater / vent. More of similar earthquakes may make the difference for the next several days if the pressure from below continues.
- We do not believe that the El Golfo earthquake who is listed at a depth of 1 km is correct. The depth in the epicenter part of the El Golfo bay is 1,206 meter. Additionally, there were no other signs of action in the direct vicinity of this epicenter.
- Based on the deformation graphs of de University of Nagoya, the (Ultra Rapid) deformation values showed a further increase in all directions (horizontally to the North-East and up vertically), although it has to be said that the increase is less than the day before.
- We have added the Italian and Greek volcanoes to our Volcano seismicity list (explanation below). Click here to see what we are talking about.

El Hierro seismogram since midnight July 1 2012 - image courtesy IGN


GPS station - image courtesy Julio del Castillo Vivero - Click on the picture to watch it in a bigger size

Update 30/06 - 22:13 UTC
- Difficult times for Joke Volta. An almost impossible task to get close to the current infiltration area (concentrated area of earthquakes west of the lighthouse or Orchilla), this because Joke has no car and has to use public transport to get to other places. Of course no buses are driving to an unpopulated area like the lighthouse area. Joke has taken some pictures from Tembargena, the most remote place she can reach after some serious walk and offering a distant view of this area. She is aware that she has to look on the water color of the Las Calmas sea to spot anomalies. Whenever some activity would occur in this part of the Las Calmas sea, it will be again the same story than before (very poisonous water and strong coloring), mainly because the vegetation on that point of the Sea has not been affected by an eruption yet.
The different colors which can be seen on the images describes Joke as currents.

Update 30/06 - 22:13 UTC
- A new strong M3.6 earthquake was felt all over El Hierro. Epicenter of this earthquake was south of most earthquakes today in the Las Calmas sea. Depth : 20 km.
- Pevolca confirmed the nearly 6 cm vertical deformation as reported this morning. They also confirmed the horizontal information of 5 cm since the beginning of the earthquakes swarm.

Update 30/06 - 20:02 UTC
- Since 07:20 UTC HT has stopped and only earthquakes are still happening. Strong enough to talk about a continuing process.
- 116 earthquakes since midnight today
- ER is always looking to improve his website and to inform his readers the best possible way. Since we have programmed our earthquake database and linked "I Have Felt It" forms, we are trying to optimize the output. Until today we are using our realtime earthquakes database for our daily major and complete earthquake lists, our Worldwide Earthquake lists and for our Email notification service. While following the El Hierro eruption, we also would liked to be informed about the earthquakes on El Hierro. As we had programmed a Spain-Only earthquake list and not too much earthquakes are happening in Spain, we had not too many other earthquakes to deal with. Other areas in the world make a different story. To avoid such overlapping, we have now created an example of what should become a "Worldwide Volcano earthquakes" page. As an example, we have created a list for El Hierro, La Palma and Tenerife. We have limited the scope of the location to the surroundings of the volcano. An Email Earthquake Notification subscription is possible for every list. Same principle as discussed below. You can subscribe to as many lists as you would like. Try to avoid overlapping lists.

Update 30/06 - 12:30 UTC
- Involcan reported that the Mobile analysis unit HI01 hasn't noticed changes in CO2 values
- ER reader Ecco commented below that our deformation graph was outdated (published by Involcan a couple hours ago). We checked it and found that Ecco is right. The Ultra Rapid upward deformation is nearly 6 cm at Prof. Sagiya Frontera station, a serious increase vs the last couple of days (see picture below). If you click on the image, you will be linked with the latest deformation graph which includes also the horizontal deformation. (Thank you Ecco)

Latest deformation change - image courtesy University of Nagoya, Japan

This is a very interesting video explaining how GPS data has to be read - good idea from Involcan to post it on their website

Update 30/06 - 10:43 UTC
- Joke has taken an number of pictures from the distant lighthouse area, but no anomalies have been seen
- A reader tells us that the INVOLCAN is ready to stay at El Hierro for another 30 days. They will pay the expenses out of their own pockets. An El Hierro resident has offered to house the Involcan people.
- 59 earthquakes so far today
- The epicenters of the latest 12 earthquakes seem to concentrate around the lighthouse area (on or off the coast). Depths are gradually shallower in a concentrated area, which means that magma is gradually infiltrating in upper layers.
- Deformation continues to increase, although at a lesser rate (see Involcan-University Nagoya graphs below). We have noticed the same increase in the IGN deformation data.

Screenshot AVCAN earthquake epicenter map - courtesy Avcan

Deformation map courtesy Involcan and University of Nagoya

Update 30/06 - 07:21 UTC
- Earthquakes continued all night long
- The earthquakes list yesterday was finalized on 195 earthquakes!, earlier described as weaker
- IGN has listed 41 earthquakes so far today, almost equal than the preceding days
- 1 of these earthquakes had a Magnitude of 3.0
- The depth is unchanged at 18 to 21 km with only a few exceptions
- The location of the epicenter is still west of the Lighthouse, partly below the island and partly in the close to the coast Las Calmas sea

Earthquakes and HT so far today

Update 29/06 - 23:55 UTC
- 40 minutes of strong activity started at 20:45 UTC
- Epicenters of the last batch of listed earthquakes are almost all located to the west of the lighthouse. The hypocenters or getting bit by bit shallower
- A number of quakes tonight have been felt by the El Hierro people
- 168 earthquakes have been listed on June 29
- The last 17 earthquakes were all more than M2!

Update 29/06 - 22:19 UTC
- A couple of strong M3 earthquakes have rattled the island recently.
- We are currently working at a very strong earthquake in China. Very shallow and M6.6, in other words EXTREMELY dangerous. Luckily in a sparsely populated area. If you are interested in following the events of this earthquake, click on this link to read our in depth article. The current article will remain open.

Update 29/06 - 18:46 UTC
- 136 earthquakes have been listed so far at IGN
- Still a lot of earthquakes. The depth still at 18 to 21 km
- The latest 20 earthquake's epicenters are in average migrated to the north-west below the western tip of the island as can be seen on the Avcan image below (earlier today merely in the Las Calmas sea)

Image courtesy Avcan

Update 29/06 - 19:21 UTC
- The images below have been taken by Joke Volta on May 5 near the lighthouse (part of the yellow alert area now)

Earthquake numbers and Earthquake numbers
Those among you following this El Hierro eruption event from the beginning may remind that IGN used up to a few months ago, 2 different earthquake lists. 1 list like we still have now with all scientific data for each listed earthquake and another text only list only mentioning Magnitude, location parameters and a few other data. This old list contained much more earthquakes than the clean html list.
The smaller earthquakes are still very well visible on the detailed hourly HT graphs and we have counted them during the first 5 hours after midnight. During that period IGN has listed 30 earthquakes. We have counted 226 earthquakes (some of them very weak of course). Remember from the first months of the eruptions mentions of over 10,000 earthquakes (even IGN used these numbers) - these numbers were obtained in adding also the weak and very weak earthquakes in the final count. IGN will certainly continue using the same data format to describe the current events in scientific circles.
Why do we tell you this ? Because any comparison about the total number of earthquakes is now impossible in between the 2 events ! We still hope that IGN will republish the old TEXT list.
On the positive side, we have noticed that IGN is gradually posting also weaker earthquakes in the list, today even 2 M0.9's.
Answer reader Max via our comments : The old txt EQ list hasn’t gone anywhere and is updated regularly. It’s rather big nowadays. So there’s no link anymore on IGN to boletin_HIERRO.txt? ER: Thanks Max, the list is indeed still present on the old url, but IGN does unfortunately not show the lower magnitudes anymore.

Green dots are the only listed earthquakes - the others are clearly visible but have not been listed

Update 29/06 - 14:32 UTC - Pevolca press report
-I think official communication will never be efficient, but this time they are not to blame :). The moment Pevolca published a new press report stressing a weakening of the process, the volcano answered with increased seismicity and 5 stronger earthquakes in 40 minutes! (in the meantime HT has decreased to normal levels again)
- The full text in Spanish can be found by clicking on the Gobierno de Canarias logo and Spanish text
Most important elements freely translated by ER (most of it is already known by our readers) :
- decrease in seismic energy during the last 24 hours
- 933 earthquakes since June 24
- 123 earthquake of Magnitude 2.7 or higher!
- no hypocenter migration towards the surface
- deformation of the island is still increasing but with a lesser increase than the first 3 days (4 cm horizontal and 4 to 5 cm (5cm = 2 inches) vertically (these are IGN data)
- Pevolca specifies separately the INVOLCAN (in fact the University of Nagoya) deformation data, which are almost similar to the IGN data (ER : we think that this is part of the war of science in the background of this process)
- ITER-Involcan has NOT detected any abnormal CO2 or SO2 values in their sampling stations so far
- Although the current seismicity is located mainly in a unpopulated area of the island (thank the many God's for that), Pevolca has decided to reinforce the RESCAN communications equipment (PMA). This is only a precautionary measure.
- ER : Of course NO word of the SAR airplane and Hesperides ship scan in the Las Calmas sea yesterday (see story below).

PEVOLCA press report of the Gobierno de Canarias

Advanced communications equipment as photographed by Ian Carson during his visit at El Hierro during the island alert phase - image courtesy and copyright Ian Carson

Update 29/06 - 13:43 UTC
- 105 earthquakes so far today ! The weakening of the process has been reversed the last couple of hours (stronger).
- The depth of the earthquakes is again upwards, this after a chaotic period yesterday and earlier today.
- Since 12:41 UTC, harmonic tremor and earthquakes started to pick-up again. Our readers checking our pages a number of times a day should check the depth and the location of the earthquakes after 12:41 UTC. The increased HT is a new magma flow who fills up new lava tubes, cracks etc. Once it is filled up it HT will decrease again. The vertical lines on the graphs are earthquakes (minor (not reported by IGN these days) and major alike).
- Image by Joke Volta from this morning. A zoomed picture of the La Restinga reef area : nothing special on the sea surface

Other volcano news
For ER readers interested in volcano activity in the rest of the world, we let you know the existence of our Daily Activity page. The page is a daily roundup of major activity. Click here to see the example from June 28. The links to these daily updates can be found on the frontpage.

Update 29/06 - 07:53 UTC
Our Canary Islands colleagues of AVCAN (Spanish) have invested a lot of energy in an attempt to visualize the hypocenters of the recent earthquake swarms who have started early June, this in relation with the deeper island layers. The orange lines in the video are the contours of the submersed rock island layers (island buildup).
For some of you it may come as a surprise that there are even earthquakes below the deepest layers of the island. The geology of an island is not rock and liquid magma below it as many may expect, but gradually hotter solid layers. These solid layers are also generating earthquakes if too much energy is added.

Update 29/06 - 07:21 UTC
- The magma pressure seems to be calming down. This based on the number and the strength of the earthquakes since midnight. The same decrease occurred in data terms in 2011. We will show this comparison chart later in the day.
- Thursday June 28 recorded finally 180 earthquakes
- Since midnight today IGN has listed 30 earthquakes, which means a decrease of approx. 30% compared to the same period yesterday
- The strongest earthquake since midnight was a M3.1 quake at a depth of 21 km at 00:25 UTC. 2 earthquakes reached M3.0 or more.
- Even when the process slowed down a little based on the earthquakes, readers should continue looking at any fundamental change in earthquake depth and migration of earthquake epicenters.
- We are looking out at a possible official explanation for the activity of the SAR (Search and Rescue) plane and the Hesperides Oceanographic ship. Ship and airplane were especially looking at a narrow area 20 km to the South-East of La Restinga on top of a volcanic seamount.

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