Damaging earthquake near Albacete, Spain (felt in Sevilla, Segovia, Murcia and Madrid)
Last update: February 23, 2015 at 10:47 pm by By Armand Vervaeck
Update : 3 fracking concessions have been granted in the greater Albaceite area, one in . Fracking in seismically active areas can increase or lubricate faults like in Oklahoma USA when waste water is re-injected in the underground. Fracking is a very contested practice in seismic areas. The depth of the hypocenter (breaking point) refers however to a non-fracking earthquake.
Update : We have reports of slights damage in many houses in a wide area, mostly cracks in walls
Update 17:40 UTC : The Spanish newspaper El Mundo reports that today’s earthquake happened along the same fault that triggered the deadly Lorca earthquake, which does not prove to be true based on the faulting map below. There are however a number of known faults as can be seen.
Update 17:31 UTC : En Ossa de Montiel algunas tejas de casas se han caído, con peligro para los habitantes de esas casas y para las personas que pasaban por la calle en esos momentos. (source : albeceteabierto.es) – Translation : falling tiles, people are now on the streets
Update 17:20 UTC : IGN (Spain) has now lowered the Magnitude from an initial M5.4 to M5.2
Update 17:13 UTC : shaking intensity map as generated by EMSC
Update 17:00 UTC : Map with epicenter as reported buy IGN Spain
Update 16:50 UTC : Especially the villages Ossa de Montiel and Ruidera are locations were damage may be possible. Brick houses are very vulnerable for cracks.
Update 16:49 UTC : Based on our Social Media searches, several people are currently reporting cracks in walls.
Update 16:47 UTC : Based on the satellite image below there might have been an interaction in between a fault and the lubrication of the nearby reservoir, something which happens regularly in other parts of the world. Scientific study will be needed to find out what triggered this earthquake.
Update 16:43 UTC : IGN Spain is now mentioning a M5.4 Magnitude
Update 16:40 UTC : Initial reports are reporting a depth varying from 10 to 23 km. The fact that this earthquake was femt in a relatively large area may explain that the 23 km is right.
163 km SE of Madrid, Spain / pop: 3,255,944 / local time: 17:16:30.6 2015-02-23
133 km SE of Toledo, Spain / pop: 82,291 / local time: 17:16:30.6 2015-02-23
83 km W of Albacete, Spain / pop: 169,716 / local time: 17:16:30.6 2015-02-23
20 km E of Tomelloso, Spain / pop: 38,095 / local time: 17:16:30.6 2015-02-23
Most important Earthquake Data:
Magnitude : 4.6
Local Time (conversion only below land) : 2015-02-23 17:16:30
El Hierro Volcano activity report – Continued (mixed) upward deformation – New deformation data (Dec. 26)
Last update: December 26, 2013 at 12:10 pm by By Armand Vervaeck
2013-12-26 12:07 UTC To make the deformation graphs a bit easier to read for our readers, we have created a map showing the axis where the most lifting has been noticed until the latest incoming data. Most earthquakes did occur and continue to occur to the East and South-East of the HI08 GPS station
2013-12-26 11:00 UTC IGN has just released new Ultra Rapid deformation data showing a continuous lifting in some parts and a stagnation in other parts.
The island inflates further with 1.5 cm in both HI08 (El Pinar) and HI09 (La Restinga) which brings the strongest inflation area 7 cm higher than prior to the crisis.
HI02 and HI03 (Sabinosa – El Golfo area) are stagnating or even deflating a little.
HI01 and FRON are lifting also another 1.5 cm.
Will be followed …
Click on this image to see the details in full size
Click on this image to see the details in full size
2013-12-26 09:16 UTC Still only a few earthquakes since midnight, but this may change based on the latest data not yet included in the list.
Volcanic tremor (indicating magma movement, still deep below the island) has been recorded by many instruments on the island.
The Upwards deformation was also confirmed by the latest Involcan/Uni of Nagoya PINA GPS station. In order to reference the current deformation vs the deformations from earlier crisis, we have included the PINA Involcan/Uni of Nagoya GPS data sheet (unfortunately the Pre-2012 data is not included). The increase we witness now can indeed be called “spectacular”.
2013-12-25 22:58 UTC – A very interesting new episode in the current crisis. A calm seismic period but a continued deformation, both vertical and horizontal. In earlier crisis, once the seismic unrest stopped, also the deformation leveled or stagnated. No the lifting continues in most points as the latest IGN GPS stations are showing. All this means that this crisis is not over yet and that new seismicity is evident when the island is pushed upwards. The Upwards deformation data are really spectacular (U side of the graphs) – In only 3 days HI09 (La Restinga) lifted 6 cm! and HI08 (El Pinar) 5 cm. But not only the South-Eastern side of the island was lifted, but also most of the El Golfo area with an average of 4 cm.
for more information, go to: http://earthquake-report.com/2011/09/25/el-hierro-canary-islands-spain-volcanic-risk-alert-increased-to-yellow/
El Hierro Volcano : Green pre-alert – A new earthquake swarm has started below El Hierro – 40 earthquakes until 13:47 UTC
Last update: August 16, 2012 at 4:32 pm by By Armand Vervaeck
Update 16/08 – 16:25 UTC
– 3 more earthquakes from M0.9 to M1.1 at a depth of 11 to 12 km (12:25 to 13:47 UTC)
– Maybe IGN could take a few courses in press reporting at GNS Science New Zealand. If an important new swarm starts, like the one today (even with weak earthquakes), an experienced volcanologist may write 5 sentences in explaining what the opinion of the organization is. Why does a body like Pevolca is to be used for volcanology ? If i would live in Sabinosa, i would love to hear a few words if continuous quakes are occurring below my house.
Update 16/08 – 13:37 UTC
– 5 more earthquakes in between M0.6 and M1.2 and at depths in between 10 and 11 km
Image courtesy Avcan
Update 16/08 – 11:53 UTC
– We have to continue bringing updates on the seismicity below the island. 4 more earthquakes bringing the total on 32 today. Magnitudes from M1.0 until M1.5. Depths 10-11 km. IGN has updated his list up to 08:30 UTC
– At right a small map with the epicenters of a number of the latest earthquakes.
Update 16/08 – 09:50 UTC
– 1 earthquake has to be added since our latest update (07:29 – 11 km depth – Magnitude M 1.5)
– For your comfort, we have cut 2/3ths of this article. Parts 49 and 50 (yes 50!) have been archived. Links to all those 50 parts can be found at the bottom of this page.
The latest 10 earthquake epicenters – image ourtesy Avcan
Very important Update 16/08 – 08:19 UTC – A new earthquake swarm has started below El Hierro
– For the 3th day in a row the number of earthquakes are fundamentally increasing below El Hierro. Although not official, we think that speaking of a new earthquake swarm is the only right way of describing the current set of earthquakes.
– No less than 26 earthquakes occurred this morning (from midnight UTC until 07:00 AM)
– The majority of the earthquakes are still weak, but the M2.2 from early this morning was the strongest in a while and the Magnitude pattern tends to become stronger every couple of hours.
– The CHIE seismogram is not showing a lot of action, but the M2.2 can well be seen. CHIE is not the best station at the moment to show the seismic events at his best.
– The depth is continuing around the 10 to 12 km which is a complete difference from the July swarm, but still far away from an eruption. More seismicity at lesser depths is needed to create a pre-eruptive condition. Newt to seismicity, we have also the gas analysis, the deformation, etc who will have to confirm if the present swarm will end in an eruption. The magma pressure should be powerful enough to find his way up.
– We do not know how many University of Nagoya GPS stations are still working, but we know for sure that FRON station still works and shows a vertical increase of many mm, which sounds normal after the present set of increasing earthquakes in the area.
– A reason for concern at this time should be the location of the seismicity (El Golfo Bay and Sabinosa area – including the cliffs south of Sabinosa). Landslides and rockfall may become dangerous at Magnitudes from M4 and up.
for more information, history, and updates, go to: http://earthquake-report.com/2011/09/25/el-hierro-canary-islands-spain-volcanic-risk-alert-increased-to-yellow/
Update 14/07 – 21:13 UTC
– At 19:52 UTC, El Hierro got another (but luckily isolated) strong M 3,4 earthquake. The epicenter was at the usual lighthouse area and the depth was reported at 20 km. People at El Hierro are reporting that they have felt this earthquake.
– This last earthquake brings the total number listed by IGN today on 9.
– Joke did her best to show our readers how El Hierro looked today. Click on the images to watch the photos in their real size.
Update 14/07 – 15:53 UTC
– 7 earthquakes so far. Depth 18 to 24 km.
Update 14/07 – 14:02 UTC
– 4 earthquakes since midnight. The strongest being a M2,5 earthquake at 13:13 UTC. Depth 18 km.
Update 14/07 – 10:26 UTC
– Only 1 very weak M0.6 earthquake at 01:52 UTC – depth : 20 km
– Vertical deformations as showed in Univ. of NagoyaGPS station graphs are generally down, another sign of the decreasing to halted activity
– Based on what we have seen the last couple of days, we can conclude that the current activity is over. We will (of course) continue to follow up what will happen in the coming days and weeks as a new swarm maybe possible.
Update 13/07 – 21:50 UTC
– 15 earthquakes so far today
– The latest earthquake listed by IGN occurred at 09:44 UTC!
– Joke Volta made 3 pictures today + a report that there was nothing to report. How events can change in such a short time!
Update 13/07 – 07:29 UTC
– Yesterday has ended with a total of 12 “deep” earthquakes (17 to 23 km).
– Today was “earthquake-free” until 05:05. This period was followed by a weak new swarm of 8 earthquakes varying from M1,9 until M2,2. The epicenters were all located in the Las Calmas sea to the south of the lighthouse.
– In our Daily volcano activity report from yesterday July 12, we gave more information about volcanoes in Colombia, Mexico, Ecuador, Indonesia, Papua New Guinea, Nicaragua and the USA. Click here to read it.
Update 12/07 – 23:08 UTC
– The day will probably end with 10 earthquakes, the smallest number since June 24. Unless something exceptional will happen, we can conclude that the swarm is over without creating a big risk for an eruption.
Update 12/07 – 15:00 UTC
– 9 earthquakes so far today. NO change in depths or epicenter areas.
– New images from Joke Volta from a couple of hours ago. No special news to report.
Update 12/07 – 08:34 UTC
– 3 earthquakes so far today. The swarm looks to have been ended completely
– A rather strong M3,0 earthquake occurred at 05:30 this morning
– Deformations are or stabilized or are decreasing in the vertical component
– yesterday, the day ended with 22 earthquakes
– the depth never changed fundamentally and may have been the main reason why the recent eruption lava tubes were not found by the new magma feeders
for more information and updates, go to: http://earthquake-report.com/2011/09/25/el-hierro-canary-islands-spain-volcanic-risk-alert-increased-to-yellow/
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
for more information and updates, go to: http://earthquake-report.com/2011/09/25/el-hierro-canary-islands-spain-volcanic-risk-alert-increased-to-yellow/
Update 14/06 – 13:00 UTC – An increasing number of earthquakes, what is called an earthquake swarm, took place in the early hours this morning. Up to 19 earthquakes in less than 3 hours. Magnitudes have been high, with one reaching M 2.8. All depths in between 19 and 26 km. According to IGN this is normal and part of the seismic process and not the eruption. -Map done by AVCAN website with full list of earthquakes here:
Event
Date
Time
Lat
Lon
Depth
(km)
Mag
Location
1148498
14/06/2012
04:00:02
27.7251
-17.9972
20
0.5
NW EL PINAR.IHI
1148500
14/06/2012
04:32:09
27.7622
-18.0380
22
1.5
W FRONTERA.IHI
1148507
14/06/2012
04:40:20
27.7481
-18.0339
20
2.3
W FRONTERA.IHI
1148514
14/06/2012
04:46:49
27.7432
-18.0379
23
1.4
SW FRONTERA.IHI
1148515
14/06/2012
04:52:39
27.7834
-18.0411
24
1.9
NW FRONTERA.IHI
1148530
14/06/2012
04:59:27
27.7873
-18.0422
21
1.3
NW FRONTERA.IHI
1148531
14/06/2012
05:00:00
27.7596
-18.0381
26
1.4
W FRONTERA.IHI
1148542
14/06/2012
05:14:10
27.7519
-18.0415
22
1.6
W FRONTERA.IHI
1148536
14/06/2012
05:15:10
27.7306
-18.0264
22
1.9
SW FRONTERA.IHI
1148544
14/06/2012
05:22:16
27.7896
-18.0447
20
1.7
NW FRONTERA.IHI
1148546
14/06/2012
05:27:00
27.7569
-18.0432
23
1.3
W FRONTERA.IHI
1148547
14/06/2012
05:34:31
27.8004
-18.0500
19
1.3
NW FRONTERA.IHI
1148549
14/06/2012
05:34:56
27.7735
-18.0356
21
1.5
NW FRONTERA.IHI
1148559
14/06/2012
05:41:04
27.7853
-18.0509
21
1.8
NW FRONTERA.IHI
1148561
14/06/2012
05:54:22
27.8062
-18.0488
20
1.8
NW FRONTERA.IHI
1148562
14/06/2012
06:01:52
27.7644
-18.0395
22
2.3
W FRONTERA.IHI
1148563
14/06/2012
06:05:07
27.7794
-18.0525
22
2.8
NW FRONTERA.IHI
1148565
14/06/2012
06:06:20
27.7726
-18.0591
23
2.7
NW FRONTERA.IHI
1148568
14/06/2012
07:48:40
27.8015
-18.0680
21
2.1
NW FRONTERA.IHI
Update 13/06 – 13:00 UTC – 2 Earthquakes today after 5 days without any, making a total of 36 earthquakes registered by IGN since 1st June 2012.
– The strongest at 04:57 UTC with a Magnitude 1.8 and depth 25km. At 08:10 UTC a soft movement of Magnitude 0.3 and depth unknown. Both similar location, N Frontera.
Update 10/06 – 15:00 UTC – Following the update containing the document from ULPGC, here is the video, showing the volcano at different depth, bubbles and fish swimming along. Recorded by the Qstar Crew of the Atlantic Explorer.
for more information and updates, go to: http://earthquake-report.com/2011/09/25/el-hierro-canary-islands-spain-volcanic-risk-alert-increased-to-yellow/
With special thanks to Dr. Carracedo (Geovol) allowing us to publish his report and Joke Volta for facilitating.
Dr. Juan Carlos Carracedo Gómez – ULPGC
Forty years after the Teneguía Volcano (La Palma, 1971), a submarine eruption took place off the town of La Restinga, south of El Hierro, the smallest and youngest island of the Canarian Archipelago. Precursors allowed an early detection of the event and its approximate location, suggesting it was submarine. Uncertainties derived from insufficient scientific information available to the authorities during the eruption, leading to disproportionate civil protection measures, which had an impact on the island’s economy based primarily on tourism, while residents experienced extra fear and distress.
El Hierro, 1.12 million years old, is the youngest of the Canary Islands. Located at the western end of the archipelago together with the neighboring island of La Palma, El Hierro rests on a ca. 3500 m-deep ocean bed.
The principal configuration of El Hierro is controlled by a three-armed rift zone system that gives rise to three ridges that extend from the center of the island in a characteristic ‘Mercedes star’ geometry(Carracedo, 1994), and host the larger part of El Hierro’s subaerial eruptions (Fig. 1A).
This triple-armed shape of El Hierro is further enhanced by the scars of several massive gravitational landslides that truncate all three flanks. The collapse of the north flank, that formed the spectacular El Golfo bay with an almost vertical 1400 m-high escarpment, is the youngest landslide of the entire Canary Archipelago with an age of less than 100 ka. Rift zones, however, also continue underneath the sea surface. The south rift stretches as a submarine ridge for more than 40 km (Fig. 1B), indicating that recent submarine eruptions have occurred there as well.
Fig. 1. A. Geological map of El Hierro (from Carracedo et al., 2001). B. colour shaded relief image of El Hierro viewed from above (from Masson et al., 2002). The subaerial and submarine parts of the South rift are indicated.
During the German research cruise Meteor 43/1 in 1998, lava samples were dredged from the submarine prolongations of the southern rift zones of La Palma and El Hierro. El Hierro samples taken close to the present eruptive site (<3 km distant) included fresh picrites and alkali-basalts and variably altered lapillistones and hyaloclastites. Further dredging along the submarine north-west and north-east rift zones during the Poseidon 270 cruise in 2001 recovered fresh alkali basalts from 21 young volcanic cones at depths of 800 to 2300 m together with ocean bottom sediments having a strong volcaniclastic component.
It appears overall that the density of seemingly young volcanoes on El Hierro’s submarine rifts is comparable to that on land, emphasizing the relevance of submarine eruptions during the growth of oceanic islands.
Precursors to the 2011 eruption
Numerous earthquakes were recorded by the Spanish Instituto Geográfico Nacional (IGN) from July 2011 onwards, the greater part of them insignificant from a hazard point of view, but were clearly precursors of a volcanic eruption. In particular, seismicity, initially of low magnitude (M < 3.0) and focused north of the island, increased while migrating southward. The greater part of the hypocentres were initially concentrated within the lower oceanic crust (Fig. 2), at depths of 8–14 km (ca. 200–400 MPa pressure), which is in agreement with pressure estimates from microscopic fluid inclusions in xenoliths from north-western El Hierro and phenocrysts from a recent eruption. The seismic and petrological data are thus in-line with a scenario of a magma batch becoming trapped as an intrusion horizon, near the base or within the subisland oceanic crust. Shifting seismic foci suggest that magma progressively accumulated and expanded laterally in a southward direction, causing a vertical surface deformation of about 40 mm at that time.
During this initial phase, the system remained active but showed no sign of having overcome the resistance of the oceanic crust. Hypocenters thereafter migrated south-east, approaching the submarine prolongation of the active South rift zone. From there, the magma progressed rapidly towards the surface, as indicated by the first time occurrence of shallow (< 3 km) earthquakes on 9 October 2011.
The scenario changed dramatically at about 4 am on 10 October, when the now frequent and strong seismicity (up to M 4.4) ceased and was rather abruptly replaced by a continuous harmonic tremor, indicating the opening of a vent and thus the onset of a submarine eruption.
Fig. 2. Seismic hypocentres beneath El Hierro between 19 July and 10 October 2011. Hypocentres migrated from North towards the South rift zone of the island, where they became shallower (< 3 km). The eruption commenced on 10 October. Most of the time, seismicity remained stable at the base of the oceanic crust (data from IGN, http://www.ign.es/ign/resources/ volcanologia/ html/eventosHierro. html)
The submarine eruption
On October 10, patches of pale-colored water that smelled of sulfur and were associated with dead fish, were found floating one mile south of the coast confirming the opening of a vent on the flank of the submarine part of the South rift zone. The surface expression of this eruption, including green and bright discoloration of seawater, was clearly observed in high-resolution satellite images featuring a large stain(locally known as ‘la mancha’) visible on the surface of the Las Calmas Sea (Fig. 3A). The eruption formed aNE–SW trending fissure outlined by strong bubbling and degassing (Fig. 3B), occasionally 10–15 m high, loaded with juvenile volcanic ash and pyroclasts (Fig. 3C).
However, information on the depth and precise location of the submarine vent was lacking in the first two weeks of the eruption because of the unavailability of adequate means for submarine surveying.
On October 24, the RV Ramón Margalef of the Instituto Español de Oceanografía (IEO) carried out the first survey of the area, previously mapped in 1998 by the Spanish RV Hespérides (Fig. 4A). Comparison of present and 1998 bathymetry outlined a 700 m-wide, 100 m-high new volcanic cone resting at about 350 m depth in a canyon on the flank of the South Rift submarine extension (Fig. 4B). On 4 December 2011, the eruption apparently waning, the RV Ramón Margalef carried out another campaign, detecting significant growth of the volcanic edifice. The initial single eruptive center (Fig. 4A,B) had now evolved to three cones of similar height, with their summit 180–160 m below the sea surface (Fig. 4D), still below the critical value to generate significant surtseyan explosions (about 100 m below sea level).
Lava flows and pyroclasts, confined by the canyon walls, caused the greater part of the erupted volume to flow downslope towards deeper parts of the ocean floor.
Fig. 3. A. Plume of dissolved magmatic gases and suspended matter producing green and bright discolouration of seawater (locally known as ‘la mancha’) commencing on 10 October 2011 and continuing for several kilometres to the south-west before drifting off into the Atlantic (Satellite image by RapidEye). Fig. 3. B. Plumes of gas on ocean surface showing a N–S trend, indicating a submarine eruptive fissure. Inset: Expansion of steam with decreasing water depth (modified from Schmincke, 2004). C, strong degassing with abundant rock fragments generated large ‘bubbles’, some of them 10–15 m-high, bursting to the surface off the nearby village of La Restinga (8 November 2011).
Fig. 4. A. DEM showing the pre-eruptive submarine canyon where the 2011 eruption nested (image taken from the RV Hespérides, 1998). B. DEM of the same area taken on 24 October by the RV Ramon Margalef after the onset of underwater activity. C. Geological map of the submarine eruption from the first DEM obtained on 24 October 2011 by the RV Ramon Margalef. D. Geological map of the same area on 4 December 2011.
Floating stones off El Hierro
Abundant rock fragments resembling lava bombs on a decimeter scale (Fig. 5) and characterized by glassy basaltic crusts and white to cream-colored interiors, were found floating on the ocean surface during the first days of the eruption. The interiors of these floating rocks are glassy and vesicular (similar to pumice), with frequent mingling between the pumicelike interior and the enveloping basaltic magma (Fig. 5B).These floating rocks have become known locally as ‘restingolites’ after the nearby village of La Restinga. Their nature and origin remained elusive at first, with suggestions from the scientific community including: (1) the floating bombs are juvenile and potentially explosive high-silica magma; (2) they are fragments of marine sediment from the submarine flank of El Hierro; and (3) that they are relatively old, hydrated volcanic material. However, none of these interpretations provides a satisfying fit to the available observation since for instance, high-silica volcanism is uncommon on El Hierro, and magmatic minerals (either grown in magma or as detritus from erosion) are entirely absent in the ‘restingolites’. Given that the involvement of highly evolved, high-silica magmatism would have implications for the explosive potential of the eruption, it was important to clarify the nature of the ‘restingolites’ swiftly in order to fully assess the hazards associated with the ongoing El Hierro eruption. Furthermore, should the ‘restingolites’ be shown not to originate from high-silica magma, then unraveling their genesis will most likely provide unique insights into the volcano–magma system beneath El Hierro.
All ‘restingolite’ samples are glassy and light in color and most are macroscopically crystal-free. However, occasional quartz crystals, jasper fragments, gypsum aggregates and carbonate relicts have been identified in hand specimens. X-Ray diffractograms mainly indicate the presence of quartz, mica and/or illite, and glass. There is a notable absence of primary igneous minerals from the XRD data. Microscopic quartz crystals have also been identified and analysed using a field emission electron probe micro-analyser (FE-EPMA), as well as the composition of the glass matrix, which ranges between ~65 and 90 per cent SiO2.
The high silica content coupled with overall low incompatible trace element concentrations, the occurrence of mm-sized relict quartz crystals and the lack of igneous minerals, plus the occurrence of carbonate, clay, jasper and gypsum relicts are all ncompatible with a purely igneous origin for the cores of the floating stones. Igneous rocks on El Hierro do not contain any free (primary) quartz crystals (nor do igneous rocks on any of the other Canary Islands). A potential source of the quartz crystals found in the floating rocks from El Hierro is likely to be the sediments of layer 1 of the pre-island ocean crust. These contain quartz crystals transported from Africa by both wind and turbidity currents and are characterized by a lack of igneous minerals due to their pre-island age.
Fig. 5. A. ‘floating rocks’ observed in October 2011 off El Hierro. B. ‘restingolite’ sample displaying typical features, such as a crust of basalt, primary sedimentary bedding, folding, high vesicularity, and mingling structures. C. hollow basaltic bomb of the late stages of the eruption. D. similar bomb from the Serreta Oceanic Volcano, Terceira, Azores (photograph by Ulrich Küppers).
The floating rocks found at El Hierro are thus most probably the products of magma–sediment interaction beneath the volcano (Fig. 6). Ascending magma mixes with the pre-volcanic sediments and the ‘restingolites’ were carried to the ocean floor during eruption while being melted and vesiculated during transport in magma. Once erupted onto the ocean floor, some of them were able to separate from the erupting lava and floated to the sea surface due to their low density (Fig. 6).
El Hierro Volcano : Green and Yellow alert – eruption continuing + still dead fish above the main vent area
Last update: April 29, 2012 at 11:18 am by By Armand Vervaeck
Update 29/04 – 10:25 UTC – A stain is present in Las Calmas sea this morning. No jacuzzi has been observed. This stain could be the remains of yesterday’s activity. Joke images will be online later today.
Update 29/04 – 10:20 UTC – An amazing picture of the waters of the vent area which was photographed yesterday by Julio del Castillo Vivero. Colored waters with a lot of seagulls having lunch with dead fish
Update 28/04 – 23:48 UTC As written earlier, Julio del Castillo Vivero was invited by the crew of the Atlantic Explorer to sail with them to the vent area. He wrote the following : Hello, very good day with the Atlantic Explorer, the crew of Qstar and the scientists of ULPGC. I was above the volcano! A very special moment for me after many months following the eruption. I saw lots of seagulls above the main vent, eating dead fish, around the size of 10cm that was emerging to the surface. The stain was very clearly visible today from the boat, with a green color, not super strong concentrated as used to, but quite clear.
I didn’t get seasick at all, it was very good. Sea was calm in the morning and then also sunny from midday.
Great day! Great people! Great images!
(ER : strange that there are still dead fish above the main vent – we also noticed on Jokes pictures in the middle of the week that a lot of seagulls were flying above the vent area.
The news coming in from the Atlantic Explorer is even more important as Joke has not seen any action in the sea today, which means that the volcano can erupt without a clear visual sign on the outside. Good to know is that seagulls on the vent area are indicating dead fish and thus erupting material and that a stain clearly indicates action which is more than degassing)
Update 28/04 – 22:55 UTC – 1 additional earthquake today and if not revised , extremely shallow at 1 km. Magnitude 1.0. Time 21:32.Epicenter in El Golfo
Update 28/04 – 13:17 UTC – 1 earthquake since midnight. A M1.4 magnitude quake at a depth of 15 km on this location
– Julio del Castillo Vivero is on board of the Atlantic Explorer. Luckily for him the sea is calm reports Joke (an Ocean swell is even with calm weather often enough to get seasick!). Let’s hope that Julio will have some nice pictures later today. The ROV will not be used today as the people on board of the ship have a bunch of other tasks. Julio has send the image below from the ship a little earlier. It shows the volcano cone at his present depth. We will have to wait until tonight to find out what the colors really mean.
I a direct message to us, Julio writes : ERUPTION STILL ONGOING
Image made by Julio del Castillo Vivero on board of the Qstar Atlantic Explorer today
El Hierro Volcano : Green and Yellow – Pevolca changes alert status from Yellow to Green
Last update: April 20, 2012 at 12:23 pm by By Armand Vervaeck
Update 20/04 – 12:17 UTC
– Joke Volta’s images of today April 20. Calima (African desert dust fog) has finally gone and the pictures are getting more colorful.
Update 20/04 – 07:50 UTC
– NO listed earthquakes since midnight
Update 19/04 – 23:55 UTC
– A third El Hierro earthquake at 18:59 today. Magnitude 0.7, depth 12 km. Epicenter here.
– We have changed the title a littlebit to reflect the current situation. No immediate risk to the island anymore, but still some minor volcanic activity (mainly earthquakes and a little degassing) around the main vent.
Update 19/04 – 15:21 UTC
– It looks like the volcano doesn’t like Pevolca or Mr. Armas !. Almost together with Mr. Armas tweet, the ground was shaking again, a M1.2 earthquake at 13:01 UTC at a depth of 10 km, here
Update 19/04 – 14:09 UTC
– More details have been reported a little later, such as :
* the alert level of the island itself will change from Yellow to Green
* the area surrounding the main vent is downgraded from Red to Yellow (in other words, some limited vigilance remains around the volcano)
* The BIO Las Palmas (Oceanographic vessel), who made some extensive bathymetry last week, measured the depth of the cone at 86 meter.
* Today’s images of Joke Volta
Update 19/04 – 12:09 UTC
– In a short twitter message from the Cabildo de Hierro (office of Mr. Alpidio Armas), the Green Alert of the entire island has been declared by Pevolca. Due to the very slim activity of the last couple of weeks (only faint stains and degassing), the Alert level change seems logical to Earthquake-Report.com
Update 19/04 – 11:03 UTC
– We have noticed one M2.2 earthquake at a depth of 32 km at 08:32 UTC at a very unusual place, which may explain the difference in depth.
Update 18/04 – 21:32 UTC
– ER reader John commented on our remark from this morning that we did not know where CHIE station was exactly. He said : found the location of CHIE it is Latitude 27.72700 Longitude -17.96070 . Information found athttp://www.isc.ac.uk/cgi-bin/stations?listr=Canary+Islands:Europe. Thank you John.
– 1 new earthquake at 14:37 UTC at a depth of 1 km (mostly IGN revises these shallow depths which has not been done so far) ! Magnitude : 0.5. Epicenter here
Update 18/04 – 12:12 UTC
– Joke Volta images of today April 18, a “Calima” day (special regional weather type). Joke hasn’t seen anything special today, but nevertheless she continues to make pictures mainly to have a full series of visuals.
Update 18/04 – 10:52 UTC
– 1 earthquake since midnight. Magnitude 1.4 at a depth of 13 km. Epicenter here
– ER reader Leona has commented that it looks that the thickness of the CHIE HT line has increased since more than 24 hours now. We have the same feeling and have therefore increased the line with the same factor today and 4 days ago. Of course this should not mean anything, as it maybe temporary noise or even instrumental error margin. We neither have an idea where CHIE comes from. El Hierro has a lot of different instruments.
El Hierro Volcano : Yellow alert – Salvamar Adhara spends a couple of hours above the vent “filming”
Last update: March 30, 2012 at 4:19 pm by By Armand Vervaeck
Camera used by SCIC for underwater filming
Update 30/03 – 15:42 UTC – Joke was (of course) in the port at the return of the Salvamar Adhara who spend a couple of hours above the vent. Based on what we have seen in the past weeks and months, we know that if the Salvamar Adhara remains a while on the sea, it is not for water sampling only (takes very short time). Bathymetry was done yesterday by the BIO Hesperides, so bathymetry should be excluded too. So Joke asked Maria José Jurado, the CSIC representative on board, if she had worked with the floating video camera (it is a camera on a rope pulled by the Salvamar Adhara, not a ROV). She said yes, we did.
Joke continued asking Maria José about what she has seen on the camera. She said that she had some interesting material, but she had to analyze it further on. She also said, that when the quality would be good enough, CSIC will send it to the Gobierno de Canarias to publish the video.
Joke also asked : was there still some activity ? She said : Yes, we still see some gases coming out of the vent. Joke continued asking : also gases at the surface ? She said : NO.
We will publish Joke’s images from the boat, spectators, camera on board, a few jelly fish in a while. ER comment : nothing new here of course, at least nothing which surprises us. The jacuzzis we have seen for many days in a row are absolute signs of further degassing. The main question remains, is there still lava coming out of the vent. The last time we know for sure that that was the case was on March 14 when the ULPGC ROV made a video recording of it. The latest bathymetry data from CSIC did tell us that the cone was at 88 meter. But this depth was measured at the end of February ! All frequent El Hierro eruption followers have 1 major question. How deep is the crater rim at this moment ? Is it a coincidence that the Salvamar Adhara starts filming again 1 day after that the BIO Hesperides measured the depth of the Las Calmas sea floor or cone ? Probably yes or probably not. At least we know that fresh erupted lava was seen by the ULPGC ROV on March 14, and there are NO indications that this pattern has changed since then. Does this mean that the depth will be less ? Not necessarily. Let us all hope that the results will be published soon in the website of the Gobierno de Canarias.
Update 30/03 – 09:59 UTC – Joke told us that the Salvamar Adhara has just been spotted at the main vent, probably taking water samples
– On Jokes images (click on the thumbnails below), the main vent can well be seen as well as a far bigger colored area. There is doubt whether this is current coloring or a stain. We go for the stain.
Update 30/03 – 09:59 UTC – Joke just send us a morning report. When walking down the lave fields to La Restinga, she stumbled in a AA lava field (thick sharp lava flowing out of a crater at a slow speed) but fell luckily in a lapilli field (small volcanic stones falling out of the sky during an eruption – more or less like thick ash). It is a little painful but everything is still functioning (including her cameras)
– While driving down with the bus this morning, Joke saw a jacuzzi, but in the meantime he disappeared again
– Joke told us that she saw technicians at the webcam mast ! Let’s hope that they will leave the webcams untouched as we will never see them again in time if necessary ! As politics are against any further “bad news”, we have no hope at all that they will reactivate the webcam.
– 1 earthquake since midnight.
– continuing microseismicity
– NO change in horizontal GPS deformation
Update 29/03 – 22:20 UTC Julio del Castillo Vivero has created a fantastic high resolution panoramic image with 60 images from Joke Volta ! (they regularly share their work). The result El Hierro as a color palette
Picture info : 180 meters above sea level – Taken today (29th March) – Mountain Dácila – Finca José Pérez, locals call it Montaña La Restinga
Click on the image to see this great picture in Full Size.
Update 29/03 – 21:20 UTC – The BIO (Buque de Investigación Oceanográfica) has made a short bathymetry mission stop at El Hierro today during his return trip from Antarctica. Spain has an Antarctica base and during the months November to February, the Antarctic peninsula is merely ice free.
– And to make the day complete, here are the beautiful evening images of Joke Volta
Update 29/03 – 21:04 UTC – The Spanish Army is really good in public relations. IGN needs to take an example on them. In a press report on the Armada Española website this evening, the bathymetry mission was highlighted.
“El buque ha realizado varias líneas de prospección en una cuadrícula de trabajo situada en las coordenadas: 27º 40´N // 27º 30´N de latitud y 18º 05´W // 17º 55´W de longitud, para determinar el punto de mayor altura del edificio volcánico y comprobar posibles variaciones desde el último levantamiento batimétrico.” Human translation : The vessel has done several rectangle routes under the coordinates : 27º 40´N // 27º 30´N de latitude y 18º 05´W // 17º 55´W longitude to determine the highest point of the volcano and check any possible changes since last bathymetry.
– Afternoon images Joke Volta (beautiful colors !)
for more information, and updates, go to:
Camera used by SCIC for underwater filming
Update 30/03 – 15:42 UTC – Joke was (of course) in the port at the return of the Salvamar Adhara who spend a couple of hours above the vent. Based on what we have seen in the past weeks and months, we know that if the Salvamar Adhara remains a while on the sea, it is not for water sampling only (takes very short time). Bathymetry was done yesterday by the BIO Hesperides, so bathymetry should be excluded too. So Joke asked Maria José Jurado, the CSIC representative on board, if she had worked with the floating video camera (it is a camera on a rope pulled by the Salvamar Adhara, not a ROV). She said yes, we did.
Joke continued asking Maria José about what she has seen on the camera. She said that she had some interesting material, but she had to analyze it further on. She also said, that when the quality would be good enough, CSIC will send it to the Gobierno de Canarias to publish the video.
Joke also asked : was there still some activity ? She said : Yes, we still see some gases coming out of the vent. Joke continued asking : also gases at the surface ? She said : NO.
We will publish Joke’s images from the boat, spectators, camera on board, a few jelly fish in a while. ER comment : nothing new here of course, at least nothing which surprises us. The jacuzzis we have seen for many days in a row are absolute signs of further degassing. The main question remains, is there still lava coming out of the vent. The last time we know for sure that that was the case was on March 14 when the ULPGC ROV made a video recording of it. The latest bathymetry data from CSIC did tell us that the cone was at 88 meter. But this depth was measured at the end of February ! All frequent El Hierro eruption followers have 1 major question. How deep is the crater rim at this moment ? Is it a coincidence that the Salvamar Adhara starts filming again 1 day after that the BIO Hesperides measured the depth of the Las Calmas sea floor or cone ? Probably yes or probably not. At least we know that fresh erupted lava was seen by the ULPGC ROV on March 14, and there are NO indications that this pattern has changed since then. Does this mean that the depth will be less ? Not necessarily. Let us all hope that the results will be published soon in the website of the Gobierno de Canarias.
Update 30/03 – 09:59 UTC – Joke told us that the Salvamar Adhara has just been spotted at the main vent, probably taking water samples
– On Jokes images (click on the thumbnails below), the main vent can well be seen as well as a far bigger colored area. There is doubt whether this is current coloring or a stain. We go for the stain.
Update 30/03 – 09:59 UTC – Joke just send us a morning report. When walking down the lave fields to La Restinga, she stumbled in a AA lava field (thick sharp lava flowing out of a crater at a slow speed) but fell luckily in a lapilli field (small volcanic stones falling out of the sky during an eruption – more or less like thick ash). It is a little painful but everything is still functioning (including her cameras)
– While driving down with the bus this morning, Joke saw a jacuzzi, but in the meantime he disappeared again
– Joke told us that she saw technicians at the webcam mast ! Let’s hope that they will leave the webcams untouched as we will never see them again in time if necessary ! As politics are against any further “bad news”, we have no hope at all that they will reactivate the webcam.
– 1 earthquake since midnight.
– continuing microseismicity
– NO change in horizontal GPS deformation
Update 29/03 – 22:20 UTC Julio del Castillo Vivero has created a fantastic high resolution panoramic image with 60 images from Joke Volta ! (they regularly share their work). The result El Hierro as a color palette
Picture info : 180 meters above sea level – Taken today (29th March) – Mountain Dácila – Finca José Pérez, locals call it Montaña La Restinga
Click on the image to see this great picture in Full Size.
Update 29/03 – 21:20 UTC – The BIO (Buque de Investigación Oceanográfica) has made a short bathymetry mission stop at El Hierro today during his return trip from Antarctica. Spain has an Antarctica base and during the months November to February, the Antarctic peninsula is merely ice free.
– And to make the day complete, here are the beautiful evening images of Joke Volta
Update 29/03 – 21:04 UTC – The Spanish Army is really good in public relations. IGN needs to take an example on them. In a press report on the Armada Española website this evening, the bathymetry mission was highlighted.
“El buque ha realizado varias líneas de prospección en una cuadrícula de trabajo situada en las coordenadas: 27º 40´N // 27º 30´N de latitud y 18º 05´W // 17º 55´W de longitud, para determinar el punto de mayor altura del edificio volcánico y comprobar posibles variaciones desde el último levantamiento batimétrico.” Human translation : The vessel has done several rectangle routes under the coordinates : 27º 40´N // 27º 30´N de latitude y 18º 05´W // 17º 55´W longitude to determine the highest point of the volcano and check any possible changes since last bathymetry.
– Afternoon images Joke Volta (beautiful colors !)
Dr. Juan Carlos Carracedo Gómez – ULPGC
Fig. 1. A. Geological map of El Hierro (from Carracedo et al., 2001). B. colour shaded relief image of El Hierro viewed from above (from Masson et al., 2002). The subaerial and submarine parts of the South rift are indicated.
Fig. 2. Seismic hypocentres beneath El Hierro between 19 July and 10 October 2011. Hypocentres migrated from North towards the South rift zone of the island, where they became shallower (< 3 km). The eruption commenced on 10 October. Most of the time, seismicity remained stable at the base of the oceanic crust (data from IGN, http://www.ign.es/ign/resources/ volcanologia/ html/eventosHierro. html)
Fig. 3. A. Plume of dissolved magmatic gases and suspended matter producing green and bright discolouration of seawater (locally known as ‘la mancha’) commencing on 10 October 2011 and continuing for several kilometres to the south-west before drifting off into the Atlantic (Satellite image by RapidEye). Fig. 3. B. Plumes of gas on ocean surface showing a N–S trend, indicating a submarine eruptive fissure. Inset: Expansion of steam with decreasing water depth (modified from Schmincke, 2004). C, strong degassing with abundant rock fragments generated large ‘bubbles’, some of them 10–15 m-high, bursting to the surface off the nearby village of La Restinga (8 November 2011).
Fig. 4. A. DEM showing the pre-eruptive submarine canyon where the 2011 eruption nested (image taken from the RV Hespérides, 1998). B. DEM of the same area taken on 24 October by the RV Ramon Margalef after the onset of underwater activity. C. Geological map of the submarine eruption from the first DEM obtained on 24 October 2011 by the RV Ramon Margalef. D. Geological map of the same area on 4 December 2011.
Fig. 5. A. ‘floating rocks’ observed in October 2011 off El Hierro. B. ‘restingolite’ sample displaying typical features, such as a crust of basalt, primary sedimentary bedding, folding, high vesicularity, and mingling structures. C. hollow basaltic bomb of the late stages of the eruption. D. similar bomb from the Serreta Oceanic Volcano, Terceira, Azores (photograph by Ulrich Küppers).
Image made by Julio del Castillo Vivero on board of the Qstar Atlantic Explorer today
!. Almost together with Mr. Armas tweet, the ground was shaking again, a M1.2 earthquake at 13:01 UTC at a depth of 10 km, 
Comparison in amplitude of CHIE graph El Hierro
