Etna’s paroxysm overview

Since the beginning of this year, Inge B. has kept track of all of Etna’s activity this year and has submitted a summary to keep track of all this for everyone. By now, we have seen a dozen of paroxysms and several other instances of activity at various craters, so it is easy to see people get lost there. For that reason, a table has been made by Inge B. (thanks for that!) which I have sort of converted to wordpress-language.

Etna summit craters map. Image by INGV

Bigger eruptions	Date	Summit craters involved	Characteristics of activity
	9-15 Jan 2013	Bocca Nuova (BN)	Vigorous Strombolian eruption after 3 months quiescence at this crater which had had its first magmatic activity after 10 years again in 2011.
	16 Jan 2013	BN	Strombolian activity
	18 Jan 2013	BN	Strombolian Activity
	20 Jan 2013	New SouthEast Crater (NSEC)	Strombolian activity, first magmatic activity after 9 months quiescence at NSEC
	22 Jan 2013	NSEC	Strombolian activity, more intense than the last ones, bombes rose up to 100 m above crater rim
	28-29 Jan 2013	BN   NSEC	Vigorous Strombolian activity, rumbling noises, to be heard in vicinity of craters Weak Strombolian activity; rhythmic degassing with slight ash content. First time since 12 years, simultaneous activity from 2 summit craters
	30 Jan 2013	BN	Intensive Strombolian activity, launching bombs to about 120 m above crater rim
Paroxysm 1	19 Feb 2013	NSEC	Lava fountaining with production of lava flows, pyroclastic flows, lahars and ash cloud
Paroxysm 2	20 Feb 2013	NSEC	Lava fountaining, lava flows, ash
Paroxysm 3	20 Feb 2013	NSEC	Lava fountaining, lava flows, ash. Second paroxysm that day
Paroxysm 4	21 Feb 2013	NSEC	Lava fountaining, lava flows, ash; 4 paroxysms in 48 hours is very rare
Paroxysm 5	23 Feb 2013	NSEC	Lava fountaining, more intense than before, fountains up to 800 m high, lava flows, ash cloud containing scoriae
	27 Feb – 4 Apr 2013	BN   Voragine (VOR)	Strombolian activity, weak lava fountains continuing through 28 Feb 2013 Explosive activity, first activity of VOR since 1999. Strombolian activity in the night before Paroxysm 6. Still ongoing Strombolian activity with stronger explosions in between, small ash emission, volcanic bombs during Paroxysm 7. Weak Strombolian activity still ongoing; after activity ceased at NSEC at Paroxysm 8, strong explosions at VOR. Weak Strombolian activity still ongoing at Paroxysm 9.
Paroxysm 6	28 Feb 2013	NSEC	Lava fountaining; eruptive fissure opened in the saddle between the Southeast Crater and the New Southeast Crater, lava flows; ash plume, scoriae fallout
Paroxysm 7	5-6 Mar 2013	NSEC	Spattering from new fissure in the saddle between the SEC and the NSEC; lava flows then lava fountains up to 800 m high; intense fallout of scoriae in adjacent towns and villages down to Taormina on the Ionian Coast
Paroxysm 8	16-17 Mar 2013	NSEC	Slow increase of Strombolian activity; lava fountains, ash and scoriae fall, rather violent paroxysm with several loud bangs heard in population centers around the volcano, gas rings; lava overflow, up to 800 m high lava fountains, ash plume 2.000 m high, lightening within the plume; downpour of heavy material, volcanic bombs and big scoriae in the summit area; after explosive activity ceased: small collapses and slides of still hot material
Paroxysm 9	3-4 Apr 2013	NSEC	violent paroxysm, only short time lava fountains, but very loud explosions, noise heard tens of kilometers from the craters, opening of new vents on the NSEC, production of small pyroclastic flows in the summit area (summit area declared “off limits” by the authorities after this episode); ash and scoriae fall in adjacent towns and villages
Paroxysm 10	8-14 Apr 2013	NSEC	Long run-up phase beginning on 8. April with loud Vulkanian (?) explosions (heard tens of km away), some rather heavy explosions with ash emission, followed by a period of Strombolian activity of increasing intensity culminating in lava fountaining on April 12, emission of tephra, ash and lapilli as well as lava bombs, less ashfall though than during Paroxysm 9 and the ones in March 2013; lava flow into Valle del Bove; repeated collapse at NSEC, leading to formation of a depression in the cone lava flow from “saddle” between SEC and NSEC in direction of Belvedere activity also from 2 vents at the base of NSEC on the same day; landslide; small pyroclastic flow two days following of declining activity with some production of weak lava flows
Paroxysm 11	18 Apr 2013	NSEC	From 16 April on some explosive activity at NSEC, ash emissions, small Strombolian eruptions, slowly increasing paroxysm with lava fountaining in the morning of 18. April; eruption cloud with ashfall and lapilli dispersion in direction S-SW; big lava flow into Valle del Bove, two smaller ones from the “saddle” between NSEC and SEC in directions N and S weaker Strombolian activity still ongoing since morning of 19 April
Paroxysm 12	20 Apr 2013	NSEC	Violent activity, ramping up quickly. Fountaining up to 1000 m high with column of gas, ash and lapilli and heavy tephra fall on the east flank. Downpoor of lapilli on the highway Catania-Messina near Giarre. Intensity approximately 30% higher than previous paroxysms.

Sources:
INGV Catania (also for the pictures), reports http://www.ct.ingv.it/en/ (English)
for the 9th paroxysm: http://www.ct.ingv.it/it/component/content/article/11-notizie/news/868
(Italian)
for the 10th paroxysm: http://www.ct.ingv.it/en/component/content/article/11-
notizie/news/875 (English)
for the 11th paroxysm (as per April 20, 2013): http://www.ct.ingv.it/en/ (English) and
http://www.ct.ingv.it/it/component/content/article/11-notizie/news/880 (Italian)

Photo of Paroxysm 10 at the 12th of April 2013. Photo by etnawalk.it

El Nathan

Activity update around the world

Etna has had its ‘paroxysm’ #many. Every eruption is spectacular, but when they are so frequent it gets easier to focus on what is different with every eruption. Bruce Stout and Newby noted that the activity lasted much longer than previously in this series of paroxysms. Why this is, is off course a mystery, but maybe as time progresses we will find out if this is again some kind of new behaviour for Etna. For now, I don’t think many people mind that Etna keeps doing these things, since the eruptions are not much of a nuisance to the people living around it (at least, not more than usual with Etna’s eruptions), but are nice to watch for everyone.

Mr. Behncke of the INGV in Catania has written a nice summary / eyewitness report of the activity, which can be read on his Flickr-photostream. The question is indeed if this longer-lived activity can still be called a paroxysm.

Webcam image of today’s paroxysm. Image by INGV

Inge B. pointed to some images released by the INGV showing the Italian island of Vulcano, which seems to show a bit of unusually strong fumarolic activity.

Eolian island of Vulcano. Image by INGV.

The island is known to be volcanically active in recent history. The last eruption has been recorded in 1888 at the Fossa cone. The cone can be seen in the webcam image above. The Fossa cone has been the main center of activity in the last centuries, and fumarolic activity and gas emissions are ever-present to some degree at the Fossa cone. Sometimes, the activity peaks, like for example in 1985 and 1990, which shows that the town at the bottom of the Fossa cone is still under constant threat.

The Vulcanian town of Volcano Porto at the base of the Fossa cone. Image by INGV.

The island of Vulcano is off course most famous for being the place that gave volcanoes their name. In Greek and Roman mythology, the god Hephaestus, or Vulcan, was the god of fire and was thought to have its workshop below the Eolian island, leading to the frequent release of fire from the mountains on it. It is also the type locality for one of the 5 main types of magmatic eruptions; Vulcanian activity. This type of activity is characterized by viscous magma, andesitic to dacitic, that frequently erupts explosively and generates volcanic blocks and bombs that rain down on the surroundings. For comparison, Sakurajima is the best example of Vulcanian activity in recent years. The area where the volcanic blocks and bombs rained down during the 1888 eruption on Vulcano is where the town of Volcano Porto is now built, leading to the constant threat mentioned before if Vulcano decides to really wake up and go back to the behaviour the ancient Romans knew it for.

Meanwhile, Tolbachik seems to be re-thinking it’s decision that the eruption has now lasted long enough. Strong seismic activity has been recorded, together with strong gas-steam activity and a big thermal anomaly was seen on satellite images. Estimates of the erupted volume are well above 1 km3, so this number continues to rise for now.

Also, Granyia noted that the Chilean volcano Lascar had seen its alert level raised to Yellow, after reports of small explosions and some ash in steamclouds. Looking at the webcam, it looks like some glowing can be seen. Sernageomin reports (.pdf, in Spanish) that during a helicopter flyover, temperatures above 600 degrees celcius were measured in the crater using a thermal camera, which confirms the reports of glowing at night.

Lascar webcam image. Image by sernageomin.cl

El Nathan

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Post update by Spica:

The Sheepy Dalek bar is open and Alan sent in another Evil Riddle:

I shan’t beat about the bush - a real spiny subject this, but at least you wouldn’t need a tv aerial!

What am I?
What are my special properties?

Good luck and have fun!

Alan C.

El Hierro still going strong and a riddle

Some parts (?) of El Hierro experienced a short power outage last night, This was also viewable on the solitary working webcam at the moment which was noticed by some regulars. Quite some earthquakes Mag. 3+ and even some Mag 4+ have been recorded.

chryphia created a new plot which shows the action going on:

Quote:” Here is another 3D plot, no overlays this time .
It shows the current swarm and the older earthquakes in two separate color scales. I wanted to see where the central El Golfo bay earthquakes are located exactly: they are slap-bang in the middle of the northernmost, deep (magenta) swarm, barely visible in this plot. This is where all the other swarms originated, thus I am worried that there is even more magma arriving now. For a good 2D view look at http://www.01.ign.es/ign/resources/volcanologia/html/eventosHierro.html

“

Earthquake Report has a link to an image of all the spectrograms of this crisis stitched together: http://jdcv.es/Media/Hierro/2013/CHIE_upto2903_B.jpg
from http://earthquake-report.com/2011/09/25/el-hierro-canary-islands-spain-volcanic-risk-alert-increased-to-yellow/
Noted by Jim Ludwell.

Earthquake-report.com also used chryphias plot without giving her credit which I personally find absolutely not OK.

Many can explain the current crisis much better than I ever could. So here there are some comments to good to be lost:

GeoLurking says: March 29, 2013 at 04:37
Quote: “when this whole thing was first bopping along, the gov was reticent about doing anything until it became clear that Mag 4.0 quakes were a possibility. Mag 4.0 was where they flinched and it was clear that something could shake loose and hurt somebody, so that was about when they started taking precautions.

One thing that Carl noted was that the seismic gear was probably not set up for volcano monitoring and that IGN and Pevloca had to undergo a paradigm shift from watching for potential landslides to watching for volcanic activity. Outside experts were consulted and new gear was brought in. (the temporary seismic stations and the additional GPS units.)

Now 4.0s seem to be regular fare. It doesn’t lessen the hazard. A 4.0 still releases considerably more energy than a 3.0.
For now, the most immediate threat is still the same. Something getting shaken loose from the bluffs.

Then there is how it plays in the volcano scheme of things. If the quakes are being caused by magma forcing it’s way through the rock, the best that I can envision is a series of normal mode faults. A 3.0 has a maximum displacement of 0.275cm. A 4.0 has 1.17cm. That’s would be a crack about 4.3 times the size of the 3.0. Keep in mind that this is probably pushing the Wells-Coppersmith equations a bit outside of what they were intended for, but it does illustrate the differences in the two quake sizes.

If it is magma pushing through rock, what has happened is that the hoop stress of the rock around the area of the magma has been exceeded and the magma breaks open the rock with what is probably a mode 1 crack. This realm of math is beyond me, so I rely on the Wells-Coppersmith crutch to provide some level of understanding. Going whole hog, and looking at the rest of the formula… a normal mode fault of Mag 4.0 has a down dip rupture width of 1.82 km. If intruding magma is what is at play, it could conceivably make a path about half of that width higher each time it happens. If that starts to show up in the quakes…“

Read the whole comment by clicking it.

Renato Rio says: March 29, 2013 at 13:34
Quote: “The PEVOLCA maintains civil protection measures in El Hierro and follows the evolution of the phenomenon
03/29/2013 … 12:38 – Ministry of Economy, Finance and Security
* The data indicate that the seismicity has migrated to the southwest in the last 24 hours. The direction of the Civil Protection Plan for Volcanic Risk (PEVOLCA) maintains civil protection measures that were taken last Wednesday in El Hierro given the magnitude of the seismicity that is occurring to the west of the island.
As you may recall the steps taken by the management of PEVOLCA are the following:
Disabled the lane closest to the on the output side of Frontera tunnel closing the stretch of road between the HI 50 between Cruce de la Tabla and Sabinosa and the access road to the Playa La Madera, the Pozo de la Salud to the confluence with the HI 503. It is important to avoid transit through these areas because of the risk of landslides.
Accesses are opened to the Ermida de los Reyes and the southern Sabinar area, HI 400
Meanwhile it is maintained the yellow alert of information to the population in the area bounded by the HI 500 and the height of the Pozo de la Salud to the south, at the confluence of the HI HI 500 with 400 in the crossroads known as El Tomillar.
As for the seismo-volcanic phenomena, earthquakes located in the last 24 hours have migrated slightly to the southwest over previous days, reaching the west of Orchilla between 15 and 20 kilometers deep at a distance from the coast between 12 and 15 kilometers. The values ​​of CO2 in the atmosphere have increased but are still within normal parameters.
The direction of PEVOLCA wants to remind you that they are doing continuous monitoring and real-time of thr phenomenon, so any change in the pattern of movements that imply risk will be communicated immediately. It also recommends considering the advice of self-protection in the event of earthquakes, known to all, and can be viewed in http://www.gobiernodecanarias.org/dgse/descargas/sismo_hierro/autop_sismo.pdf“

Bruce Stout did some drawings:
To understand the images one needs to read Bruce’s comment and all the follow up’s by Peter Cobbold and Bruce. Bruce Stout says: March 29, 2013 at 14:23

Richie Lee gave us a link to a TV station in the Canary islands where some news might be broadcasted. Canary TV: They don’t stream everything but most live newscasts are available. The last few days they have had coverage of the El Hierro activity.

http://www.rtvc.es/television/enDirecto.aspx?canal=tv

I personally do not think any eruption is imminent, but it is interesting to watch. And in case you need the links again, just holler.

Spica

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A riddle for tonight, while we are watching what is happening in El Hierro and Iceland!
Same as last week …. so link the each clue to a volcano and spot the red herring ….

1 point for each volcano and 1 point for each red herring (with brief explanation)

All solved … Red herrings in bold … Answers ..

No 1 Big Ben

No 2 Mount Churchill

No 3 Hekla

No 4 Glen Coe

No 1 – 2745; Furious 50s; New York landmark; Augustus Pugin; SOLVED
No 2 – Bobsleigh run; Radiocarbon; Battle of Stepney; Infantry Tank; SOLVED
No 3 – 1750; 1104; 1864; 4892; SOLVED
No 4 – 1692; Easter Island; Cauldron subsidence; Harry Potter; SOLVED

Points .. Well done all

Kelda  4 points

Volcanic 2 points

Stephanie Alice Halford 1 point

Inge B 1 point

Kilgharrah

El Hierro’s western part on “Code Yellow”.

Pevolca reacted on the earthquake series that happened yesterday and set the western part of the island to a “yellow alert zone”. All this happened in agreement with the government of El Hierro.

The dramatic events on CHIE yesterday.

Full report (in spanish) and a short excerpt for your information: Closing the lane of the tunnel closest to the exit in Frontera, closing the length of road HI-50 between ‘Cruce de La Tabla’ and ‘Sabinosa’ and the access road to ‘Playa La Madera’, of ‘Pozo de la Salud’ until the crossing with road HI-503.

Yellow informative alert for the population at the zones limited by HI-500 at ‘Pozo de la Salud’ to the South, en the crossing between HI-500 with HI-400 at the crossing known as ‘El Tomillar’.

The best sites to get the newest information are:

• Earthquake report
• El Hierro blog from Manfred Betzwieser in German.

Those 2 sites are not normal blogs like VolcanoCafe publishing a full post every few days but they report close to the “action”.

dfm created a brilliant plot and explained it:

This is the update till 18h43 today

Today there were a number of strong (for El Hierro) earthquakes with quite a few over mag 4 which is quite rare.

In the list of earthquakes you will notice that for the strongest earthquakes there is only one event of similar magnitude (4.6) and that in all the events with mag >=4 (16 out of more than 17000 !) 5 came to happen today.

(The ful list of quakes dfm used can be found in his comment on “Watching Hekla“: dfm says: March 27, 2013 at 21:15 )

Without wanting to be fear mongering, I find this situation unprecedented. If you add this to an also unprecedented trend in the upward component of the GPS, this situation begins to pose a number of questions. Happily (if one may say) the bulk of the seismicity is located at sea and not on the island emerged part.

Meanwhile here is the earthquake update for the period since March 26th 8h18 and 27th @ 18h43. It includes the 4.6 quake.

The color of the quakes is linked to their position on the list (more than 1200 events since March 18th).
I will probably change this next time as the color scale loses its interest.

It is interesting to note in the time-lapse animation that there are first some cluster of quakes in the previous parts, leading to a hypothesis of a “sill” of sorts or at least to an accumulation of rock breaking in the same place. Then most of the “strong” (meaning over Mag 3 ) quakes seem to appear on the border of that cluster (look at 0’20”). Could it be that there was some renewal of magma arrival (a new “bolus”) and that the constraints bring some rock breaking on the limit of the previous cluster. I will only repeat that these new events happen in a zone previously devoid of earthquakes.

The 4.6 event can be well see at 00’49″ on the center-left part of the plot, over the 27,6 mark on the abscesses.

Do look at the end of the video in the zoom sequence (1’22″ and 1’28″)

On the right side of the colorbar the terrain elevation scale is shown. Magnitude of the events (sorry I stopped at 4 !) is shown on the lower part of the plot.

Data from IGN and NOAA, made on Gnu Octave.

Peter Cobbold noted: Bearing in mind the GPS stations are ~15km away from the swarm centre the 100mm uplift in ten days is unusually high for Hierro. Previous swarms have been co-located with the GPS stations and resulted in smaller uplifts over longer periods,IIRC.

Yesterdays trend. El Nathan did not really see a tendency of the earthquakes coming closer to the island.

In case more earthquake swarms happen, there is the possibility of rockfall (or maybe even landslides). At the very moment an eruption on the island is unlikely in my eyes. (Personal layman opinion.)

Links to watch El Hierro (besides the cams) are to be found on Wonder what Bob is up to.

HEKLA
Lets not forget some here like Jamie and Islander are still on a 24hr Hekla watch.
Hekla is still on alert level yellow but not all too much happened close to it yesterday.
Islander also informed us:
Hekla “news service” latest scoop : IMO has brought back online the fourth (4) SIL for monitoring the greater Hekla area. These are HAU from the west, fedgar. (http://hraun.vedur.is/ja/oroi/fed.gif) from the north, VAT from the east and MJO from the south. Nothing EQ wise then can escape the sharp eyes of the IMO staff. http://hraun.vedur.is/ja/oroi/index.html
Fedgar is not on this overall map.

Again the Hekla links:

• Hekluvöktun Hekla Data
• Hekla GPS
• Borehole Strain and Hekla seismicity
• Website on Hekla ( Swedish)
• Jarðskjálftar
• Seismic stations close to Hekla

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Other sites have the information about the earthquakes too but dfm’s plot is only on VC.

Spica

Watching Hekla

Kobba informed us that the alert level at Hekla was raised to yellow:
“http://www.dv.is/frettir/2013/3/26/ovissustig-vegna-jardhraeringa-i-heklu/
Some things are up with Hekla….Alert levels raised to yellow due to “peculiar unrest” in Hekla”

“Translated: National Commissioner of Police and the Commissioner of Hvolsvöllur declare confidence level of civil eruptions of Hekla

The Icelandic Meteorological Office has informed the National Commissioner for Civil unusual Seismicity at Hekla. IMO has also increased monitoring points Hekla to yellow due to air traffic, which means that the volcano show unusual activity.

Uncertainty level civil means for increased monitoring of the actions of that at a later stage could lead to health and human safety, environmental or building will be threatened. To describe the level of uncertainty is part of the processes in the organization of civil protection to ensure formal communication and information. Uncertainty level is declared to inform the appropriate emergency and is a process in civil emergency planning and the lowest of the three.

In light of this, will the National Police Commissioner and the Commissioner of Hvolsvöllur warn people on journeys while Hekla uncertainty level is valid.”

http://www.ruv.is/hekla Image taken on March 18th.

• Hekluvöktun Hekla Data
• Hekla GPS
• Borehole Strain and Hekla Seimicity
• Website on Hekla ( Swedish)
• Jarðskjálftar
• Seismic stations close to Hekla

Erik Klemetti has the news too on his blog Eruptions. Alert Status Raised at Iceland’s Hekla

Icelanders photo

Icelander: “VC staff photographer has sent us this test image. Expect more of it in action, whenever that will be. Enjoy. http://i50.tinypic.com/2e5v5ax.jpg

Yes, these were for express use of VC and be used when Hekla became “imminent”  Copyright lies with the photographer. Here is another angle from October last year.
“http://i49.tinypic.com/1z9jsw.jpg ”

Here are plots by chryphia of Hekla´s local earthquakes from 2000 until today.

Hekla seismicity 2000 to 2013

The last two earthquakes from the listi were on Mar 21st and 23rd and were located in the small group at 10 km depth:

Hekla seismicity 2000 to 2013, view facing West. The depth axis is compressed about 2x in order to get the Moho layer (http://www.seismo.helsinki.fi/mohomap/) into view. The topology is from geodas-design-a-grid.

Icelanders image and his explanations: Quote: “for these watching IMO uncorrected strain charts – this is how they appeared in April 2012, the month I thought it whould go off, so nearly 12 months old.
Notice the large drops at HEK (other stations were not operating then). Graph is stretched or schrunk, to get “same unit scale” (a feature or the Original IMO charts I do not like, is that their scale is NOT constant, but fortunately they are scaled, so here goes). http://i45.tinypic.com/ziopkw.jpg
Yess, top graph is BUR, same days as HEK (lower). I have the days before these too. Including a big quake of international standards, first a meeting, then more plots (Yes these are mine “Scale-ings”!)”

Remember Carl wrote a lot of posts on Hekla, you can find them here.
Spica