Volcano Report fr/E. Klemetti

Eruption Update: Copahue, Poás, Sinabung, Kilauea, Holuhraun and Italy

Webcam image of Copahue in Chile, seen on October 16, 2014. A small steam-and-ash plume can be seen along with deposits of fresh, dark grey across on the volcanoes slopes. Image: SERNAGEOMIN.

I apologize for being missing for the last week. The big Geological Society of America meeting is next week in Vancouver BC and not only am I giving a talk and co-chairing a session, but two of my students are presenting posters. Needless to say, things have been busy. My talk centers on what zircon can tell us about the storage conditions and source magmas across the Cascade Range. I have zircon data from four Cascade volcanoes: St. Helens, Hood, South Sister and Lassen, it is a great chance to see how the differences in different parts of the Cascade arc might influence the composition of zircon. My two students are both presenting on their pieces of the Lassen Volcanic Center project, so we’ll be presenting over 800,000 years of zircon data.

Not only that, but I also built a volcano on the Denison campus, so if you missed the video of that, check it out.

So, without further ado, here’s some brief updates around the world of volcanoes:

Iceland

The Holuhraun lava field eruption is now one of the largest continuous eruptions in the past few centuries in Iceland here in its second month of activity. Lava flows and fountains are continuing on the plain between Barðarbunga and Askja while the Barðarbunga caldera itself is still subsiding at a rate of 30-40 cm/day. So far, that subsidence is over 0.75 cubic kilometers of lost volume below the caldera floor and large earthquakes are still occurring near the caldera. The biggest danger from this eruption so far has been the copious sulfur dioxide emissions that continue to cause problems for people in Iceland (depending on the winds). If you want to see some stunning images of the eruption, check these out — especially some of the overhead shots of the lava flows. Also, there might be something lost in translation, but Haraldur Sigurðsson make the odd prediction that the eruption would end on March 4, 2015 — a little too specific for my tastes.

Indonesia

Sinabung has entered back into a phase of more intense dome-collapse pyroclastic flows. This crisis at Sinabung has now lasted well over a year and local residents are running into problems with access to food and water. Not only that, but rainfall around the volcano combined with these eruptions has caused the threat of volcanic mudflows (lahars) to increase dramatically. The loose volcanic ash and debris is easily remobilized when heavy rains occur, creating a concrete-like slurry that can be very damaging and dangerous. On the opposite end of the spectrum, some of the pyroclastic flows have also triggered fires in the regions around Sinabung.

Chile/Argentina

Copahue has had a number of moderate explosive eruptions over the last week that prompted some minor evacuations of herders near the volcano. This is the third bout of explosive activity at the volcano since it became restless at the end of 2012. The alert status at Copahue is Orange and if you want to check out what is up there, use the SERNAGEOMIN webcam.

Costa Rica

Poás experienced a number of explosions as well. These mainly steam-driven events closed off the summit of the volcano to tourists for a few days, but access has been reopened after signs of the volcano settling down again – although the overall unrest continues. Be sure to check out the OVSICORI time-lapse video of the explosion as well.

Hawaii

The lava flow headed down the slopes of Kilauea towards Pahoa is still continuing to crawl forward. Now the flows are moving at ~25 meters/day, but the threat still remains for the flows to reach houses and roads if it continues to flow. The current estimate has the flow reaching Apaa Street in Pahoa around November 1. So far, the only damage the flows have caused is to vegetation.

Italy

In case you missed it, be sure to read David Wolman’s coverage of the appeal for the Italian geologists convicted in the aftermath of the L’Aquila earthquake. It still amazes me how much the Italian judicial system is willing to believe in charlatans and find scapegoats for an act of nature.

from:    http://www.wired.com/2014/10/eruption-update-copahue-poas-sinabung-kilauea-holuhraun-italy/#more-1601379

Eruptions at Mayon Volcano in Phillipines

New Eruptions at Mayon in the Philippines Prompts Evacuations

The conical summit of Mayon in the Philippines. Paths of previous lava flows and pyroclastic flows can be seen on the steep slopes of the volcano.

Quick post before I take off for the Department of Geosciences Fall Field Trip. If you’re looking for the current status of the eruption in Iceland, be sure to check out the Icelandic Meteorological Office.

However, today’s post is about the renewed activity at Mayon in the Philippines. It appears that lava is now actively extruding at the summit of the volcano, producing rock falls of incandescent blocks of lava. Seismic activity has increased dramatically over the last week and the style of earthquakes suggests to geologists at PHIVOLCS that magma is ascending inside the volcano. They have increased the alert status at Mayon from 2 to 3 (on a 5 level scale) and say that the potential for a “hazardous eruption” within weeks is high.

What this means in a practical scene is that over 24,000 people are now being evacuated from an 8-km radius around Mayon. The Philippine government is establishing refugee camps for the first evacuees* and readying more if the situation at the volcano suggests that a larger evacuation is needed. The largest hazard posed by Mayon is that of pyroclastic flows generated by the collapse of the new lava dome forming at the summit (or possibly from any explosive eruptions that might occur). Mayon is definitely one of the most active volcanoes in the Philippines — and even when it is not in an active eruption period, steam explosions at the summit can be deadly. The Philippine government is watching the activity closely to determine if and when more evacuations are needed.

As I mentioned with the eruption of Rabaul, this activity at Mayon has the potential to have much more direct consequences on people than the activity in Iceland. In the Western Pacific and Southeast Asia, hundreds of thousands of people live within a few tens of kilometers of these potentially highly explosive volcanoes. At Mayon, that number is over 250,000 people within 10 kilometers! Keeping a close eye on these eruptions is definitely a necessity to protect those lives.

* AUTHOR’S NOTE: This article from the Philippine Star quotes a PHIVOLCS volcanologist as saying that Mayon is “overdue” for a large explosive eruption. This is based on a grand total for 2 prior eruptions in 1814 and 1897. I wouldn’t believe this sort of talk as 2 data points cannot be used to set such a pattern, even if it existed.

from:    http://www.wired.com/2014/09/new-eruptions-mayon-philippines-prompts-evacuations/#more-1565563

Hawaii, Iceland Volcanic activity

Eruption Update: New Fissure Eruption Starts Closer to Vatnajökull in Iceland, Kilauea Lava Flow Threatens Homes

Lava fountaining in the second fissures in the Holuhraun lava field, Iceland, seen on September 4, 2014. Photo by Image from  Jonni Productions video.

Two updates for today, dominated by action at the two most famous hotspots on the planet:

Iceland

A new fissure started erupting this morning to the south of the current activity in the Holuhraun lava fields in Iceland. These two new fissures are closer to the Vatnajökull ice cap (just 2 km north of its edge), so concern is growing larger than the eruption will start happening subglacially, potentially causing jökulhlaups (glacial outburst floods) as the lava erupts under the ice. The Icelandic Meteorological Office is also reporting that the cauldron (depression) in Dyngjujökull, the northern part of the ice cap, is getting larger and more pronounced, both of which are signs that more heat is being felt at the bottom of the ice (possibly caused by eruptions under the ~300-350 meters of ice). Check out these images of the cauldron on the ice surface. The most serious ramification is the potential for more explosive style of eruption if water can mix with the lava.

So far, the vigor of the eruption at the new fissures is lower than the other active fissures, where lava fountains (see above) are reaching over 100 meters into the air. Be sure to check out these great images of the lava fountaining, spatter cones and lava flows of the larger fissure field. The older lava flow field now covers just over 10 square kilometers. Watch this video to see what it’s like to get up close and personal with the lava flows right now.

 

The steam plume from the eruption is reaching 4.5 km (15,000 feet) and the sulfur dioxide plume is beginning to spread beyond the region right around Iceland. Changes in the weather patterns around the island suggest that the plume may spread enough to reach Europe, although the only possible ramifications of that might be some sulfur odor across the British Isles.

Hawai’i

Lava flows approaching KKK Homesteads on Kilauea's slopes, seen on September 3, 2014. Photo by Hawaii Volcano Observatory / USGS.

Meanwhile, in Hawai’i, lava flows are threatening homes on the slopes of Kilauea (see above). The USGS has raised the alert status at Kilauea to its highest – Warning – after lava flows exploiting a ground crack moved downslope and re-emerged near the Kaohe Homesteads. This lava flow was able to move so much further downslope thanks to the insulating nature of the ground crack, keeping the lava hot enough to flow longer and faster. At the current rates of flow, the lava could reach the Homesteads in 5-7 days if it continues to exploit the ground cracks. Currently, the lava flows are burning their way through the forested lands on the flank of Kilauea. The Hawaii Volcano Observatory has an excellent collection of images of the lava flows, showing how it is advancing towards the homesteads. Although these lava flows aren’t a hazard for people as such, previous lava flows have destroyed entire communities on the slopes of the volcano.

from:    http://www.wired.com/2014/09/eruption-update-new-fissure-eruption-starts-closer-to-vatnajokull-in-iceland-kilauea-lava-flow-threatens-homes/#more-1528801

On Yellowsotne & Katia

How to Keep Things Hot at Yellowstone and Katla: Just Add Water

A large fumarole (steam vent) in the Norris Basin at Yellowstone. The steam escape the hydrothermal system here might be over 400C. Photo by Erik Klemetti.

Two volcanoes that get the interwebs all hot and bothered have made the news in the last week. First, Katla in Iceland produced some glacial flooding (jökulhlaups) that followed some earthquakes. Second, over at everyone’s favorite caldera, Yellowstone, there has been a lot of buzz over roads melting due to heat from the volcano. Now, as odd as it might seem, these two events are connected by the same process: geothermal (and hydrothermal) activity. When it comes down to it, most volcanoes are sitting on big heat sources. One way to lose the heat is by erupting, but probably the most important way to lose the heat is by the circulation of water in the crust. This water help keep things hot by efficiently moving heat generated by the magma that might be 5-6 kilometers (or more) below the surface and bringing it up to the surface — all of this happening when there is no threat of an eruption.

When you examine the history of a volcano, you’ll quickly see it spends much of its existence not erupting. However, during those periods of quiet between eruptions, there is plenty going on beneath the volcano. The magma is cooling and releasing heat and fluids in the surrounding rocks, causing the development of a hydrothermal system above the cooling magma. This is usually the top 5 kilometers of crust above the magma, where cracks in the rocks can help hot fluids rise from the magma and cool fluids (like rainwater or snowmelt) percolate down into the crust and heat up. So, how hot does it get under a volcano? Well, by examining the exposed innards of extinct volcanoes, we can see how much alteration the rocks and minerals have experienced. This is an important step in understand how certain valuable ore deposits, like porphyry copper, form above bodies of magma under volcanoes.

Looking at these zones of hydrothermal alteration, it is clear that the subsurface temperatures get hot — upwards of 300-500°C even multiple kilometers above any cooling magma body. Now, that heat isn’t getting there by conduction alone. Rock isn’t a very good conductor, so heat won’t travel far. However, if you heat up water traveling through cracks in the rock, you can transport a lot of heat upwards. That’s because water has a high heat capacity – think about how the Gulf Stream brings warm water from the tropics to the North Atlantic to keep Europe warm. That is what allows all the alteration to occur and for hydrothermal systems to form. These hydrothermal systems are constantly changing based on the seasons (thanks to changing access to water percolating into the crust), seismicity that opens and closes cracks and yes, even magma moving. However, most of the time, the changes in the system are merely due to new routes these hot fluids take to reach the surface.

What are the manifestations of these hydrothermal fluids? You see some of them at most active volcanoes: steam vents (fumaroles), hot springs, geysers, mud pots. Each is a different way heat escapes the ground. Steam vents tend to be the hottest, releasing steam (with other volcanic gases) at temperatures of 300-500°C. Geysers are explosions of superheated water, so they will be ~100°C. Hot springs and mud pots tend to be much cooler, with temperatures usually 20-70°C, depending of the vigor of the spring or geyser.

Glacial flooding from underneath Mýrdalsjökull in Iceland, seen at Múlakvísl.

So, even moving water through the crust can bring a lot of heat upwards and that is common at most volcanoes — as are changes in the hydrothermal system over time. So, what is happening at Katla and Yellowstone?First, at Katla, the hydrothermal system works underneath a large ice cap (Mýrdalsjökull). Especially during warmer months, more water can percolate into the crust, causing changes in the hydrothermal system (which, by itself, can generate earthquakes). If more heated water and steam is allowed to reach the surface, then more ice can melt and pond until it is catastrophically released as a flood. Reports from the Iceland Met Office support this idea – the waters are warm as they come out from under the glacier. However, unlike an eruption-driven event, the melting isn’t accompanied by a continuously increasing number of earthquakes that would betray magma moving. So, the most likely explanation for these floods is increasing melting due to changes in the hydrothermal (geothermal) system, not an eruption. These sorts of floods have happened before during this time of year at Katla, sometimes more dramatic than others.

Now, at Yellowstone, we have a different manifestation of the same thing. The news has splashed images of melting roads on Firehole Lake Drive in an area with intense hydrothermal activity. The usual suspects (e.g., the Yellowstone disaster groupies) want to say this is evidence that an eruption is in the works. Well, again, sorry to disappoint the lunatic fringe, but it isn’t. Instead, this is a sign that the hydrothermal system under Firehole Lake Drive has shifted some — maybe due to the constant seismicity that gently shakes Yellowstone, maybe due to the water table, maybe even due to the road itself — and now heat is coming up directly under the road. Now, asphalt like that can melt at temperatures as low at ~50-70°C, so well within the range of most hydrothermal features. Measures of the road surface by NPS workers are ~70°C, so we’re well within the range of temperatures needed to melt the road. Just move where that hot spring or fumarole is coming up and boom, you have heat under the road, melting it.

 

Bumpass Hell, the hydrothermal area near Lassen Peak in California. Photo by Erik Klemetti.

I’ve seen roads get damaged or destroyed by changing hydrothermal vent locations around Lassen Peak (see above) and in Rotorua in New Zealand — both places with active hydrothermal systems and shockingly, no giant eruption following the damage to the road. There are many places in Yellowstone itself where parking lots have been closed due to changes in the location of hydrothermal vents, causing them to melt and collapse due to the increased heat. This is by no means a harbinger of doom but rather exactly what we might expect in a place with an vigorous hydrothermal system. In a sense, Yellowstone is less of a “supervolcano” than a “super plumbing system” moving fluids around the crust.

Now, the real hazard from changing hydrothermal systems at Yellowstone is not a giant “super-eruption”, but rather much more dangerous (because they are far more likely) hydrothermal explosions. These are caused by superheated water and steam getting trapped and then releasing catastrophically. These can happen without warning and if you’re too close, you’ll be covered with boiling water and debris from the explosion. As usual, the place to look for the most accurate information about potentially hazards at Yellowstone is the Yellowstone Volcano Observatory. If they’re worried, so should you. They monitor the temperatures of these hydrothermal features across the caldera and if there are widespread changes, they examine them to see if they could be related to magma moving (least likely) or merely the shifting of the hydrothermal system (most likely).

So, remember, the increasing heat at the surface near a volcano isn’t always from magma — it can merely be caused by changes in how hot water and steam move through the crust. It is one of the ways that volcanoes can dissipate the heat released by magma cooling underground and more importantly, it doesn’t have to be magma that is trying to erupt.

from:    http://www.wired.com/2014/07/how-to-keep-things-hot-at-yellowstone-and-katla-volcanoes-just-add-water/#more-1252261

Ubina Volcano in Peru Activity

Peru Volcano Rumbles to Life, Evacuations

AFP Photo / September 2013

Heather Callaghan
Activist Post

By now, news has reached every end of the globe of the 8.2 magnitude earthquake in northern Chile last night (North American time). Chilean coastal cities were on tsunami alert, as there was detection of an ocean wave generated – but those warnings have now been lifted.

The epicenter of the earthquake affected fault lines in a “Ring of Fire” of volcanoes. Southwestern Peru was also affected by the earthquake and one volcano started to spew ash on Tuesday.

Ubina has not exploded in forty years, but signs of spewing ash skyward caused authorities to evacuate villagers as a precaution
Yahoo reports:

The volcano in southwestern Peru blasted back to life causing about 60 villagers from Querapi, near its base, to be relocated Saturday, Ubinas town mayor Pascual Coaquira said.

“We are readying a shelter for refugees from the blasts,” he added Tuesday, noting that the whole Moquegua region was on alert.

The mayor said that the ash had been raining all day on Tuesday, and residents were having trouble breathing. The ones struggling with respiratory distress were given masks to help breathe.

The geological and mining agency for Peru noted unusual lava build-up in recent days and warned that local residents should prepare for more evacuations.

from:    http://www.activistpost.com/2014/04/peru-volcano-rumbles-to-life-evacuations.html

Pacaya VOlcano Erupts in Guatemala

Guatemala’s Pacaya Erupts

A Terra image of the plume from the March 2 Pacaya eruption. Image: NASA /

Terra image of the plume from the March 2 Pacaya eruption — the brown plume spreading to the west. Image: NASA / Nahum Charazza – Twitter.

Over the weekend, Pacaya in Guatemala got everyone’s attention with a moderate explosive eruption. This explosion was nothing compared to the really big bang we saw last month at Indonesia’s Kelud, but it was enough to cause some real concern in Guatemala. The March 2 eruption produced a fire fountain that reached 800 meters tall at the summit (check out the image below) and an ash plume that topped out at ~3 km (10,000 feet) above the sea level (so ~2.4 km / 8,000 feet above the volcano). The day was clear, so we got a nice shot of the eruption on the Terra (see above), with the dark brown plume of ash spreading in a narrow band to the west.

Ash from the eruption was noticeable as far as 15 km from the volcano and due to this new explosive event, CONRED raised the alert around Pacaya to Yellow (2 out of a scale of 4) and the plume was easily seen from Guatemala City, which is only about 50 km away from the volcano. The eruption also prompted some flight diversions due to the ash plume.

 

The eruption of Pacaya in Guatemala, seen on March 2, 2014. The lava fountain (reddish) can be seen at the summit vent. Image: CONRED.

The eruption of Pacaya in Guatemala, seen on March 2, 2014. The lava fountain (reddish) can be seen at the summit vent. Image: CONRED.

The unrest that started on Sunday is continuing, with more explosions, eruptions and earthquakes, so evacuations are underway for people living close to the volcano. The latest CONRED report mentions lava flows on the western part of the volcano that have travelled 1200-1300 meters downslope while explosive activity has waned some to only small explosions at the summit vent.

From the looks of the images and descriptions, this eruption is another energetic strombolian eruption typical for Pacaya. It is a volcano that behaves is ways very similar to Italy’s Etna, where basaltic lava eruptions as fire fountains or lava flows. This new eruption is part of a period of activity that began in March 2013, but this explosion was larger than what had been seen so far. However, the previous period of activity from 2004-10 did feature some eruptions as vigorous as the March 2 event.

As a sidenote, I did notice that CONRED includes this sentence at the bottom of their statement on the eruption: “The general population is advised to be alert to indications that authorities release through the media, avoid spreading rumors, avoid risking your life, take the directions of the authorities…”  (emphasis mine). I think this is an especially important message to get across in this age of social media.

from:    http://www.wired.com/wiredscience/2014/03/guatemalas-pacaya-enters-new-phase-eruptions/#more-565421

Costa Rican VOlcano Poas Eruption

Eruption Update for February 28, 2014: Poás,

The opening salvo of the eruption at Poas in Costa Rica, captured on the crater webcam. Image: OVSICORI webcam capture.

The opening salvo of the eruption at Poás in Costa Rica, captured on the crater webcam. Image: OVSICORI webcam capture.

Costa Rica

Earlier this week, Poás in Costa Rica had a small eruption likely related to water flashing to steam in the heating crater lake area. This eruption ended up being the largest so far in 2014, but these types of explosion are fairly common at the Costa Rican volcano. That being said, María Martínez Cruz (OVSICORI) said that the size of this eruption, with a plume that reached 300-meters, is not too common at Poás. This could suggest that more heat is being fed into the upper reaches of the volcano. The webcam at Poás captured the eruption as it occurred, spreading ash mainly within the crater area. If check out the webcam at night, you can see some intense incandesce that betrays the magma just beneath the surface at the volcano. Not surprisingly, the volcano is off-limits to tourists.

from:    http://www.wired.com/wiredscience/2014/02/eruption-update-february-28-2014/#more-561421

Indonesia – Kelud Volcano Erupts

Kelud Eruption Kills Three People, Forces 100,000 to Evacuate

The eruption at Kelud (Kelut) on February 14, 2014. Image: @hilmi_dzi / Twitter, used by permission.

The eruption at Kelud (Kelut) on February 14, 2014. Image: @hilmi_dzi / Twitter, used by permission.

The eruption at Kelud (Kelut) has rapidly become another humanitarian crisis for Indonesia. After the impressive explosive eruption yesterday, over 100,000 people have had to evacuate the region around the volcano in case further explosions occur. The heavy ash fall from the explosion has coated towns and cities (see below) over 100 km from the volcano and lead to injuries and deaths after a roof collapsed at one of the evacuation shelters. Currently, the death toll from the eruption is only 3 (2 from the roof collapse and 1 from ash inhalation), but that number may climb. At least three international airport were closed due to the ash and the plume itself (at least the sulfur dioxide) was still clearly visible in satellite images (see below). Some people leaving comments on yesterday’s post said they heard the blast of the eruption over 180 km from the volcano and ash was falling upwards of 200 km distant — to the tune of 5 cm! Be sure to check out the discussion of the shockwave from the blast over on the CIMSS Satellite Blog.

 

The sulfur dioxide plume from the Kelud eruption, seen at XXX UTC on February 14, 2014 via GOME-2. Image: XXX

The sulfur dioxide plume from the Kelud eruption, seen at 0637 UTC on February 14, 2014 via OMI. Image: OMI/NASA-NOAA

The PVMBG has said that they were surprised how quickly the volcano went from having shallow earthquakes to a full-on eruption. Normally, they expect at least 6 hours between the onset of earthquakes before an eruption at Kelud, but in the February 14 eruption, it was only ~2 hours. This meant that implementing the evacuation after raising the alert status was very difficult for Indonesian disaster relief agencies.

The ash from the February 14, 2014 eruption of Kelud in Yogyakarta. Image: Robert Schrader, used by permission.

The ash from the February 14, 2014 eruption of Kelud in Yogyakarta, ~200 km from the volcano. Image: Robert Schrader, used by permission.

Activity at Kelud tends to be punctuated — at least looking at past eruptions — where an explosive event occurs and then the volcano settles. However, it is unclear from any of the reports I’ve seen whether the PVMBG thinks that new eruptions are coming soon. Based on the evacuation that is occurring, my guess is that they think that the volcano will be restless for the foreseeable future. I haven’t seen any news about lahars generated by the eruption so far, but they are a major hazard with any activity at Kelud. Most volcanologists I’ve heard from about the February 14 eruption say it looks to be on scale with the 1990 eruption, which was a VEI 4.

from:    http://www.wired.com/wiredscience/2014/02/kelud-eruption-kills-3-people-forces-100000-evacuate/#more-543661

Erik Kelmetti’s Volcano Update

Eruption Update for January 13, 2014: Sinabung, Pacaya, Shiveluch and Etna

An a’a lava flow from Pacaya in Guatemala burning its way through a forest, seen on January 11, 2014. Image: CONRED.

Some volcano news to start off the week of January 13, 2014:

Indonesia

The eruption at Sinabung is continuing unabated and now evacuees have reached over 25,000. The repeated cycle of dome building and collapse are producing dozens of pyroclastic flows, mainly within 5-7 km of the summit of Sinabung. However, the significant ash fall that accompanies such eruptions has been enough to collapse roofs and destroy homes in villages near the volcano. Ash has also been falling as far as Medan (the capital of North Sumatra), which is ~60 km (35 miles) from Sinabung and Langkat, which is ~77 km (48 miles) away. The economic impact is being felt not only in the agricultural core of the region, but also in tourism.

Guatemala

Eruptions at Pacaya has also prompted CONRED to call for evacuations, but on a much smaller scale than at Sinabung. Lava flows stretching 3 km from the main summit of the volcano are the cause for this limited evacuation for people living closest to the volcano. Explosive activity has accompanied these lava flows as well — a very typical behavior for these Strombolian eruptions at Pacaya. Even as basaltic lava, these a’a lava flows (see above) do not move quickly, as these images of CONRED officials examining the flow can attest, so the real hazard is to structures that stand in the path of these extensive lava flows.

Russia

Shiveluch has started off 2014 with a bang as well. Ash plumes reaching 7-9 km (25,000-30,000 feet) along with pyroclastic flows have been occurring due to the same cycle of dome building and collapse that we’re seeing at Sinabung — a very standard behavior for arc volcanoes like these two. Thanks to its remote location, Shiveluch doesn’t pose much in the way of human hazard, but some villages on the Kamchatkan Peninsula have had some minor ash fall due to the eruptions. You might be able to check out the action on the Shiveluch webcam as well.

Italy

I meant to mention this last week, but Dr. Boris Behncke had a brief post on the rumbling at the Northeast Crater of Etna. Over the past year, much of the action has been at the New Southeast Crater, but that is a recent phenomenon. Although the Northeast Crater has taken a back seat lately, minus some ash emissions, apparently there is some speculation that this could change based on its current state of degassing.

from:    http://www.wired.com/wiredscience/2014/01/eruption-update-for-january-13-2014-sinabung-pacaya-and-etna/#more-499781