Monday Musings: Soufriere Hills and Mayon (UPDATED) prompt evacuations

It's the last week of classes and it's also AGU (which I will be missing for the first time in 5 years). If you happen to be at the big meeting in SF and hear something you think we'd like to hear, feel free to drop me a line or leave a comment so we can live vicariously through you.

Pyroclastic flows at Sourfriere Hills, December 2009. Image courtesy of MVO.

Some news:

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Sally Sennert from the Smithsonian Institution sent me an email to say that this week's USGS/Smithsonian Institute Weekly Volcanic Report will be delayed due to the inclement weather in the Washington DC area. She can't connect with the server, so the report can't be updated on the Smithsonian…
Two impressive eruptions going on right now: Soufriere Hills erupting on February 11, 2010. Image courtesy of the Montserrat Volcano Observatory. Soufriere Hills just keeps on raising the bar during its new eruptive period. The volcano on Montserrat in the West Indies produced a 15 km / ~45 000…
Monday is here again already ... A pyroclastic flow from Soufriere Hills heading towards the ocean. Note the large volcaniclastic debris fan being formed by repeated flows. Dated March 2006. The "Science Advisory Committee" at Montserrat in the West Indies suggests that the current eruption of…
Image courtesy of Calvin Hall. Taken 3/28/2009 during an eruption at 10:59 AM3:28 PM. UPDATE 4/2/2009 at 11 AM Pacific: I'm moving this up from the comments, but Eruptions reader Doug Cole pointed out (and I have no idea how I missed this) that Redoubt has a new webcam! This one is at the DFR…

There is a video of the new Mayon eruption on YouTube, it's from the Philippine television station ABS-CBN and in the local language but the images clearly show a glowing, active lava dome at Mayon's summit and lava extending downslope from it onto the southeast flank, taking the same path as the lavas of the previous eruptions since 1993.

Thanks for that link, Boris. I'm going to bump it up to the article.

... and if Mayon weren't enough, also Piton de la Fournaise on the French Indian Ocean island Réunion has started a new and, as it looks, quite nice eruption, little more than one month after its extremely brief 5 November eruption.
The Institut de Physique du Globe has news (in French) and a really wonderful time-lapse video recorded by one of the webcams of the Piton de la Fournaise volcanological observatory:

Just my 2 cents about Mayon....

I really don't understand this volcano. How is it able to produce a viscous lava dome and fluid, fast flowing lava at the same time?

Is that thing erupting two different types of lava at the same time? (and is this even possible?)

Or is the dome an old feature built during an earlier andesitic eruption, and basaltic lava found its way through it?

Usually, basaltic volcanoes don't grow lava domes (I've never seen anything like that at Stromboli or Etna), and andesitic lavas are just too thick to flow like on the videos...

By Volcanophile (not verified) on 14 Dec 2009 #permalink

Volcanophile, I totally agree... the contrast between the two videos (Mayon and Reunion) is amazing.. ok, Mayon is a lot steeper but still. How does this work?

By bruce stout (not verified) on 14 Dec 2009 #permalink

I think it depends on the rate at which lava is emitted, whether it will build a dome or make a flow. Mayon is certainly not basaltic, maybe basaltic andesite. And andesite can absolutely flow - there are spectacular 15th to 17th century andesite lava flows at Mount St. Helens, Arenal in Costa Rica produces continuously andesitic flows, and even rhyolite can flow, the Rocche Rosse andesite (obsidian, actually) lava flow of Lipari (Aeolian Islands, Italy) being the example closest to my home.

Thanks a lot for the answers...

I looked up a bit on the GVP website about Mayon.. Boris, you're definitely right, it's basaltic andesite to andesite.

This volcano looks like a sort of transition between explosive and effusive type... it's capable of producing lava flows, but also pyroclastic flows and plinian activity...

Maybe the type of effusion also depends of the temperature at which lava is erupted... Hotter, more fluid lava found its way through the dome and is now flowing down the flanks...

Does the current behavior give any clues about what the volcano is about to do? Is it about to go strombolian and produce spectacular but quite harmless activity? or can it go back to kaboom-mode and go plinian (or worse still, pelean?)

Wait and see..

By Volcanophile (not verified) on 14 Dec 2009 #permalink

so what are the parameters for a flow then because the contrast between these two volcanoes is startling (all the more so when you consider the Reunion video is a time lapse).

At a guess I imagine it is a combination of flow, extrusion rate, temperature and slope/local topography. If you have a large enough body of lava it will not cool down so fast. Slope obviously also plays a large role. You can see how spread out and thin the flow on Reunion is, facilitating cooling and final stalling of the flow. Mayon on the other hand funnels its entire output into a narrow flow, conserving its heat (and therefore keeping its viscosity low) with the slope/gravity carrying it a long way down the mountain.. are any of these thoughts on the right track?

re the future behavior: lava extrusion suggests low gas content.. i.e. the eruption will not ramp up to Plinian.. is that a fair guess?

By bruce stout (not verified) on 14 Dec 2009 #permalink

Volcanophile: Mayon might well go into, err, 'kaboom mode', since several eruptive episodes have started with lava flows, progressing through strombolian to a final sub-Plinian spasm.
Maybe a bit like the 19th-20th Cent. Vesuvius eruptions- volatile-poor lava pours out, reducing pressure on gassy stuff lower down the conduit

At least one previous lava 'dome' at Mayon seems to have been the old crater floor pushed upwrads by rising magma beneath it, the new magma then flowing out as a lava stream from underneath the "carapace" of older rock..perhaps this one is similar?

Thanks a lot.. Mayon is indeed a fascinating volcano..

Usually, when a volcano erupts, the most violent phases are in the beginning. If we look at something like Mount Saint Helens or Chaitén, the most explosive "gassy stuff" was erupted first, then the activity stabilized into dome growth. Other, weaker eruptions like those from Hekla in Iceland, seem to show the same pattern, explosions first, then flowing lava.

Mayon, in fact, seems to do exactly the opposite. Gas-poor lava is erupted first (remnants from previous eruption?) then gas contents increases and the eruptions ramp up progressively.

Maybe this has to do with the plumbing system inside the volcano, perhaps an intermediate magma-chamber containing gas-poor material remaining from the last eruption. As this chamber fills up with hotter, gassier magma coming from the main chamber, the gas poor lava is first to be squeezed out, then gas-rich material reaches the surface and the eruption goes explosive. When the eruption is over, the contents of the middle chamber slowly degasses, ready for the cycle to be repeated.

In the other type of eruptions, material from the main chamber may be piped straight to the surface, explodes then loses pressure, ending the eruption by quiet lava flows.

All of this comes from pure speculation... I wish we had a way to see it going in real-time...

By Volcanophile (not verified) on 14 Dec 2009 #permalink

i got some big big news for Mayon

Mayon volcano in Philippines oozes lava; alert up

Authorities moved thousands of villagers from harm's way near the Philippines' most active volcano Tuesday after it oozed lava and shot plumes of ash, and said they probably will spend a bleak Christmas in an evacuation center.

State volcanologists raised the alert level on the cone-shaped, 8,070-foot (2,460-meter) Mayon volcano overnight to two steps below eruption after ash explosions and dark orange lava fragments glowing in the dark trickled down the mountain slope.

Nearly 50,000 people live in a five-mile (eight-kilometer) radius around the mountain, and authorities began moving thousands of them in case it erupts, Albay provincial Gov. Joey Salceda said.

The first of 20 vehicles, including army trucks, were sent to villages to take residents to schools and other temporary housing, provincial emergency management official Jukes Nunez said.

"It's 10 days before Christmas. Most likely people will be in evacuation centers, and if Mayon's activity won't ease down we will not allow them to return to their homes," Nunez said."It's difficult and sad, especially for children."

Magma had been rising at the volcano over the past two weeks and began to ooze out of its crater Monday night, but it could get worse in coming days, said Renato Solidum, head of the Philippine Institute of Volcanology and Seismology.

"Now lava is trickling down, but if the ascent of magma is sustained there will be laval flows," Solidum told The Associated Press."There is also the possibility of an explosion."

Residents in the central province of Albay are used to moving away from Mayon, which spewed ash last month and prompted the evacuation of some villages.

About 30,000 people were moved when it last erupted in 2006. Typhoon-triggered mudslides near the mountain later that year buried entire villages, killing more than 1,000 people.

Mayon's most violent eruption, in 1814, killed more than 1,200 people and buried a town in mud. A 1993 eruption killed 79 people.

The Philippines lies along the Pacific"Ring of Fire," where volcanic activity and earthquakes are common. About 22 out of 37 volcanos in the archipelago are activ

from here…

to Volcanophile: volcanoes do behave in very different manners indeed, and often the same volcano erupts differently each time. Mayon, which is very active and thus provides a record of numerous eruptions, is a very instructive example. In 1984, activity built up slowly - it started much the same way it's doing now - and then had its most intense phase after some two weeks. In 1993, it started with a devastating explosion and pyroclastic flow, leading to the nearly 80 deaths mentioned in David's note (11). Eruptions in 2000 and 2001 built up rapidly to strong explosive phases, whereas the latest eruption in 2006 remained relatively mild throughout (although more than 1000 people were killed in typhoon-generated lahars soon after the eruption).
A correction is due for Mount St. Helens in 1980 - it did not go full scale explosive at the start, but after six weeks of relatively small phreatic explosions, seismic activity, and very pronounced swelling of its north flank. Indeed, Chaitén is one of the few examples of a major explosive eruption that went paroxysmal right from the start. Soufrière Hills on Montserrat, on the contrary, took about two years to reach its highest levels of activity (from July 1995 to June 1997). It's all a question of how much gas is in the magma, and in particular, how much water vapor and carbon dioxide: these are the gases that drive volcano explosive. Lack of such gas was also the reason why the latest eruption of Mount St. Helens (2004-2008) was largely non-explosive.
In the case of Mayon, I believe that there we see something that we have often observed also at Etna: the conduit being essentially open all the time, each new uprise of more gas-rich magma first pushes out gas-poor magma remaining in the conduit, and that is why the onset of many Mayon eruptions is so gradual.

For those of you looking for photos and video footage of the new Mayon eruption, there's a lot of material coming up, and much of this is quite spectacular.
(from the latest images posted here you can see that lava effusion is increasing, with a significant lobe descending)…
I like in particular this one: