Potential Disaster in the Making 10

[phamENG]

Cumbre Vieja, a volcano on La Palma in the Canaries, just erupted a couple of hours ago. National Geographic did an episode on it as part of a 'Disaster Earth' series a few years ago. Essentially, there's evidence of a massive landslide on the island a few hundred millennia ago, the likes of which would have formed a tsunami large enough to hit the east coast of the US. A recent earthquake seems to have restarted the process and formed a large fissure along the island.

Here's to hoping it doesn't move any more....

 

[1503-44]

03 10 2021 18:56 UTC
Yesterday's flows over new territory were mostly into the SE quarter of El Paraiso. That area is only 1km away from the last vent to open up on the north side of the group.
Also looks like its setting up to take out some nice houses on the north side of the south cone in La Laguna. Hard to give them much of a chance.

The volume of lava emitted so far was reported yesterday at 80MM m3. Rughly 60 m3/s.

 

[itsmoked]

Is that ash the type that locks-up if left alone or is it more like sand?

Keith Cress
kcress -

http://www.flaminsystems.com

 

[RedSnake]

Now it is starting to get hot..

“Logic will get you from A to Z; imagination will get you everywhere.“
Albert Einstein

 

[1503-44]

Oh I think it's been hot all day. Now that near infrared is visible again.

I think the dust is somewhat "reactive" or maybe electrostatically charged. Or it's just the very fine particle size that makes it hard to clean. Sahara dust also has very fine sized particles.

Light rain today left some fine black streaks, so we are getting some of it.

17 3.x earthquakes today from Mazo to Fuentecaliente. 2 x 3.7

 

[FacEngrPE]

Regarding the discussion above
Scattered light of of the particulates likely is a large part of the difficulty of seeing the lava fountain. The daytime scattered sunlight is brighter than the black body radiation of the lava fountain, which is also scattered. This screen shot shows some of the scattering. - The illuminated smoke on the right side of the image that is mote likely to result in colored smoke than further obscuring the fountain.
I do not discount the effect of gas to act like a light filter, but I think

There are published estimates of the temperature of the Lava at the cliff side as being 1000 C. Has anyone seen a real number for lava temperature at the vent?? I do not trust comparing the black body color chart, as the camera is probably saturating in the bright (hottest) spots.

https://blog.inspiredled.com/wp-content/uploads/2017/09/Kelvin-Temp-Chart.png[/URL]]

 

[AusG]

Black body temperature is reasonably OK if you could see the thing live and/or use an optical pyrometer. The published melting temperatures of basalt magmas are around 1000 C - 1300 C and from my own experience with kilns this looks about right for the colours in the images.

 

[human909]

Talking a bit beyond my knowledge here but it would be entirely expected that the magma exiting to the surface is a fair bit above the melting temperature. If it was AT the melting temperature then the boundary layer would be increasing in viscosity and solidifying and you'd get reducing flow. To have maintained flow or increasing flow you are going to need to have the exiting magma at temperatures sufficiently above the melting point that it maintain fluidity for an extended length of time.

Explosively ejected particles would be expected to cool to the solidifying temperature fairly quickly hence the red outside with the yellow interior.

My 2cents. But feel free to tear apart my seat of my pants assessment.

 

[TugboatEng]

You're on the right page. Discontinuities can't exist in nature. With that said, the air in contact with the surface of the lava is at the same temperature as the lava. The inside of the lava flow must be much hotter than the outside in contact with air. Only at the vents, where the lava is moving with great velocity and in small chunks,is the surface temperature close to the core temp. Also, if there are any combustible materials such as iron, the surface may then appear hotter than the core as it's exposed to oxygen and burns.

 

[AusG]

You are right enough. Assuming the magma is (partly) melting its way up, and spent some time at various intermediate depths it will be near whatever equilibrium temperature fits the mix of crystals and liquid chemistry the last magma chamber contains. (draws elaborate phase diagram in the air). The last magma chamber will be hotter and deeper than the vent so yep, the stuff inside the throat will be significantly hotter than the melting of that exact mix. Not sure how much of that is visible though. Viscosity might also be more to do with contained volatiles than just pure temperature. It is a very dynamic system as volatiles come out, and some minerals crystalize out preferentially. I suggest we run up there with an optical pyrometer and some very thick clothes.

 

[dik]

and safety goggles?

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[1503-44]

I haven't seen any temperatures published since the first few days of the eruption, which was 1237°C. The lowest I'e heard mentioned 1050°C during thick lava flow events. Lately the lava flows have been fast and hot, so I assume it would be back in the 1150-1250 range again.

These will have to do ..

 

[1503-44]

Speaking of clouds,
"Mysterious waves that have appeared over the volcano"

This video shows the interaction of the eruption plume with the Sahara Air Layer temperature inversion capping the top. It makes the plume flow horizontally at 5300m msl. The volcanoes pulsations at different intensities causes these waves.

/Este video @cielodecanarias muestra la interacción del penacho eruptivo del #VolcanLaPalma con la inversión de Tª del tope de la "Saharan Air Layer" que le obliga a un desplazamiento horizontal a 5300m snm. El volcán emite pulsos de diferente intensidad lo que provoca esas ondas!/

https://diariodeavisos.elespanol.co...ue-han-aparecido-sobre-el-volcan-de-la-palma/

 

[1503-44]

Rocks up to 400mm have been tossed 800m. I estimate a 250-300m torch height. 820ft. 70m/s vent exit velocity 233 fps. Exit pressure of 1000+ psi, 70 Bars Hard to say for sure due to gas and possible two phase flow within the vents.

413 ha covered with lava, 14ha in the last 24h.
The lava has formed two pipelines. Since the solidified crusts of the tubes act as insulation, only losing 1°C/km traveled, they should keep lava from collecting upstream by maintaining low viscosity and high velocities within the pipeline.

1047 buildings destroyed and 4000 ha covered with ash. 30ha of new area has been added at the beach.

 

[FacEngrPE]

Gas exit pressure of 1000+ psi under a slug of molten rock would surely look like an explosion (or sometimes cannon shot), a larger slug of gas would explain the periodic shock waves. As gas must fizz out of the lava as it rises, two phase flow with slugs seems almost certain.

Some of the earlier images seemed to show gas and burping (rock and cinder ejection, and larger fountains) present more at the higher vent while the lower vent was calmer but with much more liquid flow. The underground plumbing may have been doing some phase separation.

 

[itsmoked]

only 1°C/km? Seems too good. I'd think more like 100°C/km.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[dik]

I would think that with the reduced pressure (weight of rock over) that the gas pockets would expand prior to popping...

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[dik]

@44... what is your source? Excellent information.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[1503-44]

The lava is reaching the ocean 6km away simply flowing in noninsulated surface channels, so heat loss cannot be -100C/km in a tube or even on the surface. At -100C/km it would all solidify before reaching the ocean 6km away.

☆ ☆ ☆ Volcanic Landforms and Hazards
Lava tubes are very efficient transporters of lava from the vent to the flow front, and calculations show that lava flowing in a tube cools by only about ....

 

[1503-44]

Some theories I've been reading lately propose both slug and annular flow, depending on type of volcano, determined by all of the following interdependent parameters, gas and water content (3 to 6% typical range) flow rate, temperature, 750-1250°C pressure, viscosity, 10k to 100k x water,and chemical composition of the lava.
"Low viscosity magmas, such as some basalts, can form very long lava flows very rapidly. In contrast, rhyolite magmas are viscous enough to limit bubble movement. Rather than escaping by buoyantly rising through the magma, gas bubbles are trapped in rhyolite magmas, expand, and eventually create very explosive eruptions."

It's the slug slow that is predominately responsible for the explosive characteristic. La Palma is rated as explosive Cat. 2 of 8 categories, where each Integer value is 10x the magnitude of the previous. Yellowstone caldera is an 8, so tread carefully there.

Sources are from Duck Duck Go search engines image feature. Sort through a bit of junk and there is some useful info there. I think the climate change deniers, antivaxers and flat earthers haven't figured out volcano antiscience yet.

 

[1503-44]

02 10 2021 12:02 UTC