6,000 Evacuated After Volcanic Lava Flow Spreads on Spanish Island

On Monday RockDoctor (Slashdot reader #15,477) wrote: Regular readers may remember recurring concerns over the instability of the island of La Palma, in the Canaries archipelago [population: 85,000]. Estimates of the threat ranged from 100 megadeaths (from tsunami impacts on the coasts of about a dozen countries bordering the Atlantic — including the eastern seaboard of America) down to a 10- to 30- metre tsunami with a few thousand deaths in the Canaries and other Atlantic islands (Madeira, Azores).

To bring relaxation and good cheer, today we have the news that the volcano at the centre of these concerns is erupting for the first time in 50 years. While a hundred or so houses have so far been destroyed and around 5000 people evacuated from the path of the lava flow, some people are more sanguine — Spain's Tourism Minister considers the eruption a "great attraction", and indeed recent eruptions in Hawaii did see a significant amount of "Volcano tourism". To be honest, I'm rather tempted myself — Etna studiously did not erupt during my last holiday there. Or should I wait for Vesuvius to go off again?
Here's an update. "Seven days after a volcano on La Palma erupted, lava flow and ash continue to spread shutting down the local airport and leaving hundreds without a home," according to one newspaper report (with several photos of the aftermath). "As of Friday, almost 6,000 people have evacuated.

"The government is working to locate emergency housing for the affected families as researchers are unsure when the ash and lava flow will stop."

Meanwhile, the Associated Press reports, "scientists said another volcanic vent opened up, exposing islanders to possible new dangers." The intensity of the eruption that began Sept. 19 has increased in recent days, prompting the evacuation of three additional villages on the island, part of Spain's Canary Islands archipelago in the Atlantic Ocean off northwest Africa...

Emergency crews pulled back from the volcano Friday as explosions sent molten rock and ash over a wide area...

Re:

[kot-begemot-uk]

Not funny.

You are talking about 40M dead in USA alone. There is no way to evacuate the East Coast in time if La Palma blows.In addition to that the survival rate will be single digits on the Canaries, Azores, Madeira, Cabo Verde, most minor islands in the Carribean, Portugese coast, South Coast of the UK and Ireland and coastal areas of Brazil.

I know that island like the back of my hand - we have been there 6-7 times for a few weeks each and have gone everywhere within the limitations of where you can go

Re:

[RockDoctor]

If the west flank of the volcano fails and collapses into the sea catastrophically (important qualifications emphasised) then significant parts of those islands, and the Atlantic coastlines are at risk. But previous recent experience (Lituya Bay [wikipedia.org], Krakatoa [wikipedia.org]) suggests that the impact will be strongly related to the angle of the coast to the wavefront. So, to use one of your examples, Funchal on the SSE coast of Madeira will have a worse day than Santana municipality on the N coast. So,

In addition to that the s

Re:

[RockDoctor]

Bloody Slashcode inability to handle accented characters.

Re:

[kot-begemot-uk]

Could it have been part of monitoring for the siting of the La Palma observatory? Maybe, but they broke ground on that one ... back in the 70s, wasn't it?

One of the stations was near the observatory - right off Roque do lost Muchachos. You could see it 99 when going to the actual Rock, it was right udner it on the right about 50m from it on a ledge above the caldera. It got moved (probably not to attract tourist attention a few 100 meters to the side from the tourist paths. You can see it on sat pictures. It is the only "telescope" in the "telescope" swarm that does not have a tarmac, but a dirt track to it. SAT equipment and radar ranging equipment is visib

Re:

[RockDoctor]

A seismic station does not need either satellite communications (a weekly telephone call, or swapping of a memory card is sufficient for the seismic data) or laser (or radar) ranging equipment. It certainly doesn't need it's own satellite dish when it is within a few hundred metres of a major observatory and it's communications. You do need to record the location when you're putting the station hardware in, but part of the point of choosing your location is that it's firmly connected to the bedrock. While i

Re:

[kot-begemot-uk]

That's ... a big claim. McMurdo sound - with Mt Erebus just across the bay from it? I doubt the USGS would leave Kamchatka uninstrume

It has a station here and there in many locations

1. These stations are seismo only.

2. These stations do not have radar/laser ranging equipment to measure actual tectonic shifts.

3. No other place in the world is honoured by more than one. La Palma IIRC has 2 or 3.

Re:

[RockDoctor]

2. These stations do not have radar/laser ranging equipment to measure actual tectonic shifts.

I've never heard of anyone doing that as part of a geological survey using radar or lasers - the precision and reproducibility has never been good enough. (Obviously, building surveyors measure the new lay of the land after landslides with such equipment, but that's a different subject.) It has only really become feasible since the development of satellite-location systems, both direct (off the satellite) and diff

100 megadeaths from 30m tsunami

[RightwingNutjob]

Tsunamis have long wavelengths, let's call it 500km. http://tsunami.org/tsunami-cha... [tsunami.org]

A swathe of water and 1000km wide (to kill a whole coastline) and 500km deep would be 500,000 sq km = 5e11 sq meter of water. For every meter of wave height across that column, that's 5e11 tons = 5e14 kg of water raised by 1 m at g = 10 m/s2 = 5e15 joules of energy.

At a 30 meter wave height that's 1.5e16 joules of energy per 1000km of coastline.

The circumference of a circle centered on La Palma and drawn out to the edge of

Re:100 megadeaths from 30m tsunami

[PeterM from Berkeley]

You missed a key point, it's not just the energy of the eruption, it's the massive stored potential energy of a giant slab of mountain that suddenly slides into the sea, and gets converted MUCH more efficiently into tsunami than just a straight-up volcanic eruption. It's the big landslide, not any particular single eruption that creates the megatsunami.

Here's a PDF describing this threat in more detail.
https://websites.pmc.ucsc.edu/... [ucsc.edu]

Re:

[bardrt]

and another key point, which is "Does the world really need 99 more Dave Mustaines?"

Re:

[RockDoctor]

it's the massive stored potential energy of a giant slab of mountain that suddenly slides into the sea,

My emphasis added.

There is a lot of debate over whether the dozens (literally) of sector collapse deposits in the Canaries (alone - there are as many around, say, Hawai'i) happened as catastrophic landslips, or day-long landslides. We know that catastrophic landslides can and do happen ; we're a lot less sure over how often slow landslides happen; we're very sure that ultra-slow landslides happen, we just

Re:

[crunchygranola]

I thought nappes were rather like the opposite of a landslide - they are displaced by a thrust fault underneath thus being pushed forward and up(ish).

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[RockDoctor]

That is the impression you get from school-grade text books. But when you've got a fault with a 30 or 50 km displacement (not length of rupture) it can't have much of a vertical component to it without exposing some very esoteric rocks from the lower crust and upper mantle. That does happen, but (for examples from my own "back yard") I can only think of two examples west of the Urals, totalling a couple of dozen square km, while the nappes of the Scottish Highlands alone cover several tens of thousands of s

Re:

[XXongo]

Tsunamis have long wavelengths, let's call it 500km. http://tsunami.org/tsunami-cha... [tsunami.org]

A swathe of water and 1000km wide (to kill a whole coastline) and 500km deep would be 500,000 sq km = 5e11 sq meter of water.

I have no idea what you are calculating here. 500 km deep? The average depth of the Atlantic Ocean is 3.6 km.

Re: 100 megadeaths from 30m tsunami

[RightwingNutjob]

500km "long" perpendicular to the coast.

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[RockDoctor]

I have no idea what you are calculating here. 500 km deep?

The technical term "wavelength" was used, correctly. That is the inflexion-point to inflexion-point distance measured in the direction of travel of the wave.

Given the deep-ocean travel speed of tsunami of around O(500 km/h, "airliner speed"), and the oft-reported O(20 min) period of tsunamis hitting a coast, then you're implying a wavelength of O(130 km).

Re:100 megadeaths from 30m tsunami

[EvilSS]

100 megadeaths from 30m tsunami

What's that in Iron Maidens?

Re:

[RockDoctor]

Damned if I know. Should I wait until they're all suffering from Alzheimers before listening to their work?

Re:

[hankwang]

A tsunami is not a 30 m x 500 km x 1000 km plateau of water.

Tsunamis are formed when a barely noticeable wave of 500 km long and e.g. 10 cm high in deep sea reaches shallow water, where the wave velocity is much smaller. The 500 km becomes much shorter and the height increases proportionally.

Not very different from how breaker waves e formed at the beach.

Re:

[RockDoctor]

How much it matters is probably dependent on how much far down the gun barrel you can see. For you, maybe not important ; for someone in Florida or Suriname, maybe more important. Me ... I'm not in this firing line, but about 3m down in the subsoil (below the building's foundations, built on factory debris, but recorded in the architect's records from building the factory) is a sand sheet from the circa 8,200 BP Storegga slide [wikipedia.org] event.

Tourism

[techno-vampire]

Of course there's going to be a great boom in tourism. As long as there's been commercial air travel between the US and Hawaii there've been people who'd visit the islands to get a good look at an erupting volcano. Why should this be any different?

So is that tourism for

[Goatbot]

Watching the lava or watching the people run from the lava. I'll wait for the drone footage. Nature is a beautiful until she isn't and bad stuff like this happens, my thoughts are with those dealing with the loss.

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[PPH]

I wanted a better look at that house that the lava skirted around.

Re:

[antdude]

https://www.youtube.com/watch?... [youtube.com]
https://www.youtube.com/watch?... [youtube.com]

Well, there goes ...

[PPH]

... any hope of Spain meeting it's Paris accord goals.

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[thegarbz]

Implying that any western country had a hope in heck in the first place? Last I remember the Paris accord required action and not sitting around collectively with a thumb up your arse, which is basically status quo for ... well every country.

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[RockDoctor]

Do the Paris accord cover natural CO2 emissions or artificial ones? I thought it was artificial ones.

Re:

[RockDoctor]

Human made CO2 emissions - such as by penis-substitute vehicles - are several times greater than natural emissions. Stop waving your penis-substitute at people in broad daylight - and for that matter, decorating it with lights and driving it in the open at night.

Insensitive

[VeryFluffyBunny]

Describing the catastrophe that thousands of people, who are losing their homes, livelihoods & anything they can't fit into a vehicle within 1 hour, as "a great attraction" sounds pretty insensitive to me. One politician in mainland Spain described it as spectacular & was admonished for it by every media outlet & many politicians for the rest of the day. Try watching the Canary Islands TV news, even if you don't understand Spanish, to see how those people are trying to cope with the realisation that their lives as they know it have just ended.

Re:

[LostMyAccount]

Nothing makes a disaster easier to deal with than rich people jetting in and telling you everything's going to be OK, and then jetting back to a life of luxury. God bless them.

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[VeryFluffyBunny]

Except in this case, they represent the Spanish crown & government & are leading by publicly announcing & committing to supporting the victims, providing temporary accommodation in hotels, food & emergency supplies. That means that whatever funds & resources are necessary will most likely be allocated. The king's popular & it'd be a really bad idea to make him look bad by not following through on his promises.

Re:

[RockDoctor]

the realisation that their lives as they know it have just ended.

The previous eruption on this island was in 1971. Anyone who didn't know their homes were at threat was being wilfully ignorant. I doubt that ignorance would have extended to their insurance companies - if (and it's a big "if") they could have got insurance against volcanic damage. Insurance works against random low probability events, not against certainties - which is why having a car crash (even a minor one) changes the insurance company's

Re:

[VeryFluffyBunny]

Great! Why don't you go over there & explain all that to the victims? I'm sure they'd appreciate it.

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[RockDoctor]

When I (and a 30-strong class of others) visited two-islands-over for a week of vulcanology course (with a lot of hill walking in beautiful scenery) it was a topic of conversation in the bar of an evening, including the bar staff. Their take on it was "you're here, we're employed, we'll take the risk". That is a somewhat less crowded island though.

Re:

[crunchygranola]

Consider the island of Hawaii where there are housing developments built on lava flows from that long ago era of 1950 only to be destroyed in 2018. About one third of the land in Leilani Estates, 700 homes, were destroyed. No doubt to be rebuilt soon.

They are a great attraction

[DrXym]

Timanfaya park in Lanzarote is amazing for anyone who visits that island. The cones, lava tubes and barren landscape are almost otherworldly. Not sure I'd be happy to see my house eaten by lava flow, or become a tourist attraction but then again I think I would have the sense not to build a house under an active volcano in the first place.

Re:

[RockDoctor]

Timanfaya park in Lanzarote

There's a lava cave tourist site on Tenerife too - Cueva de las Ventana (Cave of the Winds), if I remember the name correctly, on the north coast, but I forget the address. Not too hard to find.

I think I would have the sense not to build a house under an active volcano in the first place.

I think that pretty much addresses the whole of the Canary Islands. Ditto Hawai'i.

You can shift your odds significantly by choosing different places on the volcano (the entire island group is ent

5 days from submission to posting

[RockDoctor]

Well, at least EditorDavid does acknowledge that I wrote and posted this on Monday, when the news was fresh, even if it did wait in the "piling system" for nearly a week.

Yes, the eruption has changed, weakened and re-intensified, changed output (lava-rich, ash-rich (closing and re-opening the airport) since then. As expected.

The only significant few cents worth I've got to add is that the historical record of eruptions on this part of the island is that they tend to last 50-100 days, so it's unlikely to stop tomorrow. Then ... probably a half-century of quiet before the next eruption.