Can you survive a lahar?

Factual Questions
1

On a TV program a while back about Krakatoa, they showed how a lahar (or pyroclastic flow) could travel across water. Lahars kill by scorching your lungs and then filling them with ash / cement.

If you were in a boat and had SCUBA gear, could you survive by diving into the water? (Somehow I think that diving and holding your breath wouldn’t work). What if you were on land and in a location protected from the heat blast? Say the store-room of a diving shop.

I’m aware of the prisoner on St Maarten (?) who survived by being in a deep prison cell, but that wasn’t a lahar, it was a gas discharge.

It seems to me that SCUBA gear would protect your lungs from the heat and the dust, but how quickly do lahars pass or subside?

2

I initially thought this thread was about operetta. I assume people can survive Léhar, but I can’t for the life of me see how.

3

You’re confusing two different things. A lahar is a volcanic mud flow produced when an eruption melts snow and ice near the peak of a volcanic mountain. The water rushes downhill gathering up mud, rocks and other debris.

A pyroclastic flow is a cloud of hot ash and superheated gases that results from certain types of explosive eruptions, such as Mt. St Helens or Pinatubo. These pretty much burn everything in their path, with internal temperatures as high as 1000 F.

4

It isn’t just your lungs that you have to worry about. A pyroclastic flow is going to be moving at high speed, carrying all sorts of debris. So you also have to deal with physical trauma and temperatures that can produce instant third-degree burns.

5

They identified them as the same on the program.

6

They were wrong.

7

Well yes, that’s why I specified diving underwater or being protected.

8

The water flash vaporizes. You’d be parboiled.

9

No. There’s not nearly enough energy available to totally vaporize a large body of water. A pyroclastic flow is essentially hot gas; its specific heat is low in comparison to water.

10

Well, no not the entire ocean. But certainly a few feet.

11

Puddles, maybe. Ponds and larger water bodies, no.

12

Deeper water should protect you, if you dive deep enough. A small pool could quickly get boiling hot. The eruption could heat the water by means not due to the super heated air mass and still boil you. It would be very similar to a fire storm. Read about the Peshtigo fire.Read about the Pestigo Fire of 1871. It’s an account that we have of people busting into flame from the super heated gases. Many people tried to survive in the streams and some in wells. The fire lept 30 acre cleared areas. This article claims the heat was over 2,000 F. The most likely cause was a meteor shower that started the logging debris on fire.

The moving mud is a fine powder, that turns into a fast moving slurry year after year. People down from the old mud flows have to worry about their lives after much rain, because the mud reconstitutes and starts moving as a slurry again.

Java has a big flowing mud problem from an oil drilling debacle, that you may like to read about. Here’s another good picture. Here’s a third picture with a a larger area shown. I see Java is the world’s most densly populated island. I see that this disaster has displaced over 10,000 people so far.They seem to have started dropping cement balls with chains into the opening. I have to wonder if it won’t have the opposite of the planed effect, and the mud will errode away a wider hole.

I see the volcano filmed in the lord of the Rings is ready to release a mud flow in the next month. Mount Ruapehu

13

Quartz
The event to which you referred was the eruption of Mt Pelee on the island of Martinique.
The prisoner who survived was Ludger Sylbaris

14

[nitpick]
Java is the world’s most populous island with over 120 million inhabitants, but it’s far from being the most densely populated, even though the claim has been made elsewhere.

Ap Lei Chau island, part of Hong Kong, has ~90,000 inhabitants in 1.32 square kilometers (i.e. more than 170,000 per square mile). By comparison, Manhattan has about 67,000 per square mile. Java, at about 2000 people per square mile, isn’t even close.
[/nitpick]

15

How to survive : http://www.youtube.com/watch?v=lW4s7TETtJA

16

a pyrochastic cloud is also poisonous. One occurred in Japan when I lived there in 2001.