16

In answer to the title question, "yes"! Here are some videos from Montserrat Soufriere Hills where the phenomenon has been extensively studied (probably more than anywhere else): http://www.geo.mtu.edu/volcanoes/west.indies/soufriere/govt/images/051296/ As well as Krakatoa, Mt Pelee's (Martinique) 1902 eruption managed to ignite ships in the harbour when ...


12

Can't help with the details, but think about it like this. It is a density current (denser than air, that's why it flows downhill), but the density is less than that of water, so it will flow across it. Compare this to turbidity flows (also density currents), which are denser than water and will therefore flow downhill in the ocean.


9

Pyroclastic flows can cross water. This doesn't suggest that any pyroclastic deposit can cross water. High energy had needed. For high energy a caldera forming explosion and/or high temperature flow had needed. Crossing water also doesn't suggests every material in a single flow pass over the water. Gradually the flowing material amount decreases. The distal ...


9

I think I recall that being superheated, the pyroclastic flow can cross water as it can ride over a layer of steam generated from the water surface, sort of like a hovercraft, but riding on steam rather than blown air. Also Lava/volcanoes do interact with water, aside from the relatively benign interaction with basaltic pillow lavas (which I assume is the ...


5

Probably the best known is more recent, the 1902 eruption of Mt. Pelée on Martinique, where 30,000 people were killed by pyroclastic flows. I don't know the extent of burial - it appears that the city may have been destroyed more by the ash cloud than the dense part of the flow.


3

Here is another example: Ceren (El Salvador) around A.D. 660 (discovered in 1978). Ceren is believed to have been home to about 200 people. Researchers have excavated 12 buildings, including living quarters, storehouses, workshops, kitchens, religious buildings and a community sauna. There are dozens of unexcavated structures, and perhaps even another ...


2

Volcanic plumes and pyroclastic flows are two behaviours of basically the same thing. A volume of hot gasses and tephra (a.k.a. a mix of ash, pumice, and volcanic rocks of different sizes). If the gas is hot enough and the tephra content is light enough the mix will be buoyant and it will rise as a volcanic plume. On the other hand if gas is too cold to ...


1

The name of the cavities are lithophysae. They show that the current has high volatile content. Vapor phase devitrification is the origin of litophysae. Pyroclasts in the curremt maintain their volatile content till compaction. volatiles escapes from the clasts during deposition to the weakness zones of the flowage. After exsolution, the laminae (source of ...


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