Can pyroclastic flows cross water? While reading the Wikipedia article on pyroclastic flows, I noticed that there's a section called 'Interaction with water'. This piqued my interest, as I was under the impression that lava generally doesn't interact much with water other than cooling down.

To my surprise, this claim is made in the article:


  Testimonial evidence from the 1883 eruption of Krakatoa, supported by experimental evidence, shows that pyroclastic flows can cross significant bodies of water. One flow reached the Sumatran coast as much as 48 km (30 mi) away.


I tried to look up the citations, but they're both in books that I don't have access to at the moment. Can these flows cross water, and how?
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 the main town was destroyed - which suggests the pyroclastic flows crossed the harbour.

Also my u/g mapping area in North Wales included the Snowdon Volcanic Group. It and related tuffs appear to have been erupted over water and/or wet estuary type environments (there is open to debate).