Pyroclastic flow

Pyroclastic flows are the deadliest of all volcanic hazards[3] and are produced as a result of certain explosive eruptions; they normally touch the ground and hurtle downhill or spread laterally under gravity.

The lower density sometimes allows them to flow over higher topographic features or water such as ridges, hills, rivers, and seas.

[13] A 2006 BBC documentary film, Ten Things You Didn't Know About Volcanoes,[14] demonstrated tests by a research team at Kiel University, Germany, of pyroclastic flows moving over the water.

During some phases of the Soufriere Hills volcano on Montserrat, pyroclastic flows were filmed about 1 km (1⁄2 nmi) offshore.

[citation needed] In 1963, NASA astronomer Winifred Cameron proposed that the lunar equivalent of terrestrial pyroclastic flows may have formed sinuous rilles on the Moon.

In a lunar volcanic eruption, a pyroclastic cloud would follow local relief, resulting in an often sinuous track.