On Thu, 6 Nov 2003 17:27:04 -0000, Pete Smith
wrote:

In article ,
says...

"Steve Firth" wrote in message
...
iantheengineer wrote:

Not everything works on the same principles are you so stupid??? Water
flows
under gravity does that mean rock will too???

Well yes it does actually.

Avalanche.
Landslip.
Continental drift
Lava flow



An avalanche ( arent these made of snow which formed water!!!) made of rock
, I think you are talking of a pyroclastic cloud. Go on then Steve upto what
level and in what areas are you educated too???




You're thinking of a pyroclastic _flow_, which is hot rocks & dust from a
volcano, behaving in _exactly_ the same way as water.

Can't see any references which say it behaves _exactly_ like water.
it's very unlikely in fact.


One of these is what "destroyed" Pompeii.

BTW, isn't rocks rolling down a hillside, behaving like water called a
"Rockslide"?

Never heard of a rockslide. Landslide, yes.


(I'd personally have used the term Avalanche too - I've seen
it used in relationship to rocks before).


In Physical Electronics a phenomena known as avalanche multiplication
occurs when a particle accelerated in an electric field can travel
long enough to aquire sufficient energy to liberate one or more
additional particles which themselves are accelerated by the field and
go on to create more collisions USW, USW. A lot of "Zener" diodes are
in fact avalanche diodes.Similar phenomena occur in Geiger counting
tubes, although in that case the "gain" is so high that every single
atom of the gas in the tube becomes ionised, (avalanche multiplication
mode) using a lower electric field it is possible to operate the tube
in a linear (so-called proportional) mode and output is proportional
to the energy of the original ionising event, but the "gain" is much
lower.

I personally regard any self-perpetuating chain of events in an energy
field as an avalanche. A rockslide, landslide or snowfall may/may not
be an avalanche.

By my definition Pyroclastic flows are not avalanches.

WRT Pompei (I've been there, by car :-) ). AIUI during the eruption
many, many kilotons of material were ejected 20+ Km into the
stratosphere and was being kept aloft by the momentum of the gases
and solids contiguously being ejected, eventually the force of the
eruption waned this process could not continueand this material
started falling to earth. This led many of the population of Pompei to
look at the eruption as it was happening and think they were safe.

:-(

DG