"Tek" <tek### [at] evilsuperbraincom> wrote:
>
> Well according to any number of discovery channel documentaries it's pretty
> common. Volcano erupts, suddenly melts lots of snow, huge flooding in
> surrounding areas. The specific eruption that inspired this image was Mt.
> St. Helens, though the initial eruption was mostly just a huge explosion of
> snow and rock, and lava might not have started spouting out of it until all
> the snow was gone.

In 1985, the Colombian volcano Nevado del Ruiz washed the town of Armero off
the map with a catastrophic snowmelt.  A massive snowmelt is forecast to be
the method Mt. Rainier will use to waste Seatle-Tacoma.

I don't recall any lava in the Mt. St. Helens eruptions; only ash, steam,
and pyroclastics.  I think the magma just blew itself into ash after the
north flank collapsed and releaved the pressure.

>
> This isn't meant to be a stable eruption, so I'm going to need to work on
> some more dramatic effects I think.
>
> "Darren New" <dne### [at] sanrrcom> wrote in message
> news:43d66ec3$1@news.povray.org...
> > The ground is both too black and too bare. Lava is very shiney, as the
> > surfaces were all liquid a short time ago and cooled under gravity. It's
> > mostly brittle and crunchy, like blown glass. Plus it's full of delicious
> > plant nutrients, so even days after an eruption, you get grass there,
> > saplings, etc.
>
> In hawaii this is true, and that's the only volcano I've been to. but my
> understanding is that volcanos that have lain dormant for a while actually
> end up covered mostly in very fertile dark soil and more mountain-like rock,
> and less smooth glassy rock... maybe... you know it's really beginning to
> sound like I need to do some research for this image! how tedious!

As Alain pointed out, the Hawai'ian volcanoes are fundamentally different
from the Cascades volcanoes such as Mt. St. Helens and Mt. Hood.  Low
silica (fluid) lavas cool to dark basalts; high silica (viscous) lavas cool
to lighter-colored rocks.

But not only are the form and color of the mountains different, the
eruptions are majorly different, due to the consistencies of the lavas.
Fluid lavas tend to erupt into copious, but well-behaved lava flows.  They
look like the best Hollywood-style killer infernos, with large, turbulent
pools of glowing red molten rock, giant pink gas-propelled fountains, and
rivers of lava hurtling towards the sea, everything you'd expect from
Dante's _Inferno_.  Quite a sight!  Alas, these eruptions are paper tigers;
they are so nonlethal that in Hawai'i they give tours while the volcano is
active!

Contrast that with Mt. St. Helens.  There are two tourist roads leading to
the site, and neither of them so much as approaches the base of the
mountain.  When a high-silica volcano such as Mt. St. Helens stirs, they
talk how many dozens of miles away they'll need to evacuate on 48 hours
notice.  Then the eruption itself is ugly.  Mud, flash flooding,
pyroclastic flows, hot ash all over the place, a lot of gritty smoke (the
cauliflower-like Plinian column), and nighttime at noon for hundreds of
miles around.  Color?  A drab rgb <0.1, 0.1, 0.1> or so.  The picturesque
lava may not even show up!  The visuals aren't something to pull in the
movie goers, but in real life, these are the real killer eruptions.

The blast damage is pretty cool, though.

> Hmm... I thought I'd get away without radiosity in this image, but I think
> if I have much lava I'll need it...

With the smoke column you have, i'd think it would almost be mandatory.
Perhaps only at night though.  I've never seen an eruption up close,
although i've seen the volcano in Montserrat (Soufriere Hills) from a
distance, plus a lot of footage.  (Not sure i'd like to witness an ash flow
up close, in any case.) Soufriere Hills is a composite volcano, with ashy,
explosive-type eruptions.  From a distance, all i could see was varying
shades of gray: light gray, dark gray, cool gray, warm gray, all gray. :-P

pretty much as Pliny described it.  In daytime footage, i could see some
red glows on the underside the lateral ash flows; perhaps sunlight
overwhelms the glow, the same way that a daytime sky overwhelms the stars.

Post a reply to this message