Re: 4.0 quake in Utah and mine collapse


"Belba Grubb" <trungsisterfan@xxxxxxxxx> wrote in message
news:1188955662.045081.117710@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
On Aug 22, 12:38 pm, t...@xxxxxxxxxxxxx (Thomas A. Russ) wrote:

Well, other than what was in your article, I don't really know anything
about maountain bumps, but I would expect that the pressure is from the
tons of rock above the mine (overburden?) pressing down on the walls
and columns of the mine. Since the shafts and passageways are empty,
the pressure of the air is much lower than the rock pressure, and when
the rock structure fails, you would get a collapse.

I have yet to read any of those papers at the Google Scholar link, but
there seems to be more force behind it than would be expected in an
ordinary collapse. It is said in the general descriptions that a bump
blows coal out of a seam. The injured and dead rescuers were buried,
they say, under 5 feet of coal. And it happens quickly, too. Also,
there were reports of blast-like (my word for it; I don't remember the
actual words used in the news story) effects at the site of the
original tragedy that nobody could figure out a reason for at that
point. Bumps are apparently very rare, which would suggest unusual
conditions that cause them: ? methane or some other gas, although
heat doesn't seem to be mentioned anywhere so they probably aren't
true explosions. It probably is some effect of the rock weight and
air and/or other gas under pressure from that weight; since they
happen in mines, that too could be a contributor. If they always blow
coal out of the seams, then the gas might be coming from that. Very
interesting.


I hadn't previously read anything about the miners being buried under 5-feet
of coal. How do they know? Isn't that just speculation? Perhaps the height
of the typical crawl-spaces they would be working in?

Also, I can't see how the"air and/or other gas" at the level of the mine
would be under any significant pressure. Even if the mine was below
sea-level, it would only be under slightly more than 14.7 psi of pressure.

But I agree, it's interesting.

Mike Williams
Arroyo Grande, CA USA


Of course, we're going to hear a lot about them at the congressional
hearings, but it's unclear, to paraphrase Ambrose Bierce, whether
those will shed more heat or light on the subject. Will have to look
at those articles some day when there is time.

Barb
----------
Water its living strength first shows, When obstacles its course
oppose.
-- Goethe

The formula for water is H2O. Is the formula for an ice cube H2O
squared?
-- Lily Tomlin



.

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