[Geysers] Lone Star Study

[Carlton Cross]

This article perpetuates a major fallacy about geysers.  Eruptions 
are not caused by a buildup of pressure; they're caused by increasing 
temperature and the formation of steam bubbles that reduce the pressure.

There are two major concepts that explain geyser eruptions:  1) The 
static pressure is determined by the depth below the water surface, 
and 2) The boiling point increases as the pressure increases.  Most 
of us have dived into a swimming pool and felt the pressure of the 
water as we go deeper.  We also know that a pressure cooker will cook 
faster because the water is hotter when it boils under pressure.

So, in quiet water, the pressure will be the static pressure 
determined by the depth, and, once the geyser reaches overflow, that 
pressure will remain constant at all depths.  Now, consider a column 
of water.  The deeper water can be hotter without boiling because the 
pressure at depth is higher.  As a glob of water rises because of the 
overflow of the geyser, the pressure on that glob will 
decrease.  Once the water column has heated sufficiently, the water 
reaching a particular depth will be hotter than the boiling point for 
that depth.  When it boils and forms steam bubbles, the bubbles will 
expand and rise which then reduces the pressure caused by the weight 
of the overlying water.  The pressure drop allows more water to boil 
and the process becomes self-sustaining.

Constrictions are often involved in geyser plumbing.  What happens in 
a constriction is that the pressure drops as the fluid moves 
faster.  Think about a hose that has a leak.  The faster the water 
flows through the hose, the less the water will squirt out of the 
leak.  In a constriction, the smaller the passage is, the faster the 
water will flow and the lower the pressure will be.  Again, once the 
steam bubbles start to form, the weight of the overlying water will 
decrease and the pressure will drop.  Thus, at a constriction, there 
are two reasons why boiling will occur.  It's likely that most 
geysers have significant constrictions, but a constriction is not 
necessary for an eruption to occur.

Carlton Cross


At 01:45 PM 7/21/2013, you wrote:
>Here is short synopsis of a longer article about a study done 
>recently at Lone Star Geyser. It quotes the longer study: The 
>Journal of Geophysical Research: Solid Earth, June 19 edition.
>
>http://www.livescience.com/38299-yellowstone-lone-star-geyser.html
>
>Pat Snyder
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