Hydrothermal Explosion Explanation Please

[JoshSHill]

G'day there peoples, I'm new, so bear with me...

 

I'm a journalist, and I'm writing a piece on the following story...

 

http://www.physorg.com/news119553781.html

 

I need to know just what it is that is causing the hydrothermal explosion. I headed to this site;

 

http://www.hanksville.org/daniel/geology/explosion.html

 

And I got the following, but I'm not certain;

 

A hydrothermal explosion is caused by the combination of superheated water turned to steam meeting with cooler water (or is it) with ...

 

Please explain, and soon... lol!

Josh

[swansont]

A mole of liquid water takes up a volume of about 18 cm^3 (that is, 18g at 1g/cm^3, which is the density of water)

 

A mole of an ideal gas takes up 22.4 L of volume. Basically, when flashing to steam, the water wants to expand by a factor of 1000 (water won't be an ideal gas, but the effect should still be the same order of magnitude). Under normal conditions, water boils at 100ºC and it takes ~40,000 Joules of energy for that small sample to become steam (2260 kJ/kg) That energy is already in the water when you superheat it, but the pressure is too great to boil. Once the pressure drops sufficiently, and the water is still hot enough, it can flash to steam and expand.