OT Moon causes earthquakes?

[harry]

[F Murtz]

Has anyone compared earthquake frequency with before and after we started underground atomic tests and geothermal heating and extraction of oil and other underground fiddling etc. etc.?

[harry]

Pretty insignificant compared with the moon I suppose. I read somewhere about injecting water into geological faults to try to relieve tectonic stresses progressively.

[Brian Gaff]

Hardly new news though. When they first found the moon IO, they explained it was heated internally by tidal forces, using experiments carried out on earth with our moon, where the land moved due to the tidal effect, just like the water does but the amount is much smaller but does cause heat and stress cracks to occur contributing to the likelyhood of earthquakes. Brian

[Chris Hogg]

AIUI in one of the mid-western states in the USA, many years ago they found that pumping water out of deep boreholes, for irrigation etc. caused earthquakes to be more severe. By reversing the process, injecting water rather than extracting it, they greatly decreased in intensity but were more frequent. The water in the rock strata acted as a lubricant, allowing gradual stress relief, rather than stress building up and the rocks then suddenly failing with a big shock. That's been known for ages.

As to the moon causing earthquakes, it might trigger them but the underlying cause is convection currents in the earth's mantle, causing chunks of the crust to move about (continental drift), bump into each other and get crushed at the points of contact, and it's the crushing and crumpling that causes stress build-up (and mountain ranges and volcanoes), and hence earthquakes. I can believe that when stresses in the rocks are high, additional stress caused by the moon, tips them over the top and they fracture, the last straw as it were.

[The Natural Philosopher]

Yes.

[Jethro_uk]

Indeed.

I am sure I have heard a few experts suggest that proximity to a sun is not a pre requisite for life, if the supporting body (planet, moon) can supply enough energy in other forms.

So it's not just planets that may support life we are looking for - it's moons as well.