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09-09-2015, 10:31 AM
Brian,
you are correct about pore pressure on faults. At first I thought pore pressure would be mixed up in the sliding on the table, but since there was an opposite effect, it was not pore pressure so not same as earthquakes.
Chris
[/quote]
I'm not sure it would be the same. On the table, you are comparing the friction between the two surfaces with and without the presence of the water. But underground, water is always present, is it not? I thought it had more to do with pore pressure; that is, the pressure of the water present in the spaces. I might have this backwards, but I thought that increased pore pressure pushed rock particles apart, reducing friction from asperities, tending toward fault failure.
Brian
[/quote]
you are correct about pore pressure on faults. At first I thought pore pressure would be mixed up in the sliding on the table, but since there was an opposite effect, it was not pore pressure so not same as earthquakes.
Chris
[/quote]
I'm not sure it would be the same. On the table, you are comparing the friction between the two surfaces with and without the presence of the water. But underground, water is always present, is it not? I thought it had more to do with pore pressure; that is, the pressure of the water present in the spaces. I might have this backwards, but I thought that increased pore pressure pushed rock particles apart, reducing friction from asperities, tending toward fault failure.
Brian
[/quote]