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Gravitational pull 'has role in quakes'

bbc.com

11–20 of 27 posts

Re: Gravitational pull 'has role in quakes'

#11
post #10

Earlier quoted context omitted.

Roughly half of all earthquakes are within one week of a full moon.

I dont believe the phase of the moon as anything to do with the earthquakes, more the orbital position...

Psst. The moon takes about four weeks to go from full moon to full moon, so "within a week of full moon" is roughly 50% of all days - earthquakes or otherwise.

Re: Gravitational pull 'has role in quakes'

#12
post #10

Earlier quoted context omitted.

I dont believe the phase of the moon as anything to do with the earthquakes, more the orbital position...

Psst. The moon takes about four weeks to go from full moon to full moon, so "within a week of full moon" is roughly 50% of all days - earthquakes or otherwise.

But the actual phase has nothing to do with it, the moons position around the earth does. It's possible to have a full moon over head or a new moon over head, the gravitational pull will be the same regardless of the phase. It's purely coincidental about it being a full moon.

Re: Gravitational pull 'has role in quakes'

#14
post #12

Earlier quoted context omitted.

Psst. The moon takes about four weeks to go from full moon to full moon, so "within a week of full moon" is roughly 50% of all days - earthquakes or otherwise.

But the actual phase has nothing to do with it, the moons position around the earth does. It's possible to have a full moon over head or a new moon over head, the gravitational pull will be the same regardless of the phase. It's purely coincidental about it being a full moon.

The phase is important because tidal forces are the sum of forces from both the Sun and the Moon. When the Moon is full, that is because the Moon is directly opposite the Sun. When the Moon is new, that is because it is directly in front of the Sun.

This causes minimums and maximums in the tidal forces on the Earth.

Re: Gravitational pull 'has role in quakes'

#15
post #10

Earlier quoted context omitted.

I dont believe the phase of the moon as anything to do with the earthquakes, more the orbital position...

Psst. The moon takes about four weeks to go from full moon to full moon, so "within a week of full moon" is roughly 50% of all days - earthquakes or otherwise.

I'm pretty sure OP was joking. Except what if the quakes are not evenly distributed? Then the joke is wrong :-)

Re: Gravitational pull 'has role in quakes'

#16
post #12

Earlier quoted context omitted.

But the actual phase has nothing to do with it, the moons position around the earth does. It's possible to have a full moon over head or a new moon over head, the gravitational pull will be the same regardless of the phase. It's purely coincidental about it being a full moon.

The phase is important because tidal forces are the sum of forces from both the Sun and the Moon. When the Moon is full, that is because the Moon is directly opposite the Sun. When the Moon is new, that is because it is directly in front of the Sun. This causes minimums and maximums in the tidal forces on the Earth.

Good point.

Re: Gravitational pull 'has role in quakes'

#18

Without gravity, there would not be very many earthquakes.

Or planets lol.

Plus no stars and any large scale formation, totally diffuse dark matter, and only the heavy elements from very early nucleosynthesis, assuming you could have a BB without gravity. Practically though, it's hard to imagine spacetime that has no curvature at all beyond a local IF.

Re: Gravitational pull 'has role in quakes'

#19
Tidal forces cause a lot of stress on celestial bodies.

The Moon is tidally locked to Earth. Its rotational energy was spent by rotating it while being tidally pulled.

A good analogy is: get a rubber ball, squeeze it on a flat surface and roll it (while squeezing it). That's what happened to the Moon.

Re: Gravitational pull 'has role in quakes'

#20

Earlier quoted context omitted.

Psst. The moon takes about four weeks to go from full moon to full moon, so "within a week of full moon" is roughly 50% of all days - earthquakes or otherwise.

I'm pretty sure OP was joking. Except what if the quakes are not evenly distributed? Then the joke is wrong :-)

It is a joke - but intuitively you'd expect some correlation between tides and earthquakes. It would be somewhat surprising if such correlation did not exist, and then I'd wonder what does that mean for the mechanisms that produce EQs.
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