Of the four fundamental forces - gravity, electromagnetism, the weak nuclear force, the strong nuclear force - gravity is by far the weakest of them all.

If gravity is given a force value of 1, then the weak force is 10^25 times stronger, electromagnetism is 10^36 times stronger, and the strong nuclear force is 10^38 times stronger.

The two nuclear forces have extremely short ranges, only working within the nucleus of the atom itself, and are therefore completely irrelevant in the macro world outside of the atom.

Gravity works between masses, so if you get enough of it lumped together, it can add up. The only reason gravity appears so dominant in our every day experiences is due to the mass of the Earth. Black holes are examples of mass densities so extreme that gravity can overcome electromagnetism - gravity so strong that even light cannot escape.

Magnetism is but one aspect of electromagnetism (EM). EM waves are things like radio waves and visible light. They are oscillations of electric and magnetic fields traveling through space. The frequency of the oscillation determines in large part its properties. Low frequencies, say 640 kilohertz, would sit in the AM radio band (640 is KFI in LA). Ramp up the frequency to about 5.635^14 hertz and you have the frequency of green light that comes out of a green laser pointer.

Divide the speed of light by the frequency and you get wavelength. At frequencies like visible light, we use the wavelength instead of the frequency. The wavelength of a green laser pointer is 532 nanometers. The wavelength of KFI 640's carrier is about 468 meters.

Magnetism could loosely be said to be EM waves at zero frequency.

But I digress. The main point is that magnetism as a force is much stronger than gravity.

Although magnetism may be many times stronger than gravity as a force, due to the relative mass of the Earth gravity is the dominant force we experience. The dynamo in the Earth's interior that produces our magnetic field just isn't that strong. Man can make magnets much stronger. Heck, a simple bar magnet you can hold in your hand is strong enough to overcome gravity. That is demonstrated any time you pick up an object with a magnet. The magnetic fields in an MRI machine are 100,000 times stronger than the Earth's magnetic field.

So what about quakes? Can the use of MRI machines be correlated to the occurrence of earthquakes? Can gravity fluctuations be correlated to the occurrence of earthquakes? I think gravity would win this one hands down, simply because it's easier to effect a change in mass and thus the change in gravity that _might_ affect the occurrence of quakes. After all, the work on tidal loading (Vidale, et al) that shows tides can affect certain types of quake zones (albeit by a very miniscule amount) is a gravity effect.

I'm sure I confused a few people.... :)

Brian