MadSci Network: Earth Sciences |
Paul - You've posed some interesting problems! I am a geologist/geophysicist, and have worked with some dimensions of these sorts of problems, but cannot answer all of your questions knowledgeably. Magnetics: This one is the farthest afield for me, but my guess is that moving large masses of magnetic materials around (for example, moving iron from ore deposits to end uses like building cars, and then having them move around on Earth's surface) will cause measurable perturbations to the magnetic field you measure locally. That is, a magnetometer will sense the proximity of large metallic bodies. However, in the "big picture," these changes will do virtually nothing to the global magnetic field, as it is a consequence of processes in Earth's core --- things happening on a vastly greater scale and involving vastly greater masses of material than anything mankind can perturb significantly. Earthquakes and volcanoes: Again, I doubt that vehicle activity could ever be correlated with natural hazards. You might think that earthquake and volcanic activity are controlled by stresses within Earth's crust --- that is, what is the pressure (due largely to the weight of overlying rocks) on a fault plane or a magma body, what kind of shearing are these areas subjected to, etc.? The disturbance due to cars moving around is very tiny compared to the stress levels in the Earth's crust. Moreover, it turns out that those loads on the surface don't affect things very deep, so they don't do much to deep crustal areas where earthquakes and volcanoes are originating. However, interestingly enough, there is mounting evidence that very tiny stress changes can indeed "push the crust over the edge" and cause failures like earthquakes and eruptions. For example, I worked with a researcher in Washington who found that Mt. Rainier apparently erupted shortly (geologically short, anyway!) after the last glacial retreat, and he speculated that the removal of the ice load on top of the mountain was enough to "uncork" the mountain, and trigger an eruption. If that proves to be true, your instincts about cars may be on the right track! One other thing about moving cars.... Years ago, I heard of speculation that cars passing each other on the highway tend to create vortices (spinning counterclockwise in the US where we drive on the right) that might then grow and increase tornado activity. Someone tested this idea by looking at the frequency of tornadoes during World War II, when there was strict gasoline rationing, and driving was way down from pre- and post-war levels. This study did find that tornado frequency seemed to be up in that era. However, I believe that serious scientists doubt the significance of this result ---- That is, people who understand the fluid dynamics of atmospheric vorticity don't buy the idea that cars can change things significantly; also, statisticians would point out that the data are too few to conclude with confidence that the correlation of amount of driving with number of tornadoes is meaningful. I hope this helps some with your questions.... You have good insight into what makes nature work! Keep it up! Best of luck, Dave
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