Let me preface all of this by stating that I am no scientist. I am pretty handy which is what lead to this discussion between a few friends and myself. We were talking about how it’s amazing that a small amount of weight (1 gram) can throw off the balance of a wheel. As the discussion went on, we started applying that logic to the Earth as a whole.
Between mining ores and minerals, building in different locations, damming rivers/reservoirs, etc. that should translate to a displacement of weight. Would that cause the Earth itself, which spins, to have a wobble, similar to an unbalanced wheel?
This seems so simple, but I haven’t been able to find any research on this specific topic. Does anyone know the answer to this? Or where to look for this research if it has been conducted?
Comments
The Earth has a.mass of 6×10^24 kg, I doubt human movement of mass is more than a rounding errors there.
However, humans moving stuff does have an interesting impact. The constant dredging of the delta by New Orleans to keep shipping lanes open is actually causing a noticeable amount of subsidence. In a sense, humans are literally making New Orleans sink faster.
The 2011 Japan earthquake, for example, shifted the axis by about 16 cm, according to the BBC, Rutgers and other experts.
So the north and south poles shifted 16 cm.
Similar for other earthquakes.. turkey, sumatra..
Especially where land shifts in water. ( Because rock is 3 x more dense)
So Myanmar maybe not so big a change,as its rock vs rock.
> We were talking about how it’s amazing that a small amount of weight (1 gram) can throw off the balance of a wheel.
Because you force the wheel to rotate around its geometric center. Let it rotate around its center of mass (as Earth always does) and you won’t notice any difference from that added weight.
The Three Gorges Dam lengthened days by around 60 nanoseconds because more water was farther away from Earth’s rotation axis once it was filled. That’s a relative change by 0.0000000000007.
The Earth is way bigger than you think, and we occupy basically dust particles on the surface of a globe.
Earth is 5.92 sextillion metric tons. At most we shifted maybe a quadrillion tons. I doubt even that. That’s less than 1/5 millionth the mass of the Earth. The change would be drowned out by other natural processes.
This is first-semester physics stuff.
I’m sure there are examples in the other comments I’m not going to read. I hope someone mentions the Three Gorges Dam in particular.
But in the end, tectonic effects are way bigger than anything Humanity has even come close to causing.
The building of mountain chains, and their subsequent erosion, involves orders of magnitude more change in mechanical moments than anything we’ve accomplished. And they’re infinitesimal compared to the creation and motion of the continents. And there could be motions in the mantle that are just as much bigger than that.
Kinda makes one wonder about big masses of ice moving around.