We’ve all waited a long time, and last week our patience was rewarded. Despite rumors of a rushed production schedule (eerily similar to that of the original film), we finally got a full trailer for 2020’s Ghostbusters: Afterlife, complete with the Ecto-1 and some proton pack blasting.
Apparently, six months was too long a wait for Ant-Man star Paul Rudd to hold off spitting out a mixed-accuracy spurt of sci-fi jargon! First it was quantum physics, now earth science!
Seriously, in one sentence near the trailer’s beginning, Rudd’s teacher character gives us four bits to chew on.
Somehow, a town that isn’t anywhere near a tectonic plate, that has no fault lines, no fracking, no loud music even, is shaking on a daily basis.
Lithospheric Slabs Assemble
Firstly … there’s no place on Earth that isn’t on a tectonic plate. The entire crust (and upper mantle, the mushy layer directly beneath it) is broken up into interlocking plates, like a jigsaw puzzle. In the U.S., we sit on the North American Plate. The Pacific Plate, which is mostly covered in oceanic crust, is directly to the west. It’s the slipping of the two past each other that causes California’s largest earthquakes, and the Pacific diving under the South American Plate spurs the growth of the Andes Mountains, the tallest outside of Asia.
Rudd’s character might be forgiven (let’s hope he’s not a science teacher), because when “continental drift” (the precursor to the plate tectonic theory) was proposed by Alfred Wegener in 1912 to explain why many coastlines seem to fit together, the same fossils are found on faraway shorelines, etc., he thought the oceans were unchanging, and it was the continents only that plowed through them (meaning, in a way, not everything was on a “plate”).
But Wegener’s idea didn’t hold water (heh), since the oceanic crust is denser than the continental crust, so pushing the latter through the former would be like trying to shove a piece of paper through a block of wood. Plus, he didn’t have a mechanism for what was doing the “pushing.” It wasn’t until we learned about the constantly churning heat patterns within the Earth that we began to understand the reason for the movement.
Tectonics wasn’t accepted until the plate boundaries were discovered, thanks to seismic networks developed to monitor Soviet nuclear tests. (geo.cornell.edu)
Get cracking
And fault lines are everywhere, too! A fault is just what it sounds like — a break in the subsurface rock. They don’t have to be hundreds of kilometers in length, like the San Andreas. The smallest are only a few millimeters.
They’re not just at plate boundaries, either. Since rocks are brittle and there are always stresses put on them from the movement of the plates, there are plenty of intraplate faults, too. The New Madrid Fault (or, more accurately, the New Madrid Seismic Zone), near the Mississippi River, is square in the middle of the North American Plate, and has been responsible for four of the largest earthquakes on the continent in recorded history.
This region is so unstable due to a failed rift beneath the surface that makes the area “mechanically weaker” than usual, and more susceptible to the slow pushing from the Mid-Atlantic Ridge — a much more successful, continuing rift.
Grease the wheels
There’s a lot of uneasiness and fear surrounding the practice of hydraulic fracturing, better known to most as “fracking.” Fracking involves the high-pressure injection of liquid (mostly water) into subsurface shale beds to increase the interconnectedness of pore spaces in the rock, so that the natural gas within can flow more easily and be extracted.
One concern about fracking is that it makes the gas flow so easily that it can leak out of the ground, and even into water supplies, which might also be contaminated by the fracking fluid itself. Recent studies show these impacts to be minimal, though, as long as the right procedures are followed. Whether every individual crew does things according to standards, though, is another matter.
Okay, but can fracking cause earthquakes? The U.S. Geologic Survey says fracking itself causes only very small earthquakes, so small they can’t even be felt. HOWEVER, when the wastewater is stored in deep injection wells, THAT can indeed, so it seems, produce sizeable earthquakes that can do damage.
Hydraulic attacking
ARE YOU READY TO ROCK?!
And now for the craziest. Loud music could never cause an earthquake … right?
No, not exactly. Really, sound waves are just the compressional movement of air molecules (as interpreted by the ear and brain). Earthquakes cause the same kinds of movements in the particles that make up rocks, but in that case they’re called “p-waves,” as in “primary,” because they reach faraway locations faster than the also produced “s-waves” (which are more akin to the transverse, up-and-down waves you might see on the surface of water).
While even the loudest of music isn’t going to make the Earth tremble, some scientists think the “sonic vibrations” caused by earthquakes can initiate acoustic fluidization, forcing small particles at a fault to behave like a liquid, thus making aftershocks more likely. My parents always said hard music was a bad influence.
AIPT Science is co-presented by AIPT and the New York City Skeptics.
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