BrainStuff Classics: Does Earth's Crust Have Its Own Tides?

and fall multiple times every day. The effect can be quite dramatic. On certain days, there's a fifty three ft that's sixteen meter difference between the low and high tides in Canada's Immunis Basin Inlet. For example, working fishermen, divers, and ship captains must take fluctuations like these into account. For this reason, government's released tables that predict the heights

of future tides four different corners of the oceans. Yet, unbeknownst to us, the ground beneath our feet experiences tides of its own. The phenomenon goes by many names, including land tides, crustal tides, earth tides, and more. Specifically solid Earth tides. No matter what you call the process, it's caused by the same forces that generate our better known oceanic tides. Tides are complicated beasts. They are the result

of several different factors all working together. The most significant contributing forces are the gravitational pulls that the Sun, Moon, and the Earth exert on one another. The Sun actually has less influence over our tides than the Moon does, despite being twenty two million times larger. That's because the Moon is so much closer to Planet Earth. As such, on the surface of Earth, the Moon's gravitational force is

about two point two times stronger than the Sun's. High ocean tides, at least in most parts of the world, happened twice a day. We experience one when the Moon is overhead, and, counterintuitive as it may sound, a second tide tide takes place when the Moon is on the opposite side of Earth. Low ocean tides occurred during the periods between these two points. The centrifugal force of our

rotating planet helps account for this strange bulging effect. While this is happening, a similar cycle unfolds within the very crust of our planet to a minuscule degree. The ground level itself rises and falls every day in accordance with the moon's whereabouts. We spoke with Duncan Agnew, a geophysicist at Scripps Institution of Oceanography at the University of California, San Diego. He said the motion extends through the whole of the solid Earth, not just the crust, but is

largest at the surface. The earth is slightly elastic. Your naked eyes all that's required to watch the ocean tide come in and go out. However, it's straight up impossible to observe solid earth tides without using scientific instruments. At high tide, New York City can rise upward by fourteen inches that's about thirty six centimes. The Big Apple then

falls by the same degree at low tide. A pedestrian standing in Times Square or the Bronx wouldn't notice any of this, though, because all of the buildings, trees, streets, and people in the Five Burrows rise and fall in concert. Though that's just one example. Acnew says that the vertical motion at the surface varies from place to place. Some areas bulge and descend less dramatically than New York does

other locales outperformed the Big City on that score. Okay, so far we focused on how the Moon affects both solid Earth and oceanic tides, but the Sun should not be ignored in this discussion. Those who live in coastal areas are well aware of how solar activity can affect the strength of oceanic tides. When the Sun aligns with the Moon, the seas high tides get higher and the

low tides get lower. The exact opposite happens when those two celestial bodies are situated at right angles to one another, meaning the planet ends up with low high tides and high low tides. That cycle repeats itself every two weeks and is therefore known as the Fortnightly cycle. On top of giving voters headaches, it also affects sol at earth tides.

Nicholas vander Elst of the U S Geological Survey was the lead author of a sixteen study that investigated the link between the Fortnite cycle, land tides, and seismic activity along California's San Andreas Fault. He said via email, when the Earth's crust flexes in the direction of the title pull, this puts a stress on any tectonic faults that cut through the rock. If the combination of the title stress and the pre existing tectonic stress is just right, this

can set off an earthquake. For that steen research effort, vander Elsts group compared eighty one thousand San Andreas earthquakes. They found that the rate of low frequency quakes increases right before the fortnightly cycle enters its solar lunar alignment stage. But Californians shouldn't lose too much sleep over this news development. The earthquakes in question are too weak and occur too far below the planet's surface to cause any serious damage

on the surface. Crystal tides vander Eilst notes are generally quote far too small to matter for most faults. Nonetheless, the geologist has found that it's possible to observe a small but measurable influence in some locations, particularly in places like mid ocean ridges. There are also special regions of the Earth's crust where fault lines appear to be astoundingly weak. These regions tend to be deep at the roots of subduction zone faults, like the faults that dive beneath Japan

and the U. S Pacific northwest. Down there, some twelve to eighteen miles or twenty to thirty kilometers beneath the planet's surface, faults create small scale seismic tremors. Van Dryilst said the tides can have a very substantial effect on tremors, with tremor rates oscillating by up to thirty percent in phase with the tides. However, these tiny pseudo earthquakes are totally undetectable by people and do not pose any hazard. Still,

it's pretty fascinating. Oh and hey, the ocean is not the only body of water that experiences its own tides. Lakes undergo them as well, but on a much smaller scale. For example, the mightiest tides on North America's Great Lakes are only five centimeters that's zero point four inches in height. Today's episode is based on the article Rising Rock Earth's press has its own tides too, on house touff Works

dot com. Written by Mark Mancini. Brain Stuff is production by Heart Radio in partnership with house Toffworks dot Com, and it's produced by Tyler Clay. Before more podcasts my heart Radio, visit the i Heart Radio app, Apple Podcasts, or wherever you listen to your favorite shows,