Seismic Waves for Dummies

Seismogram

Mistakes happen. Here at the Antisocial Network, we freely admit that's true – why, one of us made a mistake just a couple of months ago! We understand that. What we don't understand is sharing your mistakes because you're too eager to pick up a few more pennies, and doing the research would slow you down: that's the mark of a dumbass. Take Daniel, who calls himself ColonelD at InfoBarrel.com: he laid out his laziness for all the world do see in "Seismic Wave Types."¹

Daniel's level of dumbassery is fairly low at the beginning; more along the lines of "I can't write for crap" than giving you a sense of "I'm an idiot freelancer." He opens by telling us that

"If I were sitting at my desk and an earthquake hit me there would be quite a few different shakings I would feel... When an earthquake occurs, there are two different seismic wave types that I would feel."

The Antisocial Network's house grammarian wasn't much impressed by Daniel's nounification of a gerund ("shakings") in the sentence, nor was the house mathematician particularly happy that he seems to believe that two is "a few." But that's nothing compared to the indignant squawk the house seismologist uttered upon seeing Daniel's count of types of seismic waves. You see, "two" is flat-out wrong.

Daniel gets to that count by telling us that

"The first waves that would hit me are called P waves. These P waves, or body waves, travel through the Earth’s body, not on the surface."

which is basically correct, though he doesn't mention that P stands for "primary" because these waves arrive first. Where Daniel gets it wrong is

"The next seismic wave type that would hit me would be S waves. The time between the P waves and S waves can vary, but for the sake of argument let’s say there’s a two-minute gap. S waves, or surface [sic] waves, travel along the surface of the Earth and are responsible for most of the damages caused by earthquakes..." Ummm, in a word? No. S stands for "secondary," not for "surface." The second waves to arrive are shear waves that also travel through the body of the earth. Since the motion caused by S waves can't be transmitted by non-solids, they don't propagate through a liquid medium. That's how we know the earth's core is (in part) liquid: there's a shadow zone on the opposite side of the earth from a quake where no S waves arrive. The real surface waves come later and their strength diminishes proportional to the distance from the epicenter of the quake.

The remainder of Daniel's content is more or less accurate (though written at approximately the level of a sixth-grader). But omitting one of the three main types of seismic waves and saying nothing about the damping effect of distance? Those are definitely worthy of the Antisocial Network's Dumbass of the Day Award!

¹ InfoBarrel has recast itself as a "green" site and removed all the user-generated content. YOu can, however, still read Daniel's post by using the Wayback machine at archive.org. Its URL was   www.infobarrel.com/Seismic_Wave_Types

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