Backwards Earthquakes Gets Dummy

Seismograph record

There might be nothing more pathetic than a freelancer, desperate for pennies, floundering around in completely unfamiliar territory. The sad thing is that, although the situation is pathetic, it's rather common. The result, however, is another chapter in the gigantic volume I like to call The Stupidification of the Internet. Today's chapter was written by Joan Whetzel (a repeat offender) at eHow.com, in an article called "Difference Between a Seismic Wave and a Tsunami."¹ As happens so many times, Joan showed exactly why people who can tell their hineys from holes in the ground have long derided eHow as utterly undependable. Just take a look at the last paragraph:

"....When an earthquake strikes, the seismic waves move outward from the epicenter, like waves in a pond after a rock is tossed in it. The earthquake sends out a ring of P-waves (primary, strong waves) followed by a ring of S-waves (secondary, shallow waves). By measuring the time between the P-waves and the S-waves, the seismic wave speed can be determined. The travel time of the seismic waves can also be determined by finding the distance between the earthquake and the seismometer, then dividing that distance by the seismic wave speed."

OK, dumbass, here's where you went wrong:

1. An earthquake doesn't "send out rings of waves." The different seismic waves all start at exactly the same time: the moment of the shock. The waves travel at different speeds, hence their seeming separation into "rings."
2. Yes, seismologists measure the time between arrival of the P and S waves - but not to calculate their velocity. They already KNOW the velocity - the difference in arrival times lets them calculate the distance to the shock.
3. See number 2: you got it backwards, you blithering idiot! We suggest that you read an explanation written by someone who knows something about the subject!

For her continuing dedication to eHow's stupidification project, we hereby award Joan Whetzel her second Dumbass of the Day. That and three bucks will buy her a grande Americano.

¹ The original has been deleted by Leaf Group, but can still be accessed using the Wayback machine at archive.org. Its URL was    ehow.com/info_8542590_difference-between-seismic-wave-tsunami.html

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