Printer Friendly

On shaky ground.

New early warning networks could provide alerts a few seconds before earthquakes hit, as Alexandra Witze described in "Buying time" (SN: 4/19/14, p. 16). These systems work by detecting the primary seismic waves, or P waves, that arrive before the more damaging secondary waves. Reader David Reynolds e-mailed the story of his frightening experience with a magnitude 9.2 earthquake, the second largest in recorded history, which led him to believe P waves could help provide early warnings. "I was at the corner of 15th Avenue and Juneau Street in Anchorage when the Good Friday quake struck in 1964. A week after the quake, I was working in an office with about 20 other people at Ft. Richardson when, without saying anything, everyone in the office suddenly jumped to their feet and started running out of the building. No noticeable shaking had started. About 15 or 20 seconds later, we had a 7.5 aftershock. Although none of us knew what we were experiencing at the time, I'm sure now that we must have been sensing the P waves."

People can absolutely feel P waves, says Witze. "Trained seismologists in particular can detect them and they will start counting as soon as they feel them, to determine the seconds elapsed until the secondary waves arrive. This allows the researchers to calculate a rough distance to the epicenter."

COPYRIGHT 2014 Science Service, Inc.
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 2014 Gale, Cengage Learning. All rights reserved.

Article Details
Printer friendly Cite/link Email Feedback
Title Annotation:FEEDBACK
Publication:Science News
Date:May 31, 2014
Words:229
Previous Article:Building a better vaccine.
Next Article:Virtual universe reconstructs over 13 billion years of history.

Terms of use | Privacy policy | Copyright © 2019 Farlex, Inc. | Feedback | For webmasters