Showing posts with label Mercalli Scale. Show all posts
Showing posts with label Mercalli Scale. Show all posts

August 24, 2011

3 Things You Didn't Know About Earthquakes

Many of us at Enslow Publishers end up with massive piles of books in our workspaces. When the earthquake hit, I was pleased to see that my own tower of books swayed from side to side, but did not collapse. In honor of this (relatively) unusual event, I would like to present you with:

3 Things You Didn't Know About Earthquakes!

Alvin Silverstein, Virginia Silverstein and Laura Silverstein Nunn

ISBN 978-0-7660-2975-0

1. There are two very different ways that Earthquakes are commonly measured: The Richter Scale and the Modified Mercalli Intensity Scale. The more familiar Righter Scale measures the energy released by an earthquake, while the Modified Mercalli Intensity Scale measures the earthquake's effects, not its actual power. Any earthquake can have only one Richter scale rating, but it can have many Modified Mercalli Scale ratings: this is because a Mercalli Scale measurement can be given for any place where the effects of the earthquake was felt, while the Richter Scale measurement is only given for the earthquake itself.

2. The first seismograph, an instrument for detecting earthquakes, was invented in 132 A.D. by Chang Heng, a Chinese scholar. While modern seismographs can display the intensity of an earthquake's seismic waves, Chang Heng's seismograph would show an observer the direction that an earthquake came from. Chang Heng's seismograph consisted of a pendulum surrounded by eight dragon heads, each with a ball in its mouth. Each dragon head had a corresponding toad statue with an open mouth under it. When an earthquake hit, the pendulum would swing in the direction that the earthquake came from and knock a ball into the toad's mouth under it. An observer could see which toad statue had a ball in it and know that the earthquake came from the direction it pointed in.

3. Scientists are still unable to accurately predict earthquakes. While methods for measuring earthquakes have improved, and though the forces that cause earthquakes are well understood, there are still no methods for accurately predicting an earthquake.

If you'd like to know more about earthquakes, or many other natural disasters, check out our series: "The Science Behind Natural Disasters".