The Shake Up on Earthquakes
On October 8, 2005 a 7.7 magnitude earthquake hit Pakistan, damaging many areas in that county and in bordering India. More than 30,000 people have been reported dead and scores of others are injured. If you live in the United States, you should be prepared for a quake much like this one. Thousands of quakes happen across the US each year. The good thing is, almost all of them are too small to feel. Most earthquakes in North America happen west of the Rocky Mountains, but there are still 39 states that are at serious risk for quakes.
Earthquakes - Pushy Plates
Quakes are waves that travel through land. The earth's surface is made up of several tectonic plates that are constantly shifting around. Most earthquakes happen along the fault lines where two or more plates meet and become weak from always pushing against each other. Rocks can take the strain from the pressure for centuries, but will eventually snap at the weakest point and shock waves will ripple outward.Earthquakes - Recording Zigzags
A seismograph is a machine that records the ground vibrations during a quake. A needle keeps drawing straight lines until the earth trembles, then the lines start to zigzag. The bigger the zigzags, the bigger the quake. The strength of an earthquake is measured by the Richter scale. Based on the seismograph readings, the Richter scale rates a quake using numbers 0-9, nine being the mother of all quakes.Earthquakes - The Richter Scale
1 - Generally not felt, except by instruments.2 - Generally not felt, except by instruments.
3 - Sometimes felt by people, but no damage.
4 - Sometimes felt by people, but no damage.
5 - Felt by most people, damage near epicenter (where the plates actually smashed into one another).
6 - Damage to buildings within 6 miles (10 km) of the epicenter.
7 - Serious damage to buildings within 60 miles (100 km) of the epicenter. Loss of life.
8 - Major earthquake with damage being caused to a huge area. Loss of life over 120 miles (200 km).
9 - Very rare. Major damage and loss of life up to 600 miles (1,000 km) away.
Earthquakes - Are They Predictable?
So far, scientists have yet to develop a reliable way of predicting earthquakes. There are of course many factors that they believe lead up to earthquakes, like change in groundwater chemistry, foreshocks (small, insignifcant quakes) and strain in underground rocks. Because each quake seems to be caused by a different combination of these factors, it makes it very difficult to make predictions far enough in advance to help people. Seconds before a quake, pets like dogs and cats might get a little freaky, as they seem to be able to feel the trembling well before we do.Earthquakes - What To Do
One of the biggest quake dangers is being hit on the head. If you are indoors, stay put. Place something protective on your head and crouch under a table or stand in a doorway. If you are outside, quickly find an open space and stay away from things that will fall on you. After an earthquake, be prepared for aftershocks. Aftershocks follow earthquakes and are usually smaller than the actual quake. They are dangerous because they can cause things that were weakened in the first earthquake to fall down.Related Stories:
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