Reading the Richter Scale
How much does the ground shake during an earthquake? Scientists can tell using the Richter (RIK-ter) scale. It measures the shaking on a scale from 1.0 to 9.0. The weakest earthquakes are 1.0, or less. The strongest earthquakes on the scale can measure is 9.0.
California has had many strong earthquakes this century. The recent Los Angeles quake measured 6.6 on the Richter Scale. The biggest quakes in history include a 1960 quake in Chile and the Indian Ocean quake in 2004 which caused a devastating tsunami. Each of these measured about 9.0 on the Richter Scale. See below for a general guide to how this scale works:
Richter Scale
8.0 — Very few buildings stay up. Bridges fall down. Underground pipes burst. Railroad rails bend. Large rocks move. Smaller objects are tossed into the air. Some objects are swallowed up by the earth.
7.0 — It is hard to keep your balance. The ground cracks. Roads shake. Weak buildings fall down. Other buildings are badly damaged.
6.0 — Pictures can fall off walls. Furniture moves. In some buildings, walls may crack.
5.0 — If you are in a car, it may rock. Glasses and dishes may rattle. Windows may break.
4.0 — Buildings shake a little. It feels like a truck is passing by your house.
3.0 — You may notice this quake if you are sitting still, or upstairs in a house. A hanging object, like a model airplane, may swing.
2.0 — Trees sway. Small ponds ripple. Doors swing slowly. But you can't tell an earthquake is to blame.
1.0 — Earthquakes this small happen below ground. You can't feel them.
The Richter scale grows by powers of 10. An increase of 1 point means the strength of a quake is 10 time greater than the level before it. Here's how it works:
An earthquake registering 2.0 on the Richter scale is 10 times stronger than a quake registering 1.0. A quake registering 3.0 is 10 X 10 or 100 times stronger than a quake registering 1.0 A 4.0 is 10 X 10 X 10 or 1,000 times greater than 1.0 and so on.
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