Earthquakes
Just after 11pm on February 27th, a 4.7-magnitude earthquake struck central Arkansas, serving as a reminder that earthquakes can happen east of the Rockies. Below is a magnitude scale chart that I found at a Michigan Tech site (http://www.geo.mtu.edu/UPSeis/magnitude.html). You can use the chart to see the difference between the Arkansas earthquake and the 6.3-magnitude earthquake that hit Christchurch, New Zealand last week. (A 7.1-magnitude earthquake also struck Christchurch on September 4th.) When was the last earthquake in your state? To find out, click on the following URL from the United States Geological Society: http://earthquake.usgs.gov/earthquakes/eqarchives/last_event/states/.
| Magnitude | Earthquake Effects | Estimated Number Each Year |
| 2.5 or less | Usually not felt, but can be recorded by seismograph. | 900,000 |
| 2.5 to 5.4 | Often felt, but only causes minor damage. | 30,000 |
| 5.5 to 6.0 | Slight damage to buildings and other structures. | 500 |
| 6.1 to 6.9 | May cause a lot of damage in very populated areas. | 100 |
| 7.0 to 7.9 | Major earthquake. Serious damage. | 20 |
| 8.0 or greater | Great earthquake. Can totally destroy communities near the epicenter. | One every 5 to 10 years |
