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
|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|