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