There was another earthquake this morning in Haiti, centered about 35 miles WSW of the devastated city of Port-Au-Prince. This aftershock of last Tuesday's 7.0 tremor was measured at a magnitude of 5.9 and a depth of 6.2 miles. While it was closer to the surface of the earth compared to last week's earthquake (remember, the more "shallow" the depth of an earthquake the higher the potential for significant damage), there have not been any reports of any significant additional damage to the area or loss of life.
By the way, the difference between last week's earthquake and this week's is not as simple as saying "it was 1 degree of magnitude weaker than last week's". Actually, this morning's earthquake was actually a bit more than 10 times weaker in shock amplitude compared to last week's. The Richter scale works on something known as a logarithmic (power of 10) scale... that means a 7.0 earthquake is ten times stronger than a 6.0 earthquake, and a 7.0 earthquake is forty times stronger than a 3.0 earthquake. Further, the difference in energy released between a 7.0 and a 6.0 earthquake is even more vast -- and the energy release is roughly equivalent to the damage you can expect. A difference in magnitude of just 1.0 makes the destructive power of a 7.0 earthquake approximately 32 times that of a 6.0 earthquake and a difference of 2.0 (say a 7.0 vs. a 5.0) is around 1000!
For more information, check out the US Geological Survey web site: http://www.usgs.gov.
Brian
