Tuesday, December 16, 2008


We are not at work yet, so we do not know how this morning's earthquake has affected the Audubon Center at Francis Beidler Forest.  However, since the old-growth, cypress-tupelo swamp has been there for thousands of years, we doubt that much has changed since yesterday.

At approximately 7:45 a.m. this morning, the ground below nearby Summerville shook.  The 3.6 earthquake only lasted for a few seconds, but there was no mistaking what had happened!  The details can be seen at the U. S. Geological Survey Earthquake Hazards Program.   Check
 out the South Carolina Seismic Network for details of past South Carolina earthquakes.  There are active faults that run below Summerville and the historic plantations along the Ashley River.  Although the area experiences an average of 25 earthquakes a year, most are below the threshold for people to notice.

The image shows earthquakes that occurred in or near South Carolina between 1973 and 2007 and registered 2.0 or higher on the Richter Scale.  Note the cluster of events in the Summerville area. (SCEEP

"Most of South Carolina's earthquakes occur in the Coastal Plain where the rocks underneath are very broken up from the break-up of Pangea (when Africa and North America were one continent!). These cracks in the deep rocks mean that this area of the plate is weak, so if you push on the edge of the plate, some of these faults/breaks will allow the rocks" to move. (SCEEP)

"Seismically, South Carolina been active since the first settlers arrived as shown below on the map of earthquakes that occurred in South Carolina between 1660 and 1986, these earthquakes are based on personal accounts and evidence of damage as well as seismographs in the later years.  However, Charleston is perhaps best known for the earthquake of 1886 which measured as a magnitude between a 6.9 and a 7.3 on the Richter scale and devastated Charleston and Summerville causing massive damage and more than 60 deaths. That earthquake was so large that it was strongly felt as far north as Chicago. The map below shows the 'felt' areas for the Charleston earthquake as notations on the Mercalli magnitude scale." (SCEEP)

...and we thought yesterday's Christmas Bird Count was exciting!

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