Earthquake Summary Poster
Poster of the Northwestern Tennessee Earthquake of 02 June 2005 - Magnitude 3.9
The posters may be downloaded for viewing or for printing on a color
plotter. Adobe PDF (.pdf) format files are provided. Adobe Acrobat 6.0 or
higher is required for viewing the PDF file on a computer monitor and for
printing the PDF map graphic. IMPORTANT: The PDF map graphic was produced
using TrueType fonts; change the following setting to:
Page(Print)Setup<Properties<Layout<Advanced<Graphic<TrueTypeFont<DownloadAsSoftFont
Attention MAC users: If you have problems viewing the pdf files, please download the pdf file and view it in the lastest verion of Adobe Acrobat.
DISCUSSION
EARTHQUAKES IN THE NEW MADRID SEISMIC ZONE
Earthquakes in the central and eastern U.S. are typically felt over a much broader region than in the western U.S. East of the Rockies, an earthquake can be felt over an area as much as ten times larger than a similar magnitude earthquake on the west coast. A magnitude 4.0 eastern U.S. earthquake typically can be felt at many places as far as 100 km (60 mi) from where it occurred, and it infrequently causes damage near its source. A magnitude 5.5 eastern U.S. earthquake usually can be felt as far as 500 km (300 mi) from where it occurred, and sometimes causes damage as far away as 40 km (25 mi).
FAULTS
The network of faults in the seismic zone is buried beneath hundreds to thousands of feet of sand and mud. Four of the largest faults are recognized as alignments of abundant small earthquakes, and movements along two of these faults dammed rivers and created lakes during the earthquakes of 1811-1812. A few more deeply buried faults were detected during oil and gas exploration, and a few small faults are known from geologic mapping. However, many earthquakes occur away from the few known faults, so there must be additional, unknown faults that can generate earthquakes in the seismic zone. Accordingly, the best overall guide to seismic hazard in the New Madrid seismic zone is the earthquakes themselves. |