Roan Mountain View

Maps of Eastern United States Earthquakes From 1972-2012

Julia Irizarry || Spring 2011

Julia Irizarry, a undergraduate geology major, worked with me to write a script that produces a large map and two inlaid maps the Eastern US. The map includes all earthquake epicenters > M0 from the Advanced National Seismic System catalog from 1972-2012. Yes, zero magnitude events are still earthquakes! Due to the logarithmic empirical scaling of magnitude, even negative magnitudes are possible. The 2011 M5.8 Virginia Earthquake is highlighted with a gold star on the map. The two most historically dangerous seismic zones are the New Madrid Seismic Zone (near the Tennessee-Missouri-Arkansas tri-state border) and the Middleton Place-Summerville Seismic Zone (near Charleston, SC). The two map insets highlight these seismic zones. In the 40 years of data plotted here there were 13,360 earthquakes (about 334 events per year). Compare this to the southern California map by Collin Ferebee below where the much smaller southern California region shows 405,712 earthquakes in only 25 years (about 16,229 events per year), or the northern California region shows 301,888 earthquakes in 20 years (about 15,094 events per year). So, while the Eastern United States does commonly have earthquakes, about 100-10,000 times more earthquakes occur at an active plate boundary per year.

Map Details and Source Data

The maps are plotted in Mercator projection using the open source and freely-available Generic Mapping Tools. Digital elevation data was converted from the Shuttle Radar Topography Mission (SRTM) and the National Elevation Dataset (NED). The GMT script requires a Bash shell and a number of files to function properly, but we provide the script so that students and other researchers browsing this site can see what the code looks like that created these maps. The maps just scratch the surface of what Generic Mapping Tools is capable of. The pdf file is in vector graphics format, so it is the highest quality; however, the pdf is 103 Mb, so be patient when downloading and opening it! I recommend right clicking on the file and selecting "Save Link As..." to save the file to your computer. This should prevent your browser from timing-out during the download. Alternatively, we have also provided a smaller rasterized PNG image. See below for download links.

East United States Seismicity from 1972-2012