Turn on the NMSZ Structural Features overlay and double-click it to fly to the Missouri, Illinois, Kentucky, Arkansas, and Tennessee area (if you would like to see modern seismicity, turn on Gallery > Earthquakes in the Layers panel as well). This area is well within the North American Plate, yet it has a surprising number of earthquakes (the densest region of earthquakes is referred to as the New Madrid Seismic Zone, which helps delineate the Reelfoot Rift (black lines), a continental rift that failed to continue to extend to form a plate boundary...such failed rifts are called aulacogens). The NMSZ was the site of three large (-7.0 to 7.5) earthquakes (and one major aftershock) from December 1811 through February 1812. 16. Intraplate Earthquakes - New Madrid, MO. With the NMSZ Structural Features overlay on, you should note three distinct segments of the NMSZ: New Madrid North Zone (--Paducah, KY to New Madrid, MO), Reelfoot Central Zone E & W (-Bernie, MO/New Madrid, MO to Dyersburg, TN), and Blytheville South Zone -Caruthersville, MO to Marked Tree, AR). What is the dominant trend/pattern of earthquakes in the north (yellow lines) and south (green lines defining the Blytheville Arch) zones? a. E-W
b. N-S
c. NE-SW
d. NW-SE