Fig. 1

The New Madrid Seismic Zone (NMSZ). a Seismicity in the NMSZ from the full CERI catalogue²⁷ (grey points), highlighting those since 1 January 2000 (black points). Yellow circles are the approximate locations of the 1811–1812 earthquakes. Earthquakes are scaled by magnitude. Blue and red boxes outline the approximate areas of the NMSZ and the Reelfoot fault, respectively. Other symbols indicate the river gauge at New Madrid (orange triangle), and continuously operating GPS sites in proximity to the NMSZ (blue circles). b Peak-to-peak variation in annual surface load from satellite gravity data, expressed as equivalent water height in millimetres