Cone Penetration (CPT), Flat Dilatometer (DMT) and Seismic Shear Wave Velocity tests were conducted in four regions of the New Madrid seismic zone. Test results are compared to existing liquefaction criteria and to surface evidence of liquefaction (sandblows) during the 1811–1812 events. In general, all three tests confirm the presence of liquefaction-prone strata at locations with evidence of liquefaction. A “sand blow index” (SBI), which accounts for both local and regional sand blow intensity, correlates reasonably well against the minimum values of DMT horizontal stress index, the normalized CPT tip resistance, and the normalized shear wave velocity at each test location. An upperstratum clay also appears to play a significant role in inhibiting sand blow formation. Its thickness also correlates well with the SBI.