Scientists Found a 1,700 Mile Crack Across the USA. Here’s What You Need to Know
Is America at risk for Great earthquakes spanning across the full United States? “Cracks Across America”, in Rift zones, may conceal large fracture type faults where scientists may not be able to identify where these hidden fractures may unleash catastrophic earthquakes.
LOS ANGELES, CA (California Network) – In Nov 1981, a study was published that rocked the scientific world, and sparked concern in FEMA circles, in which a 1,700 mile “Crack Across America” was discovered. Worse yet, this crack cuts through the New Madrid Seismic Zone, where in 1811 and 1812 three giant earthquakes devastatingly struck the center of America. Scientists have been struggling, since then, to answer the question of what risk this mega feature may pose to our heartland today. Recently, and less known, is a study from an independent geologic research set of work , that has identified a possible second “Crack Through America” that crosses into and through the same volatile New Madrid Seismic Zone.
The original 1,700 mile “Crack Across America” was found using modern day gravity mapping satellite data, and using computers, to process the measurements . In 1981, Dr. Raymond E. Arvidson of Washington University in St. Louis used data processing techniques where 600,000 discrete gravity measurements, from 20 years of scientific data gathering, to synthesize a map. The results revealed an astonishing ancient rift in the North American crust that extends some 1,700 miles from Idaho to the southern Appalachian Mountains. New discoveries, from more recent research, has extended this “Crack” anomaly in where it combines with a MegaShear  zone to the middle of Washington State and possibly with the Olympic-Wallowa Lineament (OWL)  – which reaches to the Pacific Ocean near Port Angeles Washington. Thus the total length may total nearly 2,200 miles.
This ancient rift, estimated to be a billion years old, was dubbed the “Missouri Gravity Low” in the eastern most section of the “Crack Across America”. Another rift, 60 miles by 30 miles, underlying the Mississippi river valley, called the “Reelfoot Rift”, was found to cross through the Missouri Gravity Low and head to the northeast/southwest. These two rift zones intersect at the New Madrid Seismic Zone. Over 4,000 small earthquakes have been mapped within these intersecting “rift” regions since 1974.
A maverick geologist, Jack Reed, performed a study in mapping the frequency and location of larger magnitude earthquakes trending along the northeast trending lineament of the “ReelFoot Rift”. The resulting data indicated another concerning revelation – that a possible second “Crack Through America” connects the Reelfoot Rift with the well known St. Lawrence rift zone in Canada. Just as the New Madrid Seismic zone revealed its active potential in its “rift zones”, a magnitude 7.9 earthquake, in 1663, struck near Charlevoix and revealed its power in the St. Lawrence rift zone.
Perhaps a partial clue to what may link to the existence and nature of the “Crack Across America” and the “Crack Through America” is the Midcontinential Rift (MCR) System. Research has identified that a movement direction of the MCR, from tremendous intraplate pressure, forced a southern expansion of this large rift, where the southern edge traversed directly towards the New Madrid Seismic Zone. The Midcontinental Rift thus forms a horseshoe that straddles and reaches, by its tips, at or near the two major “Crack” lineaments. Intraplate pressure could be intensified into these intersecting lineaments, including the resulting pressure(s) at the New Madrid Seismic Zone.