Reed, this time reflecting himself, has a more technical explanation.
“Simply stated, the linear Cretaceous shelf edge was the separation point of the Gulf of Mexico plate from North American plate,” he said.
According to Reed, this movement started near the end of the Early Cretaceous and, to date, the plate has moved south. The exterior salt basin was formed in the ever-widening gap between these plates by allochthonous salt pressure
(lots on this in Google about the Gulf!!) forced from under the moving plate into the gap.
The trailing edge of this south moving plate is undergoing tensional forces accompanied by outward and upward moving salt into the basin, Reed explained, which creates fractures (faults) along the trailing edge of the plate and these fracture lines are filled with the highly pressurized salt.
This movement, in turn, separates fault blocks from the moving plate, which are then suspended in the ever-expanding exterior basin salt mass. This action, or something very similar, is the source of 11 earthquakes that have struck the northern Gulf, according to Reed. Seven of these quakes are located along the trailing edge of the south moving plate.
“This action, or something very similar, is the source of the earthquakes that occur in the northern Gulf,” he said.
Moreover, for Reed the quake may help prove the existence of plate movement, and could be a new piece of evidence for a tectonically active Gulf.
“This MS=5.2 quake alone does not prove the Gulf is active,” he admits, “but when it is placed in line with other evidence, it’s a major nail supporting the active Gulf structure.”
Reed, who is retired and admits he is not an expert on earthquakes, has theorized for years there was an active tectonic plate in the region that, among other things, is connected to the New Madrid seismic center. This active seismic center is located on a possible tensional continental spreading fault zone that parallels the Appalachians and connects with the St. Lawrence seismic center, located in Canada (see November 2002 EXPLORER).
https://aapg.org/explorer/2002/11nov/rift_zone.cfm
Triple Threat?
The Cretaceous Shelf Edge along with the Suwannee Strait and the West Florida Escarpment, according to Reed, appear to be part of a triple juncture centered on the DeSoto Canyon High.
"The DeSoto Canyon High is one of the largest and most significant structures found in the Gulf," he said, measuring 137 miles by 60 miles, with over 7,000 feet of structural relief at the top of the Paleozoic.
"The Cretaceous Shelf Edge, the Suwannee Strait and the West Florida Escarpment all traverse different areas of the Gulf," he said, "but they each appear to have evolved during the same general time period and they all radiate from the central DeSoto Canyon High. This alignment would be similar to triple junctures found throughout the world."
The Suwannee Strait is a shallow Upper Cretaceous depression that extends across southern Georgia and northwestern Florida for over 200 miles. Reed said several theories have been proposed to explain the cause of the feature, but as one geologist indicated it has been easier to infer the existence of the strait than to account for it.
According to Reed, a northeastward linear projection of the Suwannee Strait would extend the feature to the earthquake cluster zone 20 miles inland from Charleston, South Carolina.
The West Florida Escarpment, the third element of the DeSoto Canyon triple juncture, has been described as a simple carbonate bank build-up. While Reed acknowledged that is true, age dating of samples collected during deepwater dredging along the escarpment indicates the feature is comprised of peritidal and lagoonal limestones with back-reef faunal assemblages deposited under restricted, low-energy conditions.
"If the steep slope face is made up of back reef material, then the question arises of where the fore-reef and the reef complex are located," he said. "It would be unlikely that equal erosion occurred over the entire escarpment, removing only the fore-reef and reef complex and leaving the back-reef.
"It would appear that some other method," he added, "such as transform shear motion, was responsible for removal of the main part of the reef complex."
Asked whether we will see a significant quake along New Madrid, he says, “It’s not a matter of if, but when.”
He is the first to admit, though, that his theory is in stark contrast to others -- and still something of a novelty.
“I developed the active tectonic theory and then realized that this theory would be opposite from the passive theory, and, therefore, I would have an uphill battle trying to prove it,” he said.
“The passive theory (no tectonic activity) has been accepted in our geological community for decades,” he said, “and very few earth scientists would like to change their position. I know I wouldn’t.”