I have covered this before, but Dr. Salla puts this theory for a POLE SHIFT trigger in a new light when he compares explanations from three different books (all must-reads for anyone like me who is fascinated with pole shifts)

Massive Pole Shifts are Cyclic according to Declassified CIA Document

“The Adam and Eve Story” authored by “Chan Thomas”, which was classified by the CIA at some point after its 1963 publication, and declassified in part on June 24, 2013 with the release of a sanitized digital version on the CIA’s website. Thomas’ analysis of cyclic pole shifts was different in key respects to what was being proposed at the time by Charles Hapgood in his seminal book, The Earth’s Shifting Crust (1958).

…Hapgood wrote of a pole shift of up to 40 degrees that could recur every 5000 years or so in The Earth’s Shifting Crust where earlier geographical poles would wander on the Earth’s surface with each crustal displacement.  Instead, Thomas wrote of a massive shift of almost 90 degrees  that would move both poles into the tropics in less than a day, and then back to their earlier polar positions after the next cycle: “…ice ages are not a matter of advancing and retreating ice; it’s simply that different areas of the Earth are in polar regions at different times.”

“… a 1994 book titled World in Peril about the once classified information provided by an Arctic polar explorer, Major Maynard White, who told his son, Ken (the book’s author), about secret Pentagon meetings in 1948 where suppression of evidence of cyclic pole shifts was discussed:

At one of the scientific meetings that Major White attended in the Pentagon in early 1948, the scientists discussed the advisability of alerting the public to the pending polar-flip phenomenon. None of the scientist would agree to withhold the information from the public, but, on the other hand, neither could they agree on how to release it. The knowledge of this phenomenon, some felt, could in itself destroy the moral fiber of society…”

“…Albert Einstein, who wrote the preface to Hapgood’s 1958 book, believed that the accumulation of ice at the North and South poles would be the trigger for a crustal displacement (geophysical pole shift). Einstein explained the triggering mechanism as follows:

In a polar region there is continual deposition of ice, which is not symmetrically distributed about the pole. The earth’s rotation acts on these unsymmetrically deposited masses, and produces centrifugal momentum that is transmitted to the rigid crust of the earth. The constantly increasing centrifugal momentum produced in this way will, when it has reached a certain point, produce a movement of the earth’s crust over the rest of the earth’s body, and this will displace the polar regions toward the equator.”

“…In contrast to Hapgood, Thomas believed the explanation was that something in the Earth’s interior was occurring that was the triggering mechanism.”

“…In World in Peril, the triggering mechanism is described as a flip in the Earth’s magnetic field as cited by Davidson:

It was determined through repeated experimentation that as the “magnetic pole approached the “geographic pole, the “magnetic” pole would at some point accelerate its rate of convergence as though pulled toward the “geographic” pole by centripetal force and jump to coincide; but instead of the poles coinciding, the “magnetic” pole would rapidly “flip” around the “geographic” pole, them spin off towards the equator as though by centrifugal force, ending up at a position where the two axes assumed an approximate 89-degree divergence. After this polar “flip” occurred, the axes would then gradually begin to reconverge over a long period of time.

According to the classified information received by Major White and his USAF Arctic reconnaissance unit, the magnetic pole flip would be the trigger for a crustal displacement leading to an almost 90 degree geophysical pole shift, as explained in the description to the World in Peril:

World in Peril … provides an explanation, based on the unit’s findings, of how Pentagon scientists determined our globe has evolved in prehistory, and how another earth-reshaping cataclysm is imminent!  Now we can understand why mammoths and mastodons found in the arctic permafrost had been instantaneously frozen with subtropical vegetation in their mouths and stomachs.  World in Peril may be the only book in print that accurately explains the elusive triggering mechanism for the phenomena known to scientists for over 200 years as “crustal shift,” and what it implies.

It’s important to emphasize the complementary nature of the triggering mechanisms found in Thomas’ The Adam and Eve Story and White’s information in World in Peril.”

Many people have different theories on causes, triggers, and the length of the cycle – the time between pole shifts.  I could point you to clues that suggest the next catastrophe is due in December of this year (2019) to October 2046 and to several dates in between.  I lean towards the earlier dates due to Bible prophecies suggesting that the generation that sees Israel grow as a nation will see all end times prophecies fulfilled.  From geology and astronomy to Nostradamus and Bible prophecy, many sources point to the next catastrophic pole shift in the early 21st century.