Earth's magnetic field -- How "suddenly" does it switch?

[zuz]

I know, geologicaly speaking, that "suddenly" is a relative term. So when they say that Earths magnetic field suddenly switches, how long are we talking about. Days, hours, centuries?

 

[trurle]

Several centuries to thousands years actually. Some researches believe the magnetic reversal is already in progress now (see South Atlantic Anomaly)

 

[jim mcnamara]

Link to help @trurle 's point: https://en.wikipedia.org/wiki/South_Atlantic_Anomaly

 

[Ophiolite]

https://www.researchgate.net/profile/Pierre_Camps/publication/236622936_New_evidence_for_extraordinary_rapid_change_of_the_geomagnetic_field_during_a_reversal/links/00b7d518788b1d7062000000/New-evidence-for-extraordinary-rapid-change-of-the-geomagnetic-field-during-a-reversal.pdf discusses the possibility of rapid changes.
From the abstract: "Palaeomagnetic results from lava flows recording a geomagnetic polarity reversal at Steens Mountain, Oregon suggest the occurrence of brief episodes of astonishingly rapid field change of six degrees per day." (Emphasis mine.)
From the conclusions: "This is not to suppose that geomagnetic reversals take place much more quickly than the several thousand years currently supposed, but rather to suggest that polarity transitions may be punctuated by episodes of extraordinarily rapid field change."

(Please note the research is over two decades old.)