Given that the “Pacific ring of fire” is a thing and it’s all trenched suggests displacement of tectonic plates away from the Pacific plate.

If the pole flip hypothesis is valid and something triggers induced fluidity in the asthenosphere, during such events, the asthenosphere would conceivably yield very easily to persistent or even fleeting forces.

Churchward’s research suggests that Mu was very flat. Also lot of water weight from the oceans inundating the lands during the pole flip could contribute heavily (pardon the pun) to pushing the land mass down into the asthenosphere.

The other factor at play here is that Mu apparently existed 53,000 years ago and based on Ben Davidson’s research, geomagnetic excursions occur every 6000 years or so, meaning there have been a number of cataclysms between the first one and today that have further shuffled the deck so to speak.