“Seth material” search engine (Jane Roberts)

The second layer, still of the personal subconscious, contains those elements most deeply feared for personal psychological reasons, those which somewhat frequently arise as in an earthquake, to shatter the seemingly solid surface of the ego.

It is from this layer that so-called secondary personalities may sometimes arise, usually due to one of the psychic earthquakes mentioned earlier. As earthquakes cause lava to boil up seemingly from the center of the earth, so do some secondary personalities in their explosive emersion bring with them debris from other levels of the subconscious, often personifying themselves in the guise of those buried and frightening fears that have, until then, found no vehicle for expression.

This phenomena is more common however than you would suppose, though unfortunately in many cases the secondary personality gives personification to buried fears and fantasies that are unhealthy to the dominant personality. Not only this, but because they are released by a psychic earthquake they emerge forcibly and sometimes with more vigor than the present personality can handle, so that they are in a position to dictate terms to the dominant personality.