dilapidated, ruined
垝 centers on structural decay: something dilapidated or ruined, often referring to a wall or earthen structure that has collapsed.
垝 combines 土 (earth) with 危, which likely contributes both sound and the idea of danger or instability, suggesting an earthen structure that is crumbling or ruined.
The left side 土 is earth, and the right side 危 suggests danger. Picture an old earthen wall that has become dangerous and dilapidated, ready to collapse.
For キ, imagine a key-shaped crack running through a ruined earthen wall: key -> キ, and the wall is dilapidated.