Why my hardwood floor is buckling
The cause of buckling in hardwood floors is nearly always from failure to leave adequate space (generally concealed under trim) at the sides of the room.

Wood shrinks and swells as the humidity changes with the seasons, and mostly across the width of the boards (very little end to end.) If installed without adequate space to allow for this to occur the floor will buckle when it's reached the walls and swells/expands more.

If in addition to normal seasonal changes you have excessive moisture, the "normal" expansion space may prove inadequate.