崩落 （ホウラク） collapse, break, cave-in, crash, market decline, market crash

崩壊 （ホウカイ） collapse, crumbling, breaking down, caving in, (radioactive) decay, disintegration

壊崩 （カイホウ） collapse, crumbling, breaking down, caving in

崩れる （くずれる） to collapse, to crumble, to get out of shape, to lose one's shape, to become disorganized, to become untidy, to break down, to be thrown into disarray, to crash (stock market), to slump, to decline, to break money into small change, to turn bad (e.g. weather), to change for the worse, to deteriorate

崩す （くずす） to destroy, to demolish, to pull down, to tear down, to level, to disturb, to put into disorder, to throw off balance, to make shaky, to relax (one's pose), to make oneself at ease, to break (a bill), to change, to make change, to write in cursive style, to write in running style, to break into a smile, to let off a smile, to lower (a price)