倒壊 and 崩壊: physical collapse and the collapse of trust
Read 倒壊 for a house or a wall at risk and 崩壊 for part of a stone wall or trust, distinguishing completed collapse, risk, and a condition for prevention.
倒壊 appears with collapse and the risk of collapse
「強い揺れで空き家が倒壊した。」 says that strong shaking caused a vacant house to collapse. 空き家 identifies the physical object, and 倒壊した presents a collapse that has already happened.
「倒壊の恐れがある塀には近づかないでください。」 asks the listener not to approach a wall because it may collapse. 倒壊の恐れ expresses a risk of collapse, rather than saying that the wall has already fallen.
崩壊 applies to part of a wall and to trust
「大雨で古い石垣の一部が崩壊した。」 says that heavy rain caused part of an old stone wall to collapse. 崩壊した is physical here, but 一部 limits the affected object to part of the wall.
「信頼の崩壊を防ぐには率直な対話が必要だ。」 says that honest conversation is necessary to prevent trust from collapsing. Trust, rather than a structure, is the object of 崩壊. 防ぐには gives a condition for prevention; it does not report that prevention has succeeded.
Read the object and extent from the sentence
Both 倒壊 and 崩壊 occur with physical collapse. The vacant house and part of the stone wall are the objects stated in the examples. They do not establish an exclusive rule that 倒壊 always means total collapse and 崩壊 always means partial collapse.
In 信頼の崩壊, 崩壊 is figurative: trust can collapse without a building falling. Physical collapse, a risk of collapse, and a prevention condition provide different information, so read the object together with expressions such as 恐れ and 防ぐには.
Does 信頼の崩壊 refer to a physical structure like a collapsing stone wall, and do 倒壊 and 崩壊 divide total from partial collapse?
Show the answer and why
信頼の崩壊 figuratively describes trust collapsing. Both words also appear with physical collapse; 一部 supplies the partial extent in the stone-wall sentence. The words do not form an exclusive total-versus-partial division, and 防ぐには states a prevention condition rather than a completed result.