safety unknown; whereabouts unknown
Used in news or formal contexts when a person's safety or fate is not yet confirmed, often after a disaster or accident.
After the earthquake, many residents are unaccounted for.
Families of the passengers whose safety is unknown are waiting for information.
行方不明 means 'missing' (whereabouts unknown), while 安否不明 specifically means 'safety unknown', often used when someone may be alive but uncontactable.
安否確認 is the act of checking someone's safety, whereas 安否不明 describes the state of safety being unknown.
Compound of 安否 (safety, well-being) and 不明 (unknown, unclear).