noun, noun or participle which takes 'suru'
investigation to determine the cause; tracing back to the origin
Formal noun often used in technical, medical, or accident contexts. Can be used as a suru-verb (原因究明する) meaning 'to investigate the cause'.
事故の原因究明が急がれている。
The investigation into the cause of the accident is being rushed.
専門家チームが原因究
A team of experts worked on determining the cause.