We started an investigation into the incident.

The police are investigating the incident.

Earthquakes, thunder, fires, and fathers are one of the scary things.

He is a world-renowned scholar.

It's not so much a big problem.

Oh, that's right, I remembered what I ate for dinner yesterday.

The Tōhoku earthquake off the Pacific coast, which occurred on March 11, 2011, was the largest earthquake in Japanese history.

We need to conduct a factual investigation on this issue.

We went to the scene for fact-finding.

We conducted a questionnaire survey for the development of new products.