题目选项分析

A nuclear test explosion detonated recently in the Pacific Ocean created a substantial blast with a yield of 7.3 kilotons; an earthquake with that force would measure as magnitude 5.1 on the Richter scale.

When a nuclear test explosion was detonated recently in the Pacific Ocean, it created a substantial blast with a yield of 7.3 kilotons; qualifying it to be magnitude 5.1 on the Richter scale if an earthquake.