* Earthquake Richter 5.0 = 32 kilotons nuclear weapon, like was used at Nagasaki * Earthquake Richter 6.0 = 1 megaton nuclear weapon * Earthquake Richter 7.0 = 32 megaton nuclear weapon * Earthquake Richter 7.1 = 50 megaton nuclear weapon, Tsar Bomba, the largest nuclear weapon ever tested * Earthquake Richter 8.0 = 1 gigaton nuclear weapon, much larger than anything ever made

The meaning of the word nuclear weapon, is a weapon that has a nuclear warhead on it.

You're talking tactical and strategic weapons.

Tactical would be used in the battlefield in the form of smaller rockets or freefall bombs under military situations.

Strategic weapons would usually be a higher yield and are made to threaten a country's population, infrastructure and military; or to cripple the country's ability to wage war.

ICBMs are tactical nuclear weapons. The B61 bomb is a tactical weapon though it does serve a dual role as a strategic weapon.

Nuclear weapons

Nuclear weapons