Kelownan Naquadria bomb

A powerful explosive device capable of leveling entire cities, the Naquadria bomb is a weapon of mass destruction developed by the nation of Kelowna as a last resort to protect them from two rival nation-states on their planet, Langara. When the Andari Federation and Terrania negotiated a peace treaty, Kelowna's leaders believed that an attack would soon follow. Against the recommendations of SG-1 and the scientists who pioneered the device (including Jonas Quinn's mentor, Dr. Kieran), they eventually used it on their enemies. The destruction was immense, but it did succeed in bringing the Andari and Terranians back to the negotiating table -- until the Goa'uld Anubis arrived in force to occupy to the planet. During the early stages of the bomb's development, a laboratory accident nearly detonated a small supply of Naquadriah in an explosion that would have killed millions. The disaster was averted by Daniel Jackson, who in the process exposed himself to a fatal dose of radiation.

In the months that followed the bomb's use, a research team led by Jonas Quinn discovered that the explosion had set off a process deep underground that was transforming ordinary naquadah into a massive vein of unstable Naquadriah, which was threatening to destroy the planet.