A few events have been considered to be the origin of the earthquake
- The X-Club traveled back in time to 1906 to understand the origins of Mutants. The Hellfire Club was operating in the city at this time and used psychic to learn more about the birth "Over-Men" the next stage in human development. The X-Club came to collect DNA samples from Doctor Nemesis' parents. When they arrived they learned Dr. Nicola Bradley and his wife Catherine Price had been working on a new energy source. The Hellfire Club kidnapped to use the energy source to power their new Sentinel. The X-Club came to their rescue but the battle between the Hellfire Club's Sentinel and the X-Club caused the earthquake.
- A group of Mole Men planned an invasion of San Francisco during this time, they borrowed underneath the city causing an earthquake and produced multiple fires. The Mole Men figured that the citizens must have thought to destroy their city rather then have them take it over. They retreated back underground.
- During the earthquake the Dreaming Celestial ’s chamber was damaged. The Eternals arrived and formed Uni-Mind to fix it. In an apparent manifestation of Mahd Wy'ry, Sprite realized he could use the Celestials powers to change his Eternal life, allowing him to finally grow up.
The immortal being known as the Forever Man was in San Francisco during the incident and was killed and later resurrected in the flames. Now a teenager again he was given the name "Morgan MacNeil Hardy" and considered the city his home and wished to return it to it's prominence before the quake.