Pathfinder: Shadow of Chernobyl
In 1351 a great explosion of magic erupted from the Chernobyl iron mines.
The blast killed most of those nearby, caused significant damage to the nearby down of Pripyat and created a fallout of intense magical energy within the area that warped whatever it fell upon. Some of the first Chimeras were survivors of this disaster.
After a few years the background magic began to fade sufficiently to allow access to the area and many of the houses and businesses within were broken into and plundered. In 1358 Teodoras Butvydaitis ordered the area to be formally resettled and the mine to be reopened.
Apocryphal tales tell of a vein of magical ore or an object of vast power that had was disturbed by the mining, but no first hand witnesses survived and the mine itself was too infused with magic to ever enter during this resettlement period.
In 1359 there was a Second Disaster that wiped out most of this new wave of settlers.