The Lumbridge Earthquake was a significant geological event that occurred in Year 169 of the Fifth Age. The earthquake's epicentre is believed to have been in the Lumbridge Swamp, to the south of Lumbridge. The area is noted for being geologically unstable and having multiple earthquakes.
The earthquake did not cause significant damage to any structures on or below the surface, but within the swamps significant subterranean events took place. Parts of the Lumbridge Swamp Caves were exposed, in particular a cavern where Guthix was said to have wept after ending the Gielinorian God Wars.
The re-exposure of the caves ultimately resulted in the rediscovery of the Dorgeshuun cave goblins, who had established Dorgesh-Kaan beneath Lumbridge millennia ago. The quake was responsible for the re-discovery of much of the southern Misthalanian cave network, which is now being explored, mapped, and studied.