Holenesh Canyon was once a settlement, about 500 kilometers north of the Jedi Temple, named for the Jedi who first discovered it. It is a kilometer deep cleft through one of Ilum's many mountain ranges that runs for roughly ten kilometers. At its height, perhaps a hundred individuals, mostly Jedi researchers, lived in the outpost at the center of this canyon. The settlement itself was established to study a curious phenomenon: a naturally reoccurring fluctuation in the Force.
One night, when this fluctuation occurred, there was an earthquake, which set off a massive avalanche. Most of the outpost's inhabitants were killed. The survivors were forced to walk back to the Jedi Temple. Curiously, this earthquake coincided with another occurrence of the fluctuation the researchers were there to study.
The settlement was remote enough that no attempt at recovery or resettlement has been made. The buildings still stand, remarkably well preserved.