In geology, an aulacogen is a failed arm of a triple junction of a plate tectonics rift system. A triple junction beneath a continental plate initiates a three way breakup of the continental plate. As the continental break-up develops one of the three spreading ridges typically fails or stops spreading. The resulting failed rift is called an aulacogen and becomes a filled graben within the continent. However, the crust in an aulacogen region remains weakened by previous rifting activity and thus… (More on Aulacogen)