[1] Headed north-south, Cascadia Channel initially formed on the eastern flank of the Juan de Fuca Ridge, which was actively spreading.
At this time, apparently the channel built up by turbidity current that proceeded south, along the western part of the Cascadia abyssal plain, also from the west of the Astoria Fan.
Geologic evidence for the occurrence of earthquakes on the Cascadia subduction zone is off Oregon and Washington, and includes sedimentary deposits that have been observed in cores from deep-sea channels and abyssal fans.
There is a consistent number of turbidites in core samples from both side and main channels, indicating that each turbidity current was likely caused at the same time, by the same event which may be the 1700 Cascadia earthquake.
[5] Ash from the eruption of Mount Mazama, which gave modern-day Oregon its Crater Lake, reached Cascadia Channel via the continental shelf and submarine canyons.