Cascadia is what's known as a "megathrust" fault.

2019年12月六级真题（第一套）阅读 Section C

During a megathrust event, all of that stress releases and some of the world’s most powerful earthquakes occur.

2019年12月六级真题（第一套）阅读 Section C

It was caused by a megathrust event as the India plate moved beneath the Burma micro-plate.

2019年12月六级真题（第一套）阅读 Section C