The Cascadia Subduction is a 640 mile long fault that runs from Northern Vancouver Island in Canada to Cape Mendocino in Northern California. The fault, a few miles offshore, is created by two plates meeting - the Juan de Fuca Plate and the North American Plate. The fault has the potential to create a Mega Quake which can exceed a magnitude 9.0 on the Richter Scale; an earthquake of this magnitude would likely trigger a tsunami.
On February 6, 2019 the US House of Representatives passed a bill that "requires the Federal Emergency Management Agency (FEMA) to develop a plan for the purchase and installation of an earthquake early warning system for the Cascadia Subduction Zone." The bill, which is known as the "Pacific Northwest Earthquake Preparedness Act of 2019" just arrived in the US Senate and was referred to the Committee on Homeland Security and Governmental Affairs.
As mentioned in a previous post, the most recent earthquake in the Cascadia Subduction zone was in 1700; the frequency is estimated to be every 240 years, making one overdue. Worldwide, fatalities from tsunamis far exceed all other fatalities from natural disasters. Seattle and the Pacific Northwest are vulnerable; hopefully the bill passes and the system is put in place very quickly.