Scientists are sounding the alarm after a series of earthquakes rocked the West Coast last week, warning a major seismic event is 'inevitable.'
Earthquakes trigger tsunamis by causing the ocean floor to rise or fall, pushing water above to form a massive wave.
But it isn't just California at risk, Washington sits along the Cascadia Subduction Zone that is capable of a 'megaquake', they said.
Harold Tobin, director of the Pacific Northwest Seismic Network, said: '[The] 700-mile long fault capable of producing earthquakes up to magnitude 9 and tsunamis that will impact the entire coast.'
The quake and resulting tsunami could be devastate the Pacific Northwest, killing an estimated 14,000 people and injuring more than 100,000 in Oregon and Washington, according to the Federal Emergency Management Agency.
The Cascadia Subduction Zone -that stretches from northern California to the Pacific - last released a 9.2 magnitude 'megaquake' in 1700, and pressure has been building since.
The Oregon Department of Emergency Management (OEM) states there is about a 37 percent chance that the Cascadia Subduction Zone will produce an earthquake of magnitude 7.1 or greater within the next 50 years.
Robert Ezelle, the director of Washington state's emergency management division, said: 'It's going to be the worst natural disaster in our country's history.'
'Washington has, second only to California, the greatest risk from earthquakes in the country, Tobin told KIRO7.
That is because the state its on active faults and fault zones, making seismic events inevitable.
Along these faults, 'the earthquakes might be smaller, but the damage could be really much worse,' Tobin said.
Large earthquakes produced by these faults would likely cause mass property destruction, cut off access to certain neighborhoods and lead to numerous injuries and even deaths.
'One would expect the power to be down, natural gas lines to be broken, maybe water and sewer lines to be broken,' Tobin said.
He told NBC News that if a major quake were to hit the Cascadia shaking would last five minutes, but tsunami waves would batter the coast for 10 hours.
Roads and bridges would be destroyed, along with some 620,000 buildings and about 100 hospitals and 2,000 schools.
'We're unprepared,' Ezelle said, noting that residents would have to take care of each other due to Washington officials say they'd have to fend for themselves for at least two weeks.
And in California, the most recent large earthquakes did not stem from the San Andreas Fault, but the Salt Wells Valley and Paxton Ranch Fault Zones.
This magnitude 6.4 foreshock and magnitude 7.1 mainshock cut power to at least 3,000 residents in Ridgecrest and caused a total of 50,000 people to feel shaking.
That suggests a damaging earthquake can come from practically anywhere along the West Coast.
Both the San Andreas Fault and the Cascadia Subduction Zone are long overdue for a major earthquake.