The Pacific Northwest kicked off a massive earthquake and tsunami drill as part of a multi-day event to rehearse scenarios on how the region would deal with a dual natural disaster.

The four-day event, called Cascadia Rising, started Tuesday.

Federal officials say about 20,000 people will be involved in the disaster drill, representing various federal agencies, the U.S. military, and state and local emergency response managers from Washington, Oregon and Idaho, Native American tribes and emergency management officials in British Columbia.

One main goal of the exercise is to test how well they will work together to minimize loss of life and damages when a mega-quake of 9.0 rips along the Cascadia Subduction Zone and unleashes a tsunami.

More than 8 million people live in the zone, which contains the most heavily populated areas of the Pacific Northwest, including Seattle and Portland.

Washington Gov. Jay Inslee says the Northwest needs to be "as prepared as we can be" for a devastating earthquake.

Inslee was joined by Major General Bret Daugherty, commander of the Washington National Guard, and FEMA Region X Administrator Ken Murphy at a news conference Tuesday.

By running through the scenarios well in advance, he said the state can better prepare and identify potential weaknesses.

In the Eastern Washington region officials will be conducting "table top" drills. Grant County's Kyle Foreman says Moses Lake International Airport is one of the longest runways in the nation and will be used for incoming relief flights.

Emergency officials hope to find holes in response so they can streamline effectiveness when and if the emergency does happen.

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