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

The four-day event, called Cascadia Rising, begins 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 as a multi-day earthquake and tsunami drill began throughout the region.

Inslee, standing in front of military and other federal vehicles brought into Camp Murray for the exercise, called the event a "remarkable partnership."

Inslee said that the region needs to be ready for the inevitability of a strong earthquake that could have devastating effects. He said "at some point in the future, we hope in our distant future, it will strike in our beautiful region."

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

Patrick Knouff, Emergency Management Specialist for the Olympia Fire Department, said more than just first responders can learn from Cascadia Rising. He hoped the earthquake exercise will remind the general public to be prepared as well.

"This area is going to be in complete chaos," said Knouff.

Knouff said everyone should have enough food, water and medicine to last at least 72 hours.

Why the three-day supply?

"It may take that long, or longer, for first responders to get to you," said Knouff.

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