A shift in the plates that lie beneath an area known as the Cascadia Subduction Zone along the coast of the Pacific Northwest could send shockwaves across the 600-mile fault line. Assistance and services may be delayed by at least two weeks.

Experts estimate 13,000 people will die initially, another 27,000 injured and responders will need to shelter 1 million people and feed another 2.5 million.

There’s a one in three chance that this will happen in the next 50 years, experts predict.

Another tectonic bump, near the middle of the country, in a place called the New Madrid Seismic Zone at the nexus of Arkansas, Missouri and Tennessee, could see 3,500 initially dead, another 80,000 wounded and 7.2 million people displaced, 2 million of them needing shelter.

Researchers have estimated a 25 to 40 percent chance this will happen at some point in the next 50 years.

The devastation of Hurricane Katrina in 2005 was called the largest diaspora of people in the history of the United States.

An estimated 1 million people were displaced, nearly 2,000 died and its effects tied up emergency services and subsequent aid for months.

The first two examples would qualify as emergency experts’ worst nightmare, known as either a “catastrophic incident” or “complex catastrophes,” depending on whether they wear a suit and tie or camouflage.

Planning for the worst

A panel of Army generals and federal officials who are tasked with thinking about such incidents spoke at this week’s Association of the U.S. Army Annual Meeting and Exposition.

“We haven’t had a complex catastrophe,” said Damon Penn, assistant administrator for response at the Federal Emergency Management Agency.

Penn said experts have run scenarios on what would be needed to effectively respond to a catastrophe that saw 100,000 casualties and 1 million people needing some kind of help.

The medical need alone is staggering.

“If every doctor in the United States responded, we still don’t have enough doctors,” he said.

And while managing those disasters and aiding the civilians caught in them is actually delegated largely to the local areas, it will be Army entities such as the Army Corps of Engineers, U.S. Army North and the units of the Army National Guard to provide much of the resources and manpower.

Hurricane Maria, which pounded Puerto Rico in 2017, killed more than 3,000 people. Responding to that disaster required 60,000 military personnel and Transportation Command flew 3,000 sorties in 60 days, said Robert Salesses, deputy assistant secretary of defense for homeland defense integration.

The natural disasters are not the only ones these groups must handle.

Lt. Gen. Laura Richardson, commander of U.S. Army North, noted that part of her responsibilities include having Chemical, Biological, Radiological, Nuclear, or CBRN, troops on hand to respond to a mass attack of that kind within three to 12 hours.

Mass casualty drill going to major cities

This past summer, the Guard, primarily Task Force 46 out of Michigan, continued its three-year annual exercise for responding to a mass casualty attack, chemical or nuclear, in Detroit.

That exercise will rotate to other major cities in the coming years to build partnerships and planning with local, state and other federal agencies.

In part, that’s a reflection of lessons learned from other disasters.

Maj. Gen. Patrick Hamilton, 36th Infantry Division commander, noted that before Hurricane Katrina, many state leaders didn’t quite understand what the Army could provide.

“They started asking for stuff,” he said. “They didn’t really know how much but started asking for ‘stuff’.”

For example, he said he’d get a call for a dozen trucks, but not be told what the person was going to use them for.

Now, states have developed “mission ready packages” that coordinate what they have with what the Guard can share, both with equipment and expertise.

At the same time, Guard units are undergoing a ramp-up in training, especially for large-scale ground combat operations. That has seen at least four combat training center rotations for the Guard in each of the past two years.

And Guard partnerships with active units added to new and increasingly longer deployments to Europe and the Pacific to counter perceived threats from Russia and China.

Which raises the question, will the Guard units be stateside to help when disaster strikes the homeland?

As panel moderator retired Army Lt. Gen. Russel Honoré noted, the largest infantry units in Louisiana and Mississippi were patrolling the dusty roads of Iraq when Katrina hit.