If a tsunami slammed the Southern California coastline, would we be ready?

California’s Tsunami Preparedness Week, from Monday, March 26 through Friday, March 30, aims to make sure residents and visitors know what to do if a tsunami threatens or hits the coast. Some communities have been holding educational drills all month to prepare for such a scenario.

Tsunamis are mammoth waves caused by underwater activity such as an earthquake. Coastal communities in Southern California started taking the threat seriously a little more than a decade ago, after a massive earthquake in 2004 off the coast of Indonesia triggered a tsunami that left at least 230,000 people dead.

It was soon after that coastal towns here started developing plans to be better prepared in case such a disaster hit — especially after a June 2005 tsunami warning caused mass confusion among residents who didn’t know whether to go or stay.

Among the local municipalities hosting events is Seal Beach, which is holding a Tsunami WalkOut exercise Wednesday, March 28. In Long Beach, a Tsunami Prepardness Walk was held March 17, with a fair that followed. Disaster Preparedness staff this month are visiting residences and businesses in the tsunami inundation, or flood zone, to hand out a preparedness guide designed to teach Long Beach residents how to survive a tsunami

Brad Alexander, public information officer for the California Governor’s Office, said several tsunamis have hit the West Coast over the last five decades. The deadliest one was in the mid-1960s, when a tsunami hit Crescent City, killing 11 people. In that same harbor town in 2011, one man was swept out to sea and boats were damaged after a tsunami battered the coast. Santa Cruz also took a hit.

One thing not to do when a tsunami hits? Don’t go to the coast to see it and put yourself at risk, Alexander said.

“It’s typically not a visual situation,” he said. “You’re not going to see a 500-foot wave, you’re going to have the shoreline receding and minutes or hours later, potentially coming back as either king waves or tall waves. … In a catastrophic situation, you’d have a high tsunami wave. Get to high ground and find shelter.”

California is one of the most prepared states when it comes to disasters, he said. “But there’s always going to be more work.”

Here are some things to know about tsunamis to keep you safe:

1. What is the difference between a “tsunami watch,” “advisory” and “warning”?

A tsunami watch means the danger level is not yet known and that people should stay alert for more information. An advisory means strong currents are likely and that individuals should stay away from the shore. And a warning means an inundating wave is possible and evacuation is suggested.

2. How will we know if we are in danger of a tsunami?

Most Southern California coastal cities have siren systems that would alert residents to seek higher ground during a tsunami warning, as well as street signs and maps on their websites detailing evacuation routes from tsunami inundation areas.

3. How long do we have to evacuate before a tsunami?

If a major earthquake originates in a quake-prone area such as Chile, Alaska or Japan, you may have a few hours to get to safety. But if a quake hits locally, you may only have 15 to 20 minutes.

4. What should you do during a tsunami?

Move to high ground, meaning 100 feet above sea level or two miles inland. If you are on a boat, move to deep water of 600 feet or more. If undocked, you have 10 minutes to either get to shore or head to deeper water. Only head to deep water if your boat is equipped with water, food and shelter, according to the Orange County Emergency Operations Center.

5. Besides moving to safety, what other safety measures should be considered?

Have a family reunification plan so you know you will all be safe. Learn the recommended evacuation routes for the area you live in.

6. What warning signs can we see, hear or feel?

Shaky ground, water receding unusually and a loud ocean roar could mean a tsunami is coming.

7. How can I be prepared?

Assemble a small evacuation kit with essential documents, medications, a flashlight, a portable National Oceanic and Atmospheric Administration weather radio and batteries, water, snacks and warm clothes. Include a silver space blanket in the kit, which can be used to signal a location for air search teams. Keep your evacuation kit by the door so you can grab and go. Also, make reunification plans with your loved ones by deciding when and where to meet if you are separated. Discuss the plan with family, co-workers and neighbors.

8. How can I get an alert?

Go to tsunami.gov to sign up for alerts.

Sources: ready.gov/tsunamis, tsunamizone.org/california, SCNG archives