Tsunami Survival Guide: What It Is and How to Stay Safe

So, what are tsunamis? The National Ocean Service explains that tsunamis are giant waves caused by earthquakes or volcanic eruptions under the sea. This is different from tidal waves that are caused by the gravitational interactions between the Sun, Moon, and Earth.

According to the United States Geological Survey, tsunamis are triggered by several different events. Large earthquakes that occur near or under the ocean are the most common cause. Volcanic eruptions can also create tsunamis, along with submarine landslides where large amounts of underwater rock and soil fall. Even onshore landslides where large volumes of debris fall into the water can trigger these dangerous waves.

The National Ocean Service notes that tsunami waves travel incredibly fast across deep ocean water, moving as fast as jet planes but staying relatively low in height. However, as the waves approach shallow coastal waters, they slow down but build up to much higher and more dangerous heights. These waves act like very fast-moving tides that push inland much farther than regular water, usually coming in a series that can continue for many hours.

Many people wonder if every earthquake near the ocean will create dangerous tsunami waves. The answer might surprise you because not all earthquakes have the power to generate these ocean giants.

According to the United States Geological Survey, earthquake magnitude is just one factor that determines if a tsunami will form. The earthquake must be a shallow marine event that actually moves the seafloor up or down to push the ocean water. Thrust earthquakes, where one part of the earth pushes up over another part, are much more likely to create tsunamis than other types of earthquakes.

The USGS provides clear guidelines about which earthquake sizes can trigger tsunami waves:

- Below magnitude 6.5: Very unlikely to create tsunamis at all. These smaller earthquakes simply do not have enough power to move large amounts of ocean water.

- Magnitude 6.5 to 7.5: Usually do not produce dangerous tsunamis. However, small changes in sea level might happen near the earthquake's center. In rare cases, these medium earthquakes can cause tsunamis through secondary effects like underwater landslides.

- Magnitude 7.6 to 7.8: Might produce destructive tsunamis, especially close to where the earthquake happened. People living far away from the earthquake center might only see small sea level changes, but local areas can face serious danger.

- Magnitude 7.9 and greater: These powerful earthquakes can create destructive tsunamis near their center and cause significant sea level changes and damage across much broader areas. A magnitude 9.0 earthquake can even trigger large aftershock earthquakes of magnitude 7.5 or greater, creating multiple tsunami threats.

Knowing how to react quickly when facing tsunami danger can save your life and the lives of your loved ones. These survival steps are based on advice from emergency experts and people who have survived real tsunami events.

Move to High Ground Immediately

Get to high ground as far inland as possible as soon as you feel a strong earthquake or receive a tsunami warning. Do not wait for official warnings if you live near the coast and feel shaking. Choose high ground that is at least 100 feet above sea level or go at least one mile inland from the shore.

Evacuate on Foot When Possible

Walk or run to safety instead of driving if you can. Roads and bridges might be damaged after an earthquake, and you could get stuck in traffic in a dangerous location. Stay away from damaged buildings and bridges that could fall down.

Follow Evacuation Route Signs

Look for white and blue signs that say "tsunami evacuation route" in coastal areas. These signs have arrows showing the safest direction to go. Follow the signs from one to another until you reach an area marked as safe from tsunamis.

Climb Tall Buildings if Trapped

If you cannot reach high ground in time, go to the third floor or higher in a strong building. Try to get on the roof of the tallest, strongest building you can find. Some coastal areas have special tsunami evacuation towers built for this purpose.

Stay in Your Safe Place for Hours

Remain in your safe location for at least 8 hours after the first tsunami wave. Tsunami activity can continue for many hours, and later waves might be larger than the first ones. Only return to lower areas when emergency officials say it is safe.

Grab Floating Objects if in Water

If you get caught by tsunami water, grab onto something that floats like a tree, door, or life raft. Hold on tightly and try not to swallow the water, which might contain dangerous chemicals and waste.

Head to Deep Water if on a Boat

If you are on a boat when a tsunami warning is issued, steer toward the open ocean facing the waves. Get as far from shore as possible and never return to port during a tsunami warning. If you are already docked, leave your boat and go inland immediately.

An emergency kit, also called a grab-and-go bag, is a collection of important supplies that you can quickly take with you during disasters. Having a ready emergency kit saves precious time when you need to evacuate quickly for tsunamis, earthquakes, floods, or other dangerous situations. This kit should contain everything your family needs to survive for at least three days without help from stores or emergency services.

Water and Food Supplies

- One gallon of water per person per day for at least three days

- Three-day supply of non-perishable food for each family member

- Manual can opener for canned foods

- Paper plates, cups, and plastic eating utensils

- Garbage bags and plastic ties for sanitation

Important Documents and Money

- Copies of important family documents in waterproof container

- Cash and credit cards in small bills

- Emergency contact information for family and friends

- Insurance policies and bank account records

- Identification cards and passports for all family members

Safety and Communication Items

- Battery-powered or hand-crank radio for emergency news

- Flashlight with extra batteries

- First aid kit with basic medical supplies

- Whistle for signaling help

- Cell phone with chargers and backup battery

Personal Care and Clothing

- Complete change of clothing for each person including sturdy shoes

- Warm blankets or sleeping bags for each family member

- Personal hygiene items like toothbrush, soap, and feminine supplies

- Prescription medications for at least one week

- Glasses or contact lenses if needed

Tools and Household Items

- Matches in waterproof container

- Paper and pencil for leaving messages

- Duct tape and plastic sheeting for emergency shelter

- Wrench or pliers to turn off utilities

- Local area maps showing evacuation routes

Remember to check your emergency kit every six months to replace expired food, water, and medications. Store your kit in an easy-to-reach location that all family members know about. Having a well-prepared emergency kit gives you peace of mind and can make the difference between life and death when natural disasters like tsunamis strike without warning.