Tornadoes are one of nature’s most violent and destructive forces. An EF5 tornado, the strongest on the Enhanced Fujita scale, packs winds over 200 mph and can completely level well-built homes and throw vehicles hundreds of yards. When an EF5 tornado is bearing down, surviving its wrath may seem impossible. However, taking shelter in an underground basement or storm cellar can greatly improve your odds of making it through alive.
What is an EF5 tornado?
The Enhanced Fujita scale rates tornadoes from 0 to 5 based on the damage caused. EF5 is the highest category, reserved for the most violent and destructive tornadoes. To get an EF5 rating, a tornado must have winds over 200 mph – strong enough to sweep away sturdy, well-built homes. Concrete foundations may be swept clean and vehicles can be thrown up to half a mile away. EF5 tornadoes can also snap large trees and throw railroad cars through the air like toys. Some EF5s have winds approaching 300 mph.
EF5 tornadoes are exceptionally rare. Since ratings began in the 1950s, only a handful of tornadoes have received an EF5 rating. Some well-known EF5s include:
- The 1999 Bridge Creek–Moore tornado that struck Oklahoma City
- The 2011 Joplin tornado that devastated Joplin, Missouri
- The 2013 El Reno tornado that took experienced storm chasers by surprise in Oklahoma
Many EF5s have winds strong enough to sweep foundations clean and debark trees. They can leave behind streaks of bare earth through grasslands. Most other structures in their path will be completely demolished.
Why basements offer safety
Against the incredible ferocity of an EF5 tornado, no location above ground can be considered safe. However, a sturdy, well-built basement or storm cellar offers one of the best shots at surviving. Here are some key reasons basements provide good protection:
- They place more physical structure between you and extreme winds. The deeper underground you go, the more earth and concrete helps buffer you against violent winds.
- They provide shelter if your home collapses. Even sturdy homes can be demolished by an EF5. A basement preserves an underground space to take refuge in if your home is obliterated.
- They offer protection against flying debris. Basements keep you away from the many dangerous projectiles swirling around in an EF5’s winds.
However, not all basements are created equal when it comes to tornado safety. Having a properly constructed and well-supplied storm shelter or “safe room” in your basement provides the very best odds of surviving an EF5.
Building a Safe Basement Storm Shelter
To turn your basement into a reliable storm shelter against an EF5 tornado, FEMA recommends following these guidelines:
- The shelter should be built partially below ground in your basement, preferably in the corner farthest from exterior doors and windows.
- Reinforce the walls, ceiling, and door with steel and concrete to withstand extreme winds and impacts from flying debris.
- The door should be heavy steel or concrete and open outwards so debris doesn’t prevent it from opening.
- Include ventilation openings to prevent dangerous gasses from accumulating.
- Stock the shelter with critical emergency supplies like water, non-perishable food, flashlights, first aid kit, tools, and battery-powered radio.
Properly constructing a dedicated safe room following building codes and FEMA guidelines can be expensive. However, it offers near-absolute protection even against the strongest conceivable tornadoes. If building a custom safe room in your basement isn’t feasible, the next safest options are:
- A small interior room or closet with no windows on the lowest floor of your basement.
- A corner of your basement farthest from windows and doors, ideally under a sturdy workbench or mattress for overhead protection.
Necessary basement features
Not all basements are sturdy enough to survive an EF5 tornado. Here are some key features your basement requires to provide adequate safety:
- Poured concrete or concrete block walls. Wood or cinderblock basement walls can easily fail in an EF5’s extreme winds.
- Small window area. More windows mean more opportunities for breaches from flying debris and increased wind damage.
- Low ceiling with thick floor joists. This supports the upper levels against collapse.
- No openings or penetrations between upper floors and basement. Open staircases can funnel wind and debris into your basement space.
Also avoid basements with large garage door-style openings to the outside. The door could fail and expose the interior to the tornado’s full force.
Taking refuge during the tornado
Once inside your sturdy basement shelter or safe room, here are some tips to maximize safety when the tornado strikes:
- Get under a heavy table, workbench, mattress or other cover if possible.
- Wear a helmet or other head protection if you have it.
- Cover yourself with blankets, sleeping bags, mattresses and cushions.
- Remain in the shelter until you receive an all-clear notice or are certain the storm has passed.
- Have a way to get emergency notices. A weather radio, mobile phone alerts or AM/FM radio can keep you informed.
Avoid taking refuge in corners, under staircases and next to exterior walls, as these areas are more vulnerable to collapse and flying debris damage.
After the storm passes
Once the roar of the winds and rumbling subside, don’t immediately open the door and emerge after an EF5 passes over. Here are some precautions to take before exiting:
- Wait at least 15-30 minutes to allow any lingering winds and debris to settle.
- Listen for any indication the upper floor has collapsed or the area outside your shelter is compromised.
- Check a battery-powered radio or mobile device for emergency notices and an all-clear signal before emerging.
- Watch for downed power lines, damaged gas lines, debris, and other hazards outside before exiting the basement.
Have an emergency plan to reconnect with family members and evacuate to a designated meeting place or shelter if your home is heavily damaged.
Conclusion
EF5 tornadoes are nature’s most powerful and destructive storms. With winds over 200 mph, no home or ordinary building can guarantee safety in the direct path of an EF5. However, a properly constructed basement storm shelter offers one of the best chances of surviving through the storm. By selecting a corner or interior room of your basement farthest from windows, reinforcing the walls and ceiling, and following safety precautions during the storm, you can dramatically increase your odds of making through even an extremely violent EF5 tornado.