Trees can fall during storms for a variety of reasons, including:
Winds: Winds can uproot a tree, with the tree trunk acting as a lever. This is a greater problem for tall trees, because the force that’s applied to the roots and trunk is greater as the tree’s height increases, according to Scientific American. This can also happen if a tree were previously in a more forested area, protected by other trees that have since been cut down (to create a new housing lot, for example).
Rain: When the ground becomes saturated from large amounts of rain, trees can topple more easily. The more wet the ground is, the less wind it will take to make it fall.
There’s no guarantee that, under the right conditions, a tree won’t fall. However, Greg Levine, co-executive director of Trees Atlanta, offered the following tips to help increase the chances your trees will survive a storm:
Check for signs of fungus: Fungus growing on the roots or root flare (where the trunk widens as it transitions to the root system) can weaken the tree, making it more likely to fall in a storm.
Don’t compact tree roots: Parking on tree roots or rolling over them can cause compaction, which weakens the roots and the tree.
Use mulch: Mulch helps create healthy soil and a good environment for "critters" that will promote soil and tree health.
Don't "top" your trees: Cutting main branches back to stubs creates structural issues that can weaken the tree.
Take care when redoing utilities: If you're having a water line replaced or an irrigation system put in or replaced, don't dig a trench near the root system of your trees. This can cause tree roots to be accidentally cut.
Look for multiple trunks: Big trees can develop two trunks that will push against each other, causing cracks that let moisture seep in. This can make the tree rot.
Have trees pruned when needed: Eliminating dead branches helps keep trees healthy.
Consult a certified arborist: If you think a tree is damaged, consult a certified arborist for advice so you can avoid a bigger problem. It's especially important to have trees near your house checked.