Trees and quakes

[atree]

Hey folks

 

Just had a major earthquake here (if you didnt already know) and there has only been 1 or 2 uprooted trees due to the quake.

 

How come tree roots manage to withstand an earthquake without breaking up??

 

Thanks

[RobRainford]

i would think that due to the trees having anchor roots and that an earthquake gives them a good shake i would assume that its not much more stress than a strong wind?

[b101uk]

It’s a bit different to wind, wind blows and pushes the top of the tree sideways which is the main force trying to uplift one side of the root plate.

 

i.e. in a wind the top of the tree moves yet to bottom stays stationery, in an earthquake the top of the tree stays more stationery and the bottom of the tree moves lots more.

 

Also in wind there is a force trying to pull half the roots up, in an earthquake there is little force trying to pull up as the main force is trying to pull horizontally (it is easer to snap wood/roots by bending it rather than just pulling either end of it) also roots will pull an amount threw the soil horizontally without much damage due to very local ground movements and small shears/cracks

 

As an e.g. Try holding a plant in a pot and shaking it vs. it in a strong wind