The Earth provides for and protects her children, the Earth Ponies. When they ask for strength, she lends it to them. When they ask for stability, she lends it to them. Sometimes, they ask for things less noble… but the Earth will still lend to them the horrors of earthquakes, molten rock, and toxic plants, if for no other reason then to remind her children what consequences can come from misuse of her power.
 
And, sometimes, the Earth chooses to remind the other creatures dwelling upon her surface what her children are capable of. Those who are violently knocked off of their pedestals are not often eager to climb back up. Those horned and winged ponies best not threaten her children ever again.