You get it from the cave where Team Aqua has taken the submarine to
There is no emerald in the Wayward Cave on T.M 26 which is Earthquake
You cannot buy earthquakes...especially not in emerald. This answer is either fake or very poorly worded.
U go to a lady in a house buy earthquake w/ battle points
Only by Tm
Some Pokemon in Pokemon Emerald that can learn Earthquake through leveling up include Groudon, Swampert, Flygon, and Claydol. There are also TMs available in the game that can teach Earthquake to a wider range of Pokemon.
u find it at the seafloor cavern
salamance didn`t learn earthquake but you can teach it using TM
5, like ruby and sapphire
go to routes 120,111,105 and search for them
you must show the old man the magma symbol
just use dig in the under water trenth
Go to Jagged Pass and go in the middle where the Magma guy was. There is an earthquake and a door appears.