On Pokemon Diamond where is the TM earthquake?

Answer 1

First, head to Eterna City. Then, go to the southernmost part of the city, where the exit is. This'll lead you to a cycling road (Route 206); head all the way down and exit the cycling road. You'll still be on Route 206, so go right until you see a tree that can be cut by HM01:CUT. Cut it down, and then head along the grass, going north. You'll eventually see a cave entrance (WAYWARD CAVE.) Once inside, you'll need to rock smash your way through the caves maze and find ramps that you can hop over with the bike.