If you look closely at the top of the tree you can see that this palm leaf had some "help" other than wind in coming down. Comparing the size of the man with the size of the leaf will give you a feel for how large these fronds are. When the fronds blow down they usually come down one at a time, but occasionally a group of fronds will become dislodged all at once. You can see that it doesn't take many palm fronds to make a good sized pile.
These fronds are pulled from yards and the middle of the roads, wherever they fall, and stacked by the curbs. The city brings trucks around to gather them up. Southern California cities don't have snow removal problems, but they do have to keep up with the palm fronds. (Thanks to Elder Puskas for the photographs.)