From Wikipedia, for what that's worth......
It would seem the hardy hole would have to be centered to get a good vertical launch, which they aren't usually, and plugged on one end, which they usually aren't. But, it's Wikipedia and who knows.
Base to base only gets a few feet high because the force goes out to the sides as well.
"Typically, two anvils are used: one as a base (placed upside down), and another one (also known as the "flier") as the projectile (placed right-side up, atop the base).[2] An alternative method is to place the bottom anvil upright, and fill the hardy hole with black powder. A torus or washer, often made from a playing card, is placed over the hole, with a space for a fuse or powder trail. The top anvil is placed upside down, face to face with the bottom anvil.[3]
A technique for firing a single anvil uses a stone base. The space formed by the anvil's concave base is filled with black powder. Modern double-base powders have much higher energy densities, making them unsuitable. A fuse is made to project out, then lit, and the resulting deflagration sends the projectile anvil several feet into the air.
Anvils were traditionally fired on St. Clement's Day, honoring Pope Clement I, the patron saint of blacksmiths and metalworkers.[4]
Although its practice has lessened in recent years[citation needed], enthusiasts still participate in anvil launching events and competitions. On September 5, 2011, The Science Channel premiered Flying Anvils, a reality television series about anvil firing."