YEAH, HE PROBABLY IS: Elon Musk may actually be serious about tunneling under L.A.

Billionaire innovator Elon Musk declared early Wednesday that he’s ready to move ahead with his recently formulated ambitions to bore holes, possibly under the city.

“Exciting progress on the tunnel front,” Musk tweeted. “Plan to start digging in a month or so.”

Digging just where and how, no one knows. Coming from anyone else, such a declaration might brushed off as a joke.

But given that Musk is the entrepreneur who, with a team, reshaped mobile payments (PayPal), sent rockets into space (Space Exploration Technologies, or SpaceX) and launched an electric-car company (Tesla Motors), the tweets are unlikely to be dismissed. He is, after all, being taken seriously about a possible Mars mission.

Whatever you might think of the merits of Musk’s various projects, he thinks big and he writes big checks.