Volcano activity on moon
The grey areas are known as "maria" (singular:"mare") and they were formed from flood  basalts. These are a type of volcano and they have formed on earth too, examples include the lake eruption on Iceland, and the Deccan traps, that played a role in the mass extinction 65 million years ago. 

On the moon, the flood basalt is old. About 3-4 billion years old, with some regions probably younger, but nothing less than 1 billion. Volcanism is driven by the heat of radioactive decay. On the moon there are no longer enough radioactive elements to melt rock, and so the moon is no longer a volcanic active body. 

There are no active volcanoes on the moon, and there is no prospect of any in the future.