An active underwater volcano off Grenada's northern coast called Kick 'em Jenny is rumbling and disaster management authorities have been put on alert.

Since its discovery in 1939, Kick 'em Jenny has erupted at least 12 times, most recently in 2001. It hasn't caused any deaths or injuries.

On Thursday, the Seismic Research Center at the University of the West Indies said seismic activity has increased at the submerged volcano, which rises above the seafloor 8 kilometers (5 miles) north of Grenada.

Divers also reported seeing some "degassing" on the seafloor off Grenada as bubbles of gas-rich magma burst.

Center researchers have put an alert level at "orange," which means an eruption could take place within 24 hours.

Jenny is one of about 100 known underwater volcanoes in the world.