'Kick 'em Jenny' is an underwater volcano 8km off the northern coast of the island of Grenada in the Caribbean. She¹ has erupted at least 10 times since discovery in 1939 and has provided scientists with a rare opportunity to learn about the growth and gradual development of submarine volcanoes into islands.

The name Kick 'em Jenny is probably a reference to the force with which she erupted in 1939. Then, sizeable rocks were thrown as high as 300m above the surface of the sea.

Where is Kick 'em Jenny?

Kick 'em Jenny is part of a chain of volcanoes known as the Lesser Antilles volcanic arc. This arc is associated with a subduction zone at the eastern boundary of the Caribbean Plate. Kick 'em Jenny is the southern-most active volcano in this arc, and is also the only active submarine volcano there.

In relation to the Lesser Antilles archipelago, the volcano is located near its southern extent² - Grenada being the southern-most island in the chain.

How Deep is Kick 'em Jenny?

The summit of Kick 'em Jenny lies 180-190m below sea level³ in the 1960s and 70s. In the late 1970s and early 1980s she was measured to be as little as 150m below sea level. This was due to the growth of a dome within the volcano's crater. This dome collapsed significantly in eruptions in the late 1980s. Surveys carried out in March 2002 have shown the dome to be 180m below sea level.

These surveys also discovered an additional three craters and two domes in the region. One of these craters was named Kick 'em Jack!

Is Kick 'em Jenny a Threat?

Kick 'em Jenny is located 4.5km from any land⁴ and as such would pose only two main dangers: threats to shipping, and tsunamis.

• Shipping Threats:
  This is of more immediate concern as it is present even if the volcano does not erupt. During an eruption, rough seas and ejected debris would cause damage to any vessels in the vicinity. However, in 'calm' times, the volcano can still emit considerable amounts of volcanic gas⁵. This gas appears as bubbles within the water. A high concentration of these bubbles would result in a reduction of water density. This reduced water density would cause ships to lose buoyancy and could even result in them sinking. For this reason, there is a permanent exclusion zone⁶ extending 1.5km (in all directions) from the summit of Kick 'em Jenny. This exclusion zone is increased to 5km during eruptions.

• Tsunamis:
  Until the most recent surveys, it was thought that Kick 'em Jenny was growing taller with each eruption. This would have meant that eventually she would have reached close enough to the surface to trigger destructive tsunamis⁷ and that eventually a new Caribbean island would have emerged. However, since the discovery that the dome suffered a major collapse in the 1980s, tsunamis are not seen as an immediate threat - any tsunamis generated under these conditions would dissipate quickly.

So, in its current condition, Kick 'em Jenny is not considered to be an immediate threat.