Kick-'em-Jenny is an active submarine volcano

Submarine volcano

Submarine volcanoes are underwater fissures in the Earth's surface from which magma can erupt. They are estimated to account for 75% of annual magma output. The vast majority are located near areas of tectonic plate movement, known as ocean ridges...

 or seamount

Seamount

A seamount is a mountain rising from the ocean seafloor that does not reach to the water's surface , and thus is not an island. These are typically formed from extinct volcanoes, that rise abruptly and are usually found rising from a seafloor of depth. They are defined by oceanographers as...

 on the Caribbean Sea

Caribbean Sea

The Caribbean Sea is a sea of the Atlantic Ocean located in the tropics of the Western hemisphere. It is bounded by Mexico and Central America to the west and southwest, to the north by the Greater Antilles, and to the east by the Lesser Antilles....

 floor, located 8 km (5 mi) north of the island of Grenada

Grenada

Grenada is an island country and Commonwealth Realm consisting of the island of Grenada and six smaller islands at the southern end of the Grenadines in the southeastern Caribbean Sea...

 and about 8 km (5 mi) west of Ronde Island

Ronde Island

Ronde Island, Grenada is a private island in the Lesser Antilles chain of the Caribbean Sea. The island was listed for sale as of October of 2007 for US$100,000,000, making it currently the most expensive listed island property in the world. Ronde is located approximately 4 miles east of the...

 in the Grenadines

Grenadines

The Grenadines is a Caribbean island chain of over 600 islands in the Windward Islands.-Geographic boundaries:They are divided between the island nations of Saint Vincent and the Grenadines and Grenada. They lie between the islands of Saint Vincent in the north and Grenada in the south. Neither...

. Kick-'em-Jenny rises 1300 m (4,265 ft) above the sea floor on the steep inner western slope of the Lesser Antilles

Lesser Antilles

The Lesser Antilles are a long, partly volcanic island arc in the Western Hemisphere. Most of its islands form the eastern boundary of the Caribbean Sea with the Atlantic Ocean, with the remainder located in the southern Caribbean just north of South America...

 ridge. The South American tectonic plate

South American Plate

The South American Plate is a continental tectonic plate which includes the continent of South America and also a sizeable region of the Atlantic Ocean seabed extending eastward to the Mid-Atlantic Ridge....

 is subducting

Subduction

In geology, subduction is the process that takes place at convergent boundaries by which one tectonic plate moves under another tectonic plate, sinking into the Earth's mantle, as the plates converge. These 3D regions of mantle downwellings are known as "Subduction Zones"...

 the Caribbean tectonic plate

Caribbean Plate

The Caribbean Plate is a mostly oceanic tectonic plate underlying Central America and the Caribbean Sea off the north coast of South America....

 to the east of this ridge and under the Lesser Antilles island arc

Lesser Antilles Volcanic Arc

The Lesser Antilles Volcanic Arc is a volcanic arc that forms the eastern boundary of the Caribbean plate. It is part of a subduction zone, also known as the Lesser Antilles subduction zone, where the oceanic crust of the North American Plate is being subducted under the Caribbean Plate...

.

Activity

The first record of the volcano was in 1939, although it must have erupted many times before that date. On 23-24 July 1939 an eruption broke the sea surface, sending a cloud of steam and debris 275 m (902 ft) into the air and generating a series of tsunami

Tsunami

A tsunami is a series of water waves caused by the displacement of a large volume of a body of water, typically an ocean or a large lake...

s around two metres high when they reached the coastlines of northern Grenada and the southern Grenadines. In 2003, the summit reached 180 m (591 ft) below the sea surface and is thought to have remained constant since the 1960s.

The volcano has erupted on at least twelve occasions since 1939 and 2001 (the last being on December 4, 2001), although none of the eruptions have been as large as the 1939 one and most were only detected seismically. The larger eruptions have also been heard underwater or on land close to the volcano as a deep rumbling sound.

A submersible survey in 2003 detected a crater with active fumarole

Fumarole

A fumarole is an opening in a planet's crust, often in the neighborhood of volcanoes, which emits steam and gases such as carbon dioxide, sulfur dioxide, hydrochloric acid, and hydrogen sulfide. The steam is created when superheated water turns to steam as its pressure drops when it emerges from...

s releasing cold and hot gas bubbles.
Samples of fresh olivine

Olivine

The mineral olivine is a magnesium iron silicate with the formula 2SiO4. It is a common mineral in the Earth's subsurface but weathers quickly on the surface....

 basalt

Basalt

Basalt is a common extrusive volcanic rock. It is usually grey to black and fine-grained due to rapid cooling of lava at the surface of a planet. It may be porphyritic containing larger crystals in a fine matrix, or vesicular, or frothy scoria. Unweathered basalt is black or grey...

were collected. An arc shaped collapse structure appears on the west flank and was the apparent source of a submarine debris avalanche extending 15 km down the ridge slope to the west toward the Grenada Basin.

Etymology

The volcano was unknown before 1939, although "Kick 'em Jenny" appeared on earlier maps as either the name of a small island now called Diamond Rock (or Île Diamante), or the name of the strait between Grenada and Ronde Island (or Île de Ronde). The name itself may be a reference to the waters sometimes being extremely rough.