Volcanoes

A volcano is a naturally occuring opening in the surface of the Earth through which molten, gaseous, and solid material is ejected. A volcano is also the mountain created by the deposit and buildup of materials ejected from a vent in a central crater.

Grenada has two active volcanoes namely Kick 'Em Jenny and Mt. St. Catherine. Kick-'em-Jenny (also: Kick'em Jenny or Mt. Kick-'Em-Jenny) is an active submarine volcano on the Caribbean Sea floor located 8 km north of the island of Grenada and about 8 km west of Ronde Island in the Grenadines. Kick-'em-Jenny rises 1,300 meters (4,300 feet) above the sea floor on the steep inner western slope of the Lesser Antilles ridge. The North American tectonic plate is subducting the Caribbean tectonic plate to the east of this ridge and under the Lesser Antilles island arc. 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 into the air and generating a series of tsunamis around two metres high when they reached the coastlines of northern Grenada and the southern Grenadines. In 2003, the summit reached 180 m 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 fumaroles releasing cold and hot gas bubbles. Samples of fresh olivine basalt 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.

The island of Grenada is composed of five Pliocene-to-Pleistocene volcanic centers, the youngest and highest of which is Mount St. Catherine on the northern end of the island. A complex of lava domes is located within a horseshoe-shaped crater breached to the east at the summit of 840-m-high Mount St. Catherine. Pyroclastic-flow deposits extend to the NW from the extensively weathered volcano. The most recent activity on Grenada originated from a group of young maars, tuff rings, and scoria cones that extend SSW-NNE across the length of the 30-km-long island. No eruptions of St. Catherine are known in historical time, although the most recent eruption along a NE-SW-trending fault cutting across the island produced a scoria cone near Radix village that could be less than 1000 years old. Hot springs and fumaroles are present at several locations on Mount St. Catherine.