Seismic stations... began to record very strong acoustic (T-phase) signals, probably associated with an eruption of the... Kick-'em-Jenny... on 26 March at 1112. Overflights of the area during the period of vigorous seismicity did not reveal any water discoloration or other surface changes above the volcano, which had a summit depth of about 160 m in 1982.

Thirteen distinct seismic bursts, lasting up to 19 minutes, were recorded 26-27 March on instruments operated by the Seismic Research Unit, Univ of the West Indies. The IPGP's Mt. Pelée seismic network on Martinique, 250 km NNE of Kick-'em-Jenny, recorded strong T-waves on 26 March at 1117:22, 1502:30, 1723, and 2034 (the latter felt by residents of NW Martinique), and on 27 March at 0035:40 and 0424:25. T-waves reached IPGP's Soufrière de Guadeloupe net, 450 km N of Kick-'em-Jenny, on 26 March at 1118. The initial activity saturated the Grenada seismograph and the largest burst of seismicity, at about 1721 on 26 March, was felt on northern Grenada. After a single 14-minute episode that started at 0103 on 28 March, seismicity stopped on all but the Grenada instrument, which continued to record occasional low-frequency (0.5-2 Hz) signals for periods of about 30 seconds to more than 3 hours. The latest reported low-frequency episode occurred on 5 April between about 0500 and 0800.

Geological Summary. Kick 'em Jenny, an active submarine volcano 8 km off the N shore of Grenada, rises 1,300 m from the sea floor. Recent bathymetric surveys have shown evidence for a major arcuate collapse structure, which was the source of a submarine debris avalanche that traveled more than 15 km W. Bathymetry also revealed another submarine cone to the SE, Kick 'em Jack, and submarine lava domes to its S. These and subaerial tuff rings and lava flows at Ile de Caille and other nearby islands may represent a single large volcanic complex. Numerous eruptions have occurred since 1939, mostly documented by acoustic signals. Prior to the 1939 eruption, when an eruption cloud rose 275 m above the ocean and was witnessed by a large number of people in northern Grenada, there had been no written mention of the volcano. Eruptions have involved both explosive activity and the quiet extrusion of lava flows and lava domes in the summit crater; deep rumbling noises have sometimes been heard onshore. Recent eruptions have modified the morphology of the summit crater.

Information Contacts: W. Ambeh, K. Rowley, L. Lynch, and L. Pollard, UWI; A. Redhead, Office of the Prime Minister, Grenada; J.P. Viode and G. Boudon, Observatoire Volcanologique de la Montagne Pelée, Martinique; C. Antenor and M. Feuillard, Observatoire de la Soufrière, Guadeloupe; J.L. Cheminée, N. Girardin, and A. Hirn, IPGP Observatoires Volcanologiques, France.