Report on Kick 'em Jenny (Grenada) — 12 December-18 December 2001
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 12 December-18 December 2001
Managing Editor: Gari Mayberry
Please cite this report as:
Global Volcanism Program, 2001. Report on Kick 'em Jenny (Grenada). In: Mayberry, G (ed.), Weekly Volcanic Activity Report, 12 December-18 December 2001. Smithsonian Institution and US Geological Survey.
Kick 'em Jenny
12.3°N, 61.64°W; summit elev. -185 m
All times are local (unless otherwise noted)
The Seismic Research Unit of the University of the West Indies reported that a minor eruption began at Kick-'em-Jenny on 4 December and ended by 8 December. The first signs of unrest occurred in October when a slight increase in seismicity was recorded near the volcano. The eruption began on 4 December when a burst of activity started at 0600, peaking at 1100. Following a short lull, activity again increased and culminated in bursts of T-phase signals (acoustic waves generated from an earthquake or underwater explosion that travel through the ocean). The signals were detected between 1918 and 2231 and were interpreted as explosions associated with a submarine eruption. There was no observed activity on the sea surface. The largest earthquakes associated with the eruption were felt in northern Grenada, ~ 8 km to the S. After 7 December, seismicity returned to background levels. During the eruption the Alert Level was raised from Yellow ("volcano is restless") to Orange ("highly elevated level of seismic and/or fumarolic activity") and returned to Yellow on 8 December.
Geologic Background. Kick 'em Jenny, a historically active submarine volcano 8 km off the N shore of Grenada, rises 1300 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 historical eruptions, mostly documented by acoustic signals, have occurred since 1939, when an eruption cloud rose 275 m above the sea. Prior to the 1939 eruption, which 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. Historical eruptions have modified the morphology of the summit crater.