Seismic activity at underwater volcano Kick 'em Jenny near Grenada, Eastern Caribbean is decreasing, the Seismic Research Center (SRC) of the University of the West Indies reported on July 25.
Increased activity at the volcano started on July 11, 2015 and was followed by strong and continuous seismic signals recorded from 05:25 to 07:00 UTC on July 23 which prompted authorities to raise the alert level to Orange.
Video published on July 23, 2015.
Following the hour long eruption signal which started at 05:42 UTC on July 23 activity continued at an elevated level until 17:30 UTC, with more than 400 recorded events. The largest of these was of M3.3.
At about 06:00 UTC on July 24 an explosion signal was recorded and lasted for about an hour. T-phase from this event was recorded in Montserrat confirming the nature of the activity. The number of earthquakes declined during the day, with only 89 events recorded up to 20:00 UTC.
Overnight (July 24 - 25) this decline continued and between 20:00 UTC on July 24 to 10:30 UTC on July 25 less than 20 earthquakes were detected.
A reconnaissance flight was conducted during the afternoon of July 25 with, volcanologist Dr. Frederic Dondin, one of two of the UWI-SRC team currently in Grenada. Nothing out of the ordinary was observed at the surface above the volcano.
Additional instruments were also placed closer to the volcano which reduces the threshold magnitude of events associated with the Kick-‘em-Jenny system that can be identified.
The current alert level remains at Orange, SRC said. It should be noted that this alert level system relates specifically to the Kick ‘em Jenny submarine volcano. It serves to guide local authorities and residents in Grenada and the surrounding Grenadine islands on what is appropriate at this level of activity.
Mariners are therefore encouraged to observe the Exclusion Zone and not enter within a 5 km (3.1 miles) radius of the Kick ‘em Jenny crater.
Kick 'em Jenny, a historically active submarine volcano 8 km (5 miles) off the north shore of Grenada, rises 1 300 m (0.8 miles) from the sea floor. Recent bathymetric surveys have shown evidence for a major arcuate collapse structure that was the source of a submarine debris avalanche that traveled more than 15 km (9.3 miles) to the west.
Bathymetry also revealed another submarine cone to the SE, Kick 'em Jack, and submarine lava domes to its south. 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 at Kick 'em Jenny since 1939, when an eruption cloud rose 275 m (0.17 miles) above the sea surface. Prior to the 1939 eruption, which was witnessed by a large number of people in northern Grenada, there had been no written mention of Kick 'em Jenny. 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. (GVP)
NATIONAL DISASTER MANAGEMENT AGENCY (NaDMA) Grenada (July 26, 2015) - The Seismic Research Centre (SRC), University of the West Indies has reported that the activity levels at the Kick-‘em-Jenny under water Volcano has reduced significantly during the last 48 hours. Since 10:00 UTC (18:00 local time), on Saturday, July 25, no activity was recorded.
On Saturday, July 25th at around 09:50 UTC (17:50 local time), a team including a Volcanologist from the SRC, Grenada’s Acting National Disaster Coordinator, and a camera person, participated in a fly over of the Kick-‘em-Jenny area by helicopter. The volcanologist, Dr. Frederic Dondin, who has conducted extensive research on Kick-‘em-Jenny, concluded, after his observations, that there was absolutely nothing unusual in the area.
Based on the above findings, and given the fact that the activity levels at Kick-‘em- Jenny has diminished, the Government of Grenada, based on the advice of the SRC has lowered the alert level to YELLOW with immediate effect.
The YELLOW alert level means that vessels should observe a 1.5 km exclusion zone.
However, as a precautionary measure, the marine community is advised to continue observing the 5 km exclusion zone.