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Subsea Volcanic Activity: Kick ’em Jenny – Submarine Volcano, Caribbean Sea


Natural Hazard – Volcanic Activity

North Atlantic  – Caribbean Region | West Indies and Vicinity, Kick ’em Jenny Submarine Volcano
Location:  12°18’00.0″N 61°38’24.0″W, 8 km (5 mi) north of the island of Grenada
Submarine volcanoSummit Depth | -185 m (-607 ft) 
Current status: Caution

Live Seismic Data from BBGH – Gun Hill, Barbados (Data updates automatically every 30 minutes.)

Volcano Activity in Grenada

Kick em’ Jenny Volcano Exclusion Zone

Exclusion Zones at Kick ’em Jenny. The volcano is located at 12.18 degrees North and 61.38 degrees West. The first exclusion zone (1.5km) is always in effect. The second exclusion zone is usually enforced during an eruption (5km). Image: The University of the West Indies Seismic Research Centre. All rights reserved.

Saturday, 25 July, 2015 at 08:46 UTC

An active underwater volcano is rumbling beneath the Caribbean Sea. And scientists say an eruption could sink water vessels and shoot up hot rocks into the air. The volcano, Kick ’em Jenny, sits off the northern coast of Grenada. Officials raised its threat level Thursday to orange, which means it could erupt with less than 24-hour notice. Kick ’em Jenny started stirring on July 11, and has produced more than 200 small earthquakes since then, according to the Seismic Research Centre at the University of the West Indies. Even though the crater is about 600 feet (180 meters) below the surface of the ocean, the volcano poses hazards to locals and water vessels in the region.To clear its path and reduce risks, scientists set up an exclusion zone for shipping vessels around the volcano. Recreational vessels must stay at least 5 kilometers (3 miles) away from the summit of the volcano. If it erupts, Kick ’em Jenny could displace seawater and produce a tsunami, though the risks of that are relatively low, scientists say. If an eruption causes a tsunami, it is likely to be smal l and confined to nearby islands. But other risks to shipping and marine vessels in the region are especially significant. Underwater or submarine volcanoes release intense amounts of gas into the sea during eruptions — and at times in between eruptions during a process called degassing. Such gas bubbles lower water density and can cause ships to lose buoyancy and sink. In addition to putting water vessels at risk of sudden sinking, an eruption could throw hot rocks, known as ballistic projectiles, up through the water and into the air far above the ocean surface. Such rocks can go up to 3 miles (5 kilometers) from the volcano and have the ability to significantly damage or destroy ships. One of Grenada’s worst maritime disasters is believed to have occurred as a result of degassing from the Kick ’em Jenny volcano in 1944. At least 60 people died when a ship sank with 60 people on board.

Friday, 24 July, 2015 at 02:57 UTC

An increase in seismic activities at the submarine volcano Kick ’em Jenny on Thursday morning, has prompted the National Emergency Council to meet with a team from the University of the West Indies(UWI) seismic unit in Trinidad and Tobago. We were informed through the official channel about the increase activities at Kick ’em Jenny and like we did early we again call on all marine interest to observe the no exclusion zone of five kilometres around the summit of the volcano,” said Coordinator of the National Disaster Management Agency, Terrence Walters. He promised that a detailed statement will be issued following the meeting. On Thursday, the UWI seismic unit posted an advisory informing the public that it has change the alert level of the volcano from yellow to orange stating that at 3:00am (local time), a strong continuous signal was observed on instruments monitoring the submarine volcano. “Signs of elevated seismicity (earthquakes) began on 11th July and continue to present,” said the advisory which explained that for the period since the 11th July a total of more than 200 micro and small earthquakes, of varying magnitudes, have been recorded, with the largest, prior to the strong signal, less than magnitude 3.0.” “There have also been observations from divers of degassing occurring off the west coast of Grenada in the Moliniere Sculpture Park area. This activity is being closely monitored by The UWI-SRC and further updates would be issued as more information becomes available,” the advisory also said. An alert orange mean highly elevated level of seismic activity or other unusual activity. This means that an eruption may begin with less than twenty-four hours notice. The seismic unit says all regional governments will be alerted through Disaster Coordinators . The release stated that local radio stations in Grenada, St. Vincent and the Grenadines, Barbados and Trinidad have been placed on alert. In addition, all shipping are required to stay outside the first exculsion zone that is 1.5km from the summit and non-essential shipping such as pleasure craft should stay 5km clear of the summit. Since the rumbling at Kick ’em Jenny telecommunications service in Grenada has being affected with only the FLOW network apparently operating.

Friday, 24 July, 2015 at 02:36 UTC

Potential Kick ’em Jenny Activity (Orange Alert) and the Associated Tsunami Threat Statement from the Pacific Tsunami Warning Center and US National Tsunami Warning Center

Kick ’em Jenny is an active submarine volcano or seamount on the Caribbean Sea floor, located 8 km (5 mi) north of the island of Grenada and about 8 km (5 mi) west of Ronde Island in the Grenadines at roughly 12.30° N, 61.64° W. Its summit is approximately 200 m (600 ft) below the surface of the ocean.


The Seismic Research Centre (SRC) of the University of the West Indies has issued an Orange Alert for the underwater volcano Kick ’em Jenny1. An Orange Alert means “Highly elevated level of seismic and/or fumarolic activity or other unusual activity. Eruption may begin with less than twenty-four hours notice.”


Instruments monitored by SRC recorded strong, continuous seismic activity from the volcano between 1:25 am and 3:00 am, local time, July 23, 2015 suggesting than an eruption could occur with less than 24-hours notice. Signs of elevated seismicity (earthquakes) began on July 11th and continue to the present.

What is the tsunami threat?

An undersea volcanic eruption can displace the overlying seawater, generating tsunami waves. The amplitude of the waves and area threatened depends upon many factors including the size, depth, and nature of the eruption. Should a tsunami occur, waves would reach Grenada within just a few minutes. If the tsunami were large enough to expand further, it would reach St. Vincent within 10 minutes, Martinique and Tobago within about 30 minutes, and Barbados within about 40 minutes. A very large tsunami could reach the northern coast of Venezuela to the south and the Leeward Islands and Puerto Rico within an hour and a half. Any tsunami hazard would be confined to the Caribbean region.

What is being done?

Kick ’em Jenny activity is being closely monitored by the SRC and further updates will be issued by SRC as more information becomes available. The Pacific Tsunami Warning Center and US National Tsunami Warning Center are also following the situation closely and will be monitoring seismic and sea level data from the nearest seismic and coastal sea level gauges. Should an eruption be confirmed and/or tsunami be detected they will issue appropriate messages to their respective areas of responsibility in the Caribbean region.

Citizens are reminded to follow all instructions from their local emergency management. Some rules for tsunami safety and response can be found at:

SRC recommends that vulnerable communities be advised of evacuation routes and transport be put on standby. SRC indicates that local radio stations in Grenada, St. Vincent, Barbados and Trinidad have been placed on alert. SRC recommends that the public listen to their local radio continuously for updates and visits the Seismic Research Center website if possible. SRC instructs that shipping vessels should stay outside of the first exclusion zone – 1.5 km from the summit of Kick ’em Jenny and that non-essential shipping, such as pleasure craft, should stay outside of the secondary exclusion zone – 5 km clear of the summit

Thursday, 23 July, 2015 at 17:34 (05:34 PM) UTC.

The alert level on the Kick ’em Jenny underwater volcano has been elevated to orange. This means there are highly elevated levels of seismic and/or venting activity and eruption may begin with less than twenty-four hours’ notice. Alert levels go from green to yellow, orange and then red. According to the Seismic Research Centre (SRC) of the University of the West Indies, this is due to increased seismic activity in the area since July 11. Since that day, more than 200 micro and small earthquakes of varying magnitudes have been recorded. Click here to see what the different Alert Levels mean. Today, from 1:25 a.m. to 3 a.m., a strong continuous signal was observed on instruments monitoring Kick ’em Jenny. Divers off the west coast of Grenada have also observed degassing in the Moliniere Sculpture Park area. The SRC also advises that the alert level system is primarily for Grenada. Currently, the volcano is most dangerous for ships and boats since the gases released by Kick ’em Jenny can lower the density of the water causing them to sink even if it is not erupting. For this reason there is an exclusion zone around the summit of the Kick ’em Jenny. SRC says it will continue to monitor the activity, and update as more information becomes available.


Geological Summary:

Kick ’em Jenny, a historically active submarine volcano 8 km off the north shore of Grenada, rises 1300 m 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 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 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.


Monitored and quiet; multi-beam finds craters and domes

The University of West Indies Seismic Research Unit (SRU) has augmented their instrumental monitoring network and warning system at Kick ’em Jenny submarine volcano. In addition to long-period and broadband seismometers to sense earthquakes, they have also employed tide gauges to measure seawater disturbances, hydrophones to discern submarine explosions, and tilt meters and global positioning system (GPS) stations to detect long-term ground deformation. The instruments may disclose anomalies and critical symptoms before an eruption begins. Various combinations of these instruments were installed at Mt. St. Catherine, Sauteurs, The Sisters Rocks, Isle de Ronde, Isle de Caille, and Carriacou (figure 4).

Figure 4. A map indicating positions of monitoring instruments for the current network at Kick ’em Jenny. Tilt meters and tide gauges were not functioning at the time of this writing (early 2005). (Inset) Grenada and Carriacou islands lie at the S end of the West Indies. Courtesy of SRU.

The NSF Caribbean Tsunami Workshop was held in March 2004 (Mercado-Irizarry and Liu, 2004). The Workshop’s program ended its Introduction section with this statement: ” . . . Kick ’em Jenny, close to the islands of the southeastern Caribbean (just 10 km N of Grenada), is of much concern to the local governments. Past eruptions during the last century (1939, 1965) resulted in observed deep water tsunamis, with the one in 1939 being measured as 1 m high [Shepherd, 2001]. The concern is such that, for the first time (at least in the region), a banking institution (the Caribbean Development Bank) is funding a monitoring program [at] the volcano.”

A 29 December 2004 article entitled “Tsunami warning system for the Caribbean,” posted on the SRU website, also addressed the issue. It noted that, “The devastation caused by the tsunami which ravaged several Asian countries on 26th December 2004 has sparked discussion on the importance of a tsunami early warning system in the Caribbean. While in theory such a system may seem invaluable in light of the Asian disaster, scientists at the Seismic Research Unit currently believe that several factors should be seriously considered before assuming that a tsunami early warning system would be beneficial to the region. Head of the Seismic Research Unit, Dr. Richard Robertson, says that ‘Before the region spends valuable resources on setting up new instruments for a tsunami early warning system, we need to strengthen our existing networks and focus on improving public education and communication activities with regard to geologic hazards in the region.'”

Gas release, T-phase seismicity, and minor eruption clouds. The question of whether or not there is strong fumarolic activity in the crater has been a source of speculation for a number of years. It has been suggested that warmed water rising in convection currents contributed to the reputation of the Kick ’em Jenny region for rough water. The emission of large quantities of bubbles was observed in 1989 when the submersible Johnson Sealink entered the crater a few months after the 1988 eruption (SEAN 14:05).

A water column containing a significant proportion of rising gas bubbles results in a local lowering of the seawater’s density. (The rising bubbles displace some of the sea water, and at or near the sea surface they provide negligible support to the ship, thus resulting in a loss of buoyancy for ships passing over the volcano.) To account for this hazard, and the risk posed by ejecta, an exclusion zone 1.5 km in radius was created over the volcano (Shepherd, 2004).

At least 11 historical episodes of hydro-acoustic (T phase) signals have been detected since 1939 when an eruption cloud rose 275 m above the sea surface (Shepherd and Robson, 1967, Smith and Shepherd, 1995, Lindsay et al., 2005). Material was also ejected during the 1974 eruption, and the 1988 eruption was associated with turbulent discolored water (Lindsay and others, 2005). Some of these were described in Smithsonian reports dating back to 1977.

Regarding T-Phase waves. A short-period wave group from a seismic source that has propagated in part through the ocean is called T-phase or T(ertiary)-wave (Linehan, 1940; Tolstoy and Ewing, 1950; Walker and Hammond, 1998). The wave group propagates with low attenuation as hydro-acoustic (compressional) waves in the ocean, constrained within a low sound-speed wave guide (the sound fixing and ranging-SOFAR-channel) formed by the sound-speed structure in the ocean. The T-phase signal may be picked up by hydrophones in the ocean or by land seismometers. Upon incidence with the continental shelf/slope, the wave group is transformed into ordinary seismic waves that arrive considerably later than seismic wave groups from the same source that propagated entirely through the solid Earth.

2002 and 2003 Surveys. A 2003 oceanographic survey of Kick ’em Jenny was conducted jointly by the National Oceanic and Atmospheric Agency (NOAA), SRU, and the University of Rhode Island (URI) using the NOAA Research VesselRonald H. Brown. This survey supplemented data obtained previously from a cruise passing the volcano on 12 March 2002 (BGVN 27:06). That effort produced the bathymetric image … reproduced here as figure 5 (BGVN 27:06). The arcuate scarp on the image suggested that the volcano was once the scene of sector collapse. The inferred submarine debris avalanche has an estimated total volume of ~ 10 km3, and a maximum runout distance of at least 15 km (Sigurdsson and others, 2004; Shepherd 2004). The collapse clearly occurred prior to the growth of the small central edifice at Kick ’em Jenny. The ages of these various features remain unknown.

Figure 5. Morphology of Kick ’em Jenny, as revealed by a multi-beam survey by the NOAA Research Vessel Ronald H. Brown in March 2002 (N is toward the top; for approximate scale, the sub-circular summit crater is about ~ 300 m in diameter). The survey showed that the volcano’s smaller, modern, active cone sits nested within a larger U-shaped depression that wraps completely around the cone’s E side and opens toward the W. This larger depression presumably formed by slope failure and generated a W-directed debris avalanche that appears to lie within a marginal, confining levee. Courtesy of NOAA.

Figures 6 and 7 highlight the discovery of other volcanic features on the sea floor just E of Kick ’em Jenny. Little is known about them aside from their basic morphology illuminated by the 2003 survey. Discoveries near Kick ’em Jenny included three craters (C1, C2, and the largest, Kick ’em Jack) and two domes (D1 and D2). The mutual relations and ages of these newly recognized features remain uncertain.

Figure 6. Vertically exaggerated SeaBeam image of Kick ’em Jenny and newly identified craters and domes discovered in March 2003. Kick ’em Jenny’s summit occurs adjacent to the crater rim at a depth of ~ 185 m. The deepest point on Kick ’em Jenny’s crater floor lies at ~264 m depth. The summit sits at 12°18.024’N, 61°38.388’W (12.3004°N, 61.6398°W). The image’s left side is drawn N-S (i.e. N towards the upper left). Tick marks along the margins are at 0.01 degree intervals, a spacing equivalent to 1.8-1.9 km. The distance between Kick ’em Jenny and Kick ’em Jack is about 4 km. A vertical scale at the left indicates water depth: 0, -250, -500, and -750 m. Courtesy of NOAA and SRU.
Figure 7. Broad-scale SeaBeam image of Kick ’em Jenny and adjacent features compiled from Ronald H. Brown cruise observations, March 2003. North is up. The crater rim of Kick ’em Jenny (“rim”), as well as the rest of the body of that dome, lie within a larger arcuate scarp that wraps around the dome’s E side. On the dome’s W side the scarp extends outward, crossing a swath of sea floor as two sub-parallel arms (indicated by the arrows). Kick ’em Jack lies well outside this scarp, ~ 4 km SE of Kick ’em Jenny. Courtesy of NOAA and SRU.

References. Linehan, D., 1940, Earthquakes in the West Indian region: Transactions, American Geophysical Union, Pt. II, p. 229-232.

Mercado-Irizarry, A., and Liu, P. L.-F., 2004, NSF Caribbean Tsunami Workshop, 30-31 March 2004: San Juan Beach Hotel, San Juan, P.R., sponsored by the U. S. National Science Foundation, Puerto Rico State Emergency Management Agency, Department of Marine Sciences at the University of Puerto Rico at Mayagüez, and the Sea Grant Program at the University of Puerto Rico.

Lindsay, J. M., Shepherd, J.B., and Wilson D., 2005, Volcanic and scientific activity at Kick ’em Jenny submarine volcano 2001-2002: Implications for volcanic hazard in the Southern Grenadines, Lesser Antilles: Natural Hazards, v. 31, p. 1-24.

Shepherd, J.B., and Robson, G.R., 1967, The source of the T-phase recorded in the Eastern Caribbean on October 24, 1965: Bull. Seismol. Soc. Amer., v. 57, p. 227-234.

Shepherd, J.B., 2001, Marine and coastal hazards from Kick ’em Jenny submarine volcano, southern Grenadine Islands (copyrighted slide-show presentation): URL:

Shepherd, J.B., 2004, Report on studies of Kick ’em Jenny submarine volcano March 2002 and March 2003 with updated estimates of marine and coastal hazards: The University of the West Indies Seismic Research Unit, KEJ Report Feb 2004, St. Augustine, Trinidad and Tobago, West Indies, 44 p.

Sigurdsson, H., Carey, S., and Wilson, D., 2004, Debris avalanche formation at Kick ’em Jenny submarine volcano, in NSF Caribbean Tsunami Workshop, 30-31 March 2004, San Juan Beach Hotel, San Juan, P.R. (URL:

Smith, M., and Shepherd, J., 1995, Potential Cauchy-Poisson waves generated by submarine eruptions of Kick ’em Jenny volcano: Natural Hazards, v. 11, p. 75-94.

Tolstoy, I., and Ewing, M., 1950, The T phase of shallow-focus earthquakes: Bulletin of the Seismological Society of America, v. 40, p. 25-51.

Walker, D.A., and Hammond, S.R., 1998, Historical Gorda Ridge T-phase swarms; relationships to ridge structure and the tectonic and volcanic state of the ridge during 1964-1966: Deep-Sea Research Part II, v. 45, n. 12, p. 2531-2545.

Information Contacts: Seismic Research Unit (SRU), The University of the West Indies, St. Augustine, Trinidad & Tobago, West Indies (URL:; Research Vessel Ronald H. Brown, National Oceanic and Atmospheric Agency (NOAA), Marine Operations Center, Atlantic, 439 West York Street, Norfolk, VA 23510-1145, USA (URL:

Source: Smithsonian / GVP volcano information

More Information (updated):

Recent Earthquakes Near The Caribbean and Central America

The UWI Seismic Research Centre

USGS GSN Helioplots/Stations
(Data updates automatically every 30 minutes.)

US National Tsunami Warning Center

Pacific Tsunami Warning Center

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