Dec. 6, 2001 – "Kick 'em Jenny," the undersea volcano located just north of Grenada, reawakened from a decade of dormancy on Saturday with earthquakes indicative of eruptions.
By Thursday morning, earthquake activity in and near the volcano had quieted considerably. But scientists feel the threat of further eruption is high, and with it the possibility of tsunami — a huge surface wave generated by such underwater activity.
The University of the West Indies Seismic Research Unit reported the largest earthquake in the present sequence as being about 3.0 on the Richter scale. The SRU also reported that this current earthquake sequence has been considerably weaker than the activity in 1990 when the last significant eruptions occurred. The UWI Seismic Research Unit web site provides updates on the volcano's activity and details of the seismic information it has received.
An Internet update at 11 a..m. Thursday included this statement: "Although eruptive activity seems to have stopped, we are maintaining the alert level at 'orange' [meaning that full eruptive activity may be resumed at very short notice] for at least another 24 hours." It added, "The premonitory earthquake swarms were more severe than any previously observed at Kick 'em Jenny … We are not yet satisfied that the eruption is over."
The statement included a chilling warning to small pleasure craft observed at update time directly over the vent of the volcano: "They should be aware that they could be killed at any moment."
For the duration of an "orange" alert, all shipping is banned from the "first exclusion zone," defined as 1.5 km., or a little less than a mile, from the summit of the volcano. In addition, all non-essential (i.e., pleasure) craft must keep clear of the "second exclusion zone," extending from the first zone to 5.0 km., or a little over 3 miles, from the summit.
The SRU, located in St. Augustine, Trinidad, has been monitoring Kick 'em Jenny for several years, assisted by a recent grant from the Caribbean Development Bank allowing for the placement of instruments to provide continuous monitoring of the volcano. The CDB funds also will support professional and technical staff and services and workshops. The grant, together with another from the U.S. Agency for International Development, also will fund a public information campaign.
Dr. John Shepherd, head of the SRU, said by telephone late Thursday that the "orange" alert will remain in place at least until 10 a.m. Friday, although there had been no eruptive activity since 11 a.m. Thursday. "The buildup to the eruption was big, very big, bigger than in 1990," he said. "The intensity of the eruption itself, however, was lesser than the 1990 event." This combination of factors has led him to keep the alert level high until there's a clear indicator that the activity has subsided indefinitely.
UVI involved in gathering volcano data
The first observed eruptions of the small volcano on the slopes arising from the Grenada Basin of the Caribbean Sea occurred in July 1939. Between then and now, Kick 'em Jenny had erupted 11 times, most recently in 1990. In between, the volcano continued to vent gases non-explosively, much like the volcanoes of Dominica and St. Lucia.
In 1988, vulcanologist Haraldur Sigurdsson descended into the crater. In 1996, he described the experience at a consultation of experts on tsunamis held at the V.I. Experimental Research Station on St. John. At the gathering, sponsored by IOCARIBE, a regional subsidiary of the Intergovernmental Oceanogaphic Commission, the major marine science organization of the United Nations, Sigurdsson related how he had been observing unusual algae inside the crater when warm currents prompted him to return at once to the surface.
In 1996, a highly detailed survey by scientists from the Atlantic Oceanographic and Meteorological Laboratory and the University of the Virgin Islands determined that the volcano's summit lay 178 meters, or about 587 feet, below the surface.
The Kick 'em Jenny image provided on the SRU web page resulted from data collected and processed through the Anegada Climate Tracers Study at UVI, headed by Roy Watlington. Since 1995, ACTS scientists and student interns have made more than a dozen Caribbean marine research trips aboard ships owned by the National Oceanic and Atmospheric Administration, Woods Hole Oceanographic Institute, and the University of Puerto Rico, gathering specific local and Caribbean data.
Shepherd said another survey trip is planned for early next year, with a NOAA ship in the area collecting data relative to climate change. "They will have sidescan sonar," he said, pleased that better equipment will be available for the survey. This, he said, will give a good measure of the distance beneath the surface of the volcano's summit.
"ACTS personnel will play a major role in this expedition to the area of Kick 'em Jenny, as they did in 1996," Watlington said.
As undersea volcano grows, so does tsunami threat
"On Nov. 18, 1867," reads a quotation from "This is Grenada" by Frances Key, published in 1971, "about five o'clock in the afternoon, the water in the harbor [in St. George's, Grenada] dropped five feet … Then the water in the harbor rose quickly to four feet over normal height and rushed up to the head of the Carenage. This happened three or four times. Much damage was done to boats and buildings."
The description is of the great tsunami of 1867 which originated in the Virgin Islands Basin and is familiar to those who have read the book "Disaster and Disruption in 1867."
Now there arises the possibility of a reverse phenomenon: Volcanic activity originating off Grenada could result in a tsunami reaching the Virgin Islands. Watlington cites a 1993 study by Shepherd and Martin Smith which predicted that a tsunami originating from Kick 'em Jenny would reach St. Croix in about 80 minutes, and the northern Virgin Islands about 10 minutes later.
The energy of a Kick 'em Jenny eruption is suppressed because of the current depth of the volcano beneath the surface. Watlington notes, "If the volcano continues to grow, more of its energy could be released, leading to the generation of tsunami waves."
Despite the warnings from scientists, disaster officials do not yet have a tsunami warning system in place throughout the Caribbean. The SRU and the Puerto Rico Seismic Network update their sites continually to provide current local information.
Editor's note: Source contributor and retired librarian Shirley Lincoln and UVI chancellor and marine science faculty member Roy Watlington compiled archival writings about the three great natural disasters that all struck the Virgin Islands in one year for publication as the book "Disaster and Disruption in 1867: Hurricane, Earthquake and Tsunami in the Danish West Indies."
