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Seismic Research Unit visit Radix Point mud volcano30 July, 2007 Staff from the Seismic Research Unit took part in a boat trip on 28th July to investigate the sea disturbance near Radix Point. The observations confirmed that the cause of the disturbance was almost certainly an underwater mud volcano. On this visit, the brown discoloration was drifting to the south east. It was not continuous and there were some discrete spots of muddy water, about 10 or 15 metres in diameter. There was no evidence of anything being forecefully ejected from the sea - all we saw were breaking waves. The waves were big enough to capsize a small boat, so no close-in observations were attempted.
View of the disturbance from Radix Point. Click on the image for a larger view.
Map showing the GPS track for the trip. The red dot shows the location that had been reported to us. Click on the image for a larger view.
Waves breaking over the disturbance. At times the waves were more than two metres high. Click on the image for a larger view.
Waves breaking over the disturbance. Click on the image for a larger view.
Waves breaking over the disturbance - sometimes this kicks up spray that appears like a water jet. Click on the image for a larger view.
A discrete region of muddy water. Click on the image for a larger view.
Taking a water sample. Click on the image for a larger view.
Waves breaking over the disturbance. Click on the image for a larger view.
Waves breaking over the disturbance. Click on the image for a larger view.
Setting off for home. Click on the image for a larger view.More information about mud volcanoes in Trinidad and Tobago can be found at the Geological Society of Trinidad and Tobago’s website (http://www.gstt.org/teaching/mud%20volcanoes.htm). Seismic Research Unit investigates sea disturbance near Radix Point26 July, 2007 The Seismic Research Unit have confirmed reports of a disturbance at sea, about five miles east of Radix Point on the east coast of Trinidad. This is probably caused by an underwater mud volcano, similar to that at Chatham Island and several on-shore mud volcanoes in Trinidad. Staff of Repsol YPF, who regularly fly over the area, reported a "bubbling of the sea" and extensive brown discoloration of the sea water since about July 11. The location was given as 10 degrees 22.498 minutes N, 60 degrees 55.322 minutes W.
General view of the disturbance showing circular pattern of waves. Click on the image for a larger view.Dr Richard Robertson, Director of the SRU, viewed the site from a helicopter on 24 July. The sea was calm. The disturbance consisted of a region of breaking waves, about seven to ten metres in diameter. This was partially surrounded by a region of light-brown discoloured seawater. The waves were breaking east to west over an underwater feature. The feature could not be seen but could have only been, at most, a few feet below the surface. There was also a circular pattern of small waves, centred on the disturbance. There was no evidence of any bubbling or gas emissions that might drive such waves, and the circular pattern was probably generated by waves that are reflected and refracted by the source region.
Waves breaking over the underwater feature. Click on the image for a larger view.The discoloration was being carried to the north-northeast by the prevailing currents, disappearing completely at a range of about 100 metres (350 feet).
This view shows what appear to be distinct plumes of material beneath the water's surface. Click on the image for a larger view.Close examination revealed a number of discrete brown plumes of material which appeared to be coming from shallow vents. These could be seen on the south and west margins of the disturbed area, although other sources might have been be obscured by the muddy water.
Close up of "plumes". Click on the image for a larger view.SRU also received reports from people who were diving in the area about two months ago. They observed brown material coming from what appeared to be a single vent on the sea floor, about 15 metres (50 feet) below the surface. Bathymetric charts, last updated in 1931, show water depths of about 15 metres (50 feet) in this area.
Section of Admiralty Chart 483B showing the location of the disturbance. Click on the image for a larger view.All the observations suggest the source is an underwater mud volcano. The extrusion of mud over a period of about two months appears to have built up a 15 metre (50 feet) high mount which is now just below the water surface. This is very similar to the activity at Chatham Island, which produced short-lived islands in 1964 and 2001. It is not possible to say how long the activity will continue and whether it will result in the creation of an island like Chatham Island. The edifice is subject to much greater erosion nearer the sea surface, so may never break the surface. The hazards generated by this activity are very localised. There is a real danger to any boats that approach the disturbed area and sailors are encouraged to adopt a cautious approach and stay more than one mile from the disturbance. More information about mud volcanoes in Trinidad and Tobago can be found at the Geological Society of Trinidad and Tobago’s website (http://www.gstt.org/teaching/mud%20volcanoes.htm). Update: Changes Observed at the Boiling Lake, Dominica14 January, 2005 The Seismic Research Unit has been notified by Forestry Officers of the Forestry & Wildlife Division of Dominica that the water level and geothermal activity of the Boiling Lake, Dominica have been gradually returning to its normal status. Field visits by Forestry Officers on Tuesday 18th January, as well as reports from other visitors to the Lake, have confirmed that the water levels in the Lake is now ~20ft below the high water mark. In addition, there has been an increase in the degassing of the submerged fumaroles within the Lake, which can now be observed as bubbling of the water at the Lake’s surface. These changes in the activity of the Boiling Lake are again believed to be a reflection of local changes in the geothermal system, and are not related to any changes in the level of volcanic activity. We still wish to emphasize that people exercise extreme caution when visiting the Lake in its current state. Specifically we recommend that: 1) No one climbs down to the water’s edge at this time, and 2) Visitors to the Valley of Desolation either avoid approaching the Lake and/or spend as little time as possible at the viewing point on the crater rim. In the meantime, if anyone notices any further changes in Dominica’s geothermal areas, they should contact the Seismic Research Unit (uwiseismic@uwiseismic.com).
Boiling Lake, Dominica, with increased water levels.Changes Observed at the Boiling Lake, Dominica30 December, 2004 The Seismic Research Unit has been notified by Forestry Officers of the Forestry & Wildlife Division of Dominica that the water level and geothermal activity of the Boiling Lake, Dominica have significantly decreased. On December 28th a team of Officers were sent to investigate the situation and were able to verify that the water levels in the Lake had dropped by approximately 30 - 40ft. In addition there was no vigorous boiling or steaming, and the lake’s temperature was much lower than as is usually observed. The Boiling Lake has been known to undergo changes in the past, and a reduction in water level has been observed on four previous occasions: April-May 1988, April 1971, January 1901, and December 1900. The historical record as well as the present day volcano monitoring network indicate that these past incidents reflected local changes in the geothermal system, and were not related to any changes in the level of volcanic activity. Similarly the recent changes in activity may have resulted from changes in permeability of the rock materials beneath the Boiling Lake along with blockage of fumarolic vents in the crater. An increase in permeability of the subsurface layers would enable the crater waters to drain away faster than they are being replenished by the two surface streams. Blockage of the fumarolic vents would lead to a reduction in steam emission and hence in the temperature of the crater water. Given the recurrent nature of the recent changes at the Boiling Lake, scientists at the Seismic Research Unit will undertake an investigation so as to better understand the causes. Despite the fact that it is unrelated to any increase in volcanic activity the recent changes at the Boiling Lake does increase the potential hazards to visitors to the area. In 1901 a small steam and gas explosion from the Boiling Lake (which was almost empty at the time) released harmful gases (probably mainly carbon dioxide) into the atmosphere and killed two people who were at the water’s edge at the time. This event highlights one of the main potential dangers of the Boiling Lake, especially at times of unusual activity. For this reason, we recommend that people exercise extreme caution when visiting the Lake in its current state. Specifically we recommend that: 1) No one climbs down to the water’s edge at this time, and 2) Visitors to the Valley of Desolation either avoid approaching the Lake and/or spend as little time as possible at the viewing point on the crater rim.
Boiling Lake, Dominica, with decreased water levels. Click on the image for a larger view.In the meantime, if anyone notices any further changes in Dominica’s geothermal areas, they should contact the Seismic Research Unit at uwiseismic@uwiseismic.com.
New seismograph station in St. Martin8th March 2004
______________________________________________________________________________________ 25th February 2004New Staff membersAfter long and frustrating delays caused mainly by the UWI administration the two posts advertised on this site and elsewhere have finally been filled. The post of GEOPHYSICIST has been offered to and accepted by Ms. Rosemary Mohais and the post of VOLCANOLOGIST by Dr. Nicholas Fournier. As noted previously, the lists of applicants for both posts was extremely strong and the choices were particularly difficult. The university administration should by now have contacted all unsuccessful applicants. We thank them all for their interest in the Seismic Research Unit. Inaugural Graduate Student's Conference in JamaicaThe Mona Association of Postgraduate Students (MAPS) and the School for Graduate Studies and Research, University of the West Indies (UWI), in collaboration with the Research Consortium, Jamaica presented its Inaugural Graduate Student's Conference on 19-20 February 2004. This conference was held at the Mona campus of UWI and its theme was "Graduate Studies and Research: Imperatives for Regional Growth and Development." There were over thirty-five (35) presentations by graduate students in various research fields during the course of the conference. The main aims achieved by the symposium were to facilitate meaningful dialogue on topical issues facing the region, and the promotion and exposure of the wealth of research being done by graduate students at UWI and other tertiary institutions. Patricia Joseph of the Seisimic Research Unit presented a paper entitled "Implementation of a geothermal monitoring program for the islands of the Lesser Antilles: Challenges and preliminary results". A copy of the presentation can be found here. ____________________________________________________________________________________ 28-31st December 2003Mystery surrounding large number of small seismic events recorded on Saba seismograph9:00AM Wednesday 31 December 2003Investigations instigated by the Lieutenant-Governor of Saba Mr. Antoine Solagnier have identified the source of the seismic events recorded over the past ten days. The main pier of the harbour in Saba was damaged by hurricane Lenny in 1999 and is now being demolished in preparation for replacement. It is being demolished by a crane which hoists a ten-tonne mass to a height of approximately 25 meters and then drops the weight onto the pier. The demolition site is about one kilometer horizontally and 320 meter vertically from our seismograph station and the energy generated bythe impcts is entirely sufficient to explain the observed signals. Update 5 PM Tuesday 30 December 2003The seismic events in Saba have continued at a rate of about one every five minutes throughout the afternoon. The events are spaced extremely regularly, and occur only during daylight hours which suggests an artificial origin but investigations in Saba have not yet identified a possible cause. Update 12 Noon Tuesday December 30 The sequence of seismic events in the island of Saba which began last week and continued to December 28 was renewed briefly today, December 30, when seven (7) events occurred in rapid succession between 10:43 AM and 11:00 AM Local Time. Saba is the smallest island under separate administration in the eastern Caribbean and essentially consists of the single volcano Mt. Scenery. Pictures and descriptions of Mt. Scenery can be found on the Documents section of this site. The most recent severe earthquake swarm near Saba occurred in 1992 (Ambeh and Lynch, Tectonophysics 246 (1995) 225-243. These authors considered that the 1992 events had a tectonic rather than volcanic origin. The ongoing events are much smaller than those of 1992 and the most likely explanation at the moment is that they are of artificial origin. No descriptions of volcanic eruptions in Saba have been found in the literature written since Europeans first began to settle there in 1640 AD. This is slightly puzzling because the youngest pyroclastic flow deposits in the island contain fragments of European pottery, and a radiocarbon date for these deposits suggests that they were erupted in 1670 AD (+/- 60 years). Other radiocarbon dates for different deposits are 1425 AD (+/- 60 years), 3,155 +/- 65 years and 34,750 (+/-850 ) before present. The more recent eruptions occurred while the island was occupied by Amerindians and the most recent may have been since European settlement. Further literature searches may yet yield descriptions of this event (or events). 28 December 2003Over the Christmas period and continuing to Sunday December 28 our seismograph station in Saba recorded a very large number of small seismic events. At the moment we are uncertain whether these are genuine earthquakes or whether the signals are generated by some other activity such as onshore or offshore explosions. All that we know is that the signals are being generated on or close to the island of Saba, in the Netherlands Antilles. If anyone can cast any light on these phenomena please e-mail us at uwiseismic@uwiseismic.com. ____________________________________________________________________________5th June 2003New monitoring developments in DominicaSince the last report was issued on April 22 there have been two new developments. We have installed an extra seismograph station at Hillcrest Estate House in northern Dominica (DHCT on the map below). This station is in the middle of the source zone of the current activity and will improve the quality of earthquake locations considerably. There are now four state-of-the-art seismograph stations in northern Dominica at the locations shown in the next diagram as solid stars. |
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Photo courtesy Arlington James
