radhica.sookraj@guardian.co.tt
Geological experts are warning spectators to stay away from the Brickfield mud volcano unless they are accompanied by a tour guide as the explosive mudflow continues to be a hazard.
The volcano, which erupted in July, has emitted rocks about 25 million years old.
In an exclusive interview with Guardian Media, senior geoscientist at Touchstone Exploration, Xavier Moonan said based on historical data and satellite imagery, it appears the recent eruption was the first to have occurred since at least 1940.
“We should note that the mud is still very wet and unstable. Persons should refrain from walking on the mudflow until it dries as they can get stuck quite easily. The short hike to the mudflow is also very moist slippery and uneven. It requires tall boots,” Moonan said.
He noted that the flow is fairly recent.
“We cannot estimate exactly when. The leaves of the trees that fell due to the mudflow are still green but these particular trees can remain with green leaves even after they have been fell for months. The mud itself hasn’t been weathered much, and the flow structures are still very distinct so I would estimate it happened in the last couple weeks at max,” he explained.
Moonan said the mud volcano is located on the Tabaquite fault.
“We know at depth there are the Nariva sands with hydrocarbon and saltwater. Some boulders that were spewed out appear to be of Nariva affinity. These sandstones are approximately 25 million years old. With subtle movement along the Tabaquite fault the water trapped under pressure will escape and entrain mud, resulting in a mudflow at the surface,” he said.
Faults are breaks in the rocks and Moonan explained that this can extend to significant depth in the earth.
“At depths below the Tabaquite area, there are sands with oil gas and saltwater trapped by clays. The movement on the fault allows the trap to break for an instant allowing the water oil and gas to escape. The fluids travel upward to surface where they pick up bits of rocks, clays, sandstones, limestones along the way. This becomes the mudflow that we see at the surface,” he revealed.
Although the Brickfield volcano is located close to Piparo volcano, Moonan said it was not related geologically to the Piparo volcano as both volcanoes occur on separate faults.
“Relatively the mudflow at Brickfield is much smaller in volume than Devils Woodyard. But the flow is still quite extensive measuring up to 165m in length and 76m in width,” he said.
On its Facebook page, the American Association of Professional Geologists Young Professionals Trinidad and Tobago Chapter also said it was hazardous for people to venture alone to see the eruption.
“The Brickfield mud volcano had a very recent explosive/forceful mudflow in a north-westerly direction, ploughing through large palmiste palms and teak trees and producing a clearing of approximately 200 metres long and 40 metres wide from the source of the flow. The flow is now slowly creeping downslope predominantly driven by gravity. The source area continues to bubble profusely with slow streams of mud flowing from scattered small vents,” the AAPG said.
Geological experts have taken sample pebbles, ‘exotic clasts’ from the mudflow.
“These included limestones boulders, chert pebbles, sandstones with hydrocarbon (possibly Nariva member). The mudflow is still very very moist and it should be considered a hazard until the surface has hardened significantly. One can easily get stuck and find themselves in difficulty in the mudflow at present,” the AAPH Trinidad Chapter said.
Hikes are currently being organized by professionals. Persons wishing to visit the Brickfield mud volcano should contact Suresh Roopnarine—282-1958 or Suresh Silochan—368-9976 for a safe, guided tour.