Montserrat Seminar

Intro

Bill

Ryan

Erin

Hester:

Soufriere Hills is the active lava dome on Montserrat. A lava dome forms when thick, viscous lava with a high concentration of crystals is extruded from a volcano at relatively low speeds. This typically occurs at andesitic, dacitic, or rhyolitic volcanoes. Instead of flowing easily away from the vent (like a basalt volcano) or erupting explosively, these lava flows ooze out of the ground and stay in place.

Soufriere Hills began erupting in 1995 with a series of phreatic (steam) eruptions. These transitioned to explosive eruptions and dome collapses. When a lava dome collapses, it forms pyroclastic flows. Pyroclastic flows are very dense currents that contain a mixture of gas, ash, pumic, and boulders. Pyroclastic flows that form due to a dome collapse are composed of the materials that made up the dome - namely, blocks of lava and ash particles.

Soufriere Hills is not usually visible, due to thick clouds, however we were lucky enough to see it one evening.

This close-up of the Soufriere Hills dome shows the active fumeroles. Fumeroles are places where hot gas and steam is released. The yellow patches may be hydrothermal alteration.

With Dr. Stinton, we went into the old capitol town of Plymouth. Plymouth was evacuated after Soufriere Hills became active, and was destroyed in a block-and-ash flow in 1997.

The boulder lodged through this building demonstrates the sheer power and carrying capacity of a block-and-ash flow.

We saw many more of these boulders when we visited Trants with Dr. Stinton. These boulders don't look very large, but were sometimes the size of school buses. The foot of Soufriere Hills is visible in the background.

We got to visit several of these boulders up close, and each had an interesting story to tell. This boulder has horizontal bands that formed as the lava was slowly flowing out into the dome.

When we flew off the island, we got a great view of the pyroclastic flow & lahar deposits at Trants. As you can see, these deposits actually pushed out into the ocean, increasing the size of the island and creating new land.

We were also privileged to receive a behind-the-scenes tour of the Montserrat Volcano Observatory. Soufriere Hills is monitored with remote video cameras and thermal cameras, which can be seen behind Chris and Jarad.

Soufriere Hills is also monitored with many seismic stations. Here Dr. Rob Stewart shows Erin and Shannon some seismic data from before the last major eruption.

Soufriere Hills is also monitored visually, as Ryan and Justin demonstrate.

We also go to see a hummingbird nest on our rainforest hike:

I also found out that my favorite plant is not native to nurseries in North America:

We also got to look at deposits exposed in cliffs (and enjoy the beach!)

Jerad

Chris B

Chris Mudge:

Forest Walk

Beach

Radio Station ZJB- Radio Montserrat

Our Ride off the Island

The Beast Shows itself

The reefs of Montserrat are found on the north and western shorelines. Generally reefs are in good health and show a diversity of vertebrates and invertebrates. Invasive species that exist in the region effect reef community dynamics, and include; Lion fish introduced from the indo-pacific region, and Orange cup coral. Lion fish are an aggression predator of juvenile fish and are prolific breeders. Orange cup coral is the only stony coral to be introduced within the Caribbean and western Atlantic, and is also sourced from the indo-Pacific region. Healthy native species include pillar coral (Dendrogya cylindrus), elkhorn coral (Acropora palmata), barrel sponges, brian coral (scleractinia), turf grass, udotea (green algae), halimeda (green algae), penicilus, red algae, diadema (echinoid), and numerous fish species. Volcanic sediments, hurricane activity, and disease now effect coral communities creating whitings (dead coral) in the region.

Wyatt Petersen

Looking into the short term and potentially long term effects of volcanic deposits on top of reef systems seemed like a natural choice when considering that we would be on a Caribbean island with an active volcanic system along with a reef to potentially explore. What I ended up finding was that overall the reef was doing okay considering that many of the warm water reefs (globally) have been cited as showing as much as a 40% decline in overall coral coverage. The system here is dealing with all of the same limiting factors as the other warm water reefs, and has the added disadvantage of being consistently covered in new debris from El Soufriere. The volcanic system here not only inundates the reef with andesitic debris during explosive events, but will continue contributing to the reef areas close to the shore through lahars and degradation of the pumice and block and ash flows over time. There are currently efforts being made on the western side of the island to propagate reef growth with the use of reef balls, and the reef is showing signs of growth for the future in young corals, juvenile fish, and overall growth. This system is something to keep an eye on with respect to possible future study, and possibly understanding exactly what will happen to these extremely important and delicate systems with the almost constant stress being applied through active volcanism.

Corals of Montserrat Sway by Wyatt Petersen

Justin

Conclusions

References used: