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Extreme Weather in The Caribbean Part 2: Volcanoes

The eruption of La Soufrière volcano at the end of 2020 on the island of St. Vincent. (Photo courtesy of the United Nations website, Rodney Gill photographer)

As mentioned in Part 1 of this series on “Extreme Weather in the Caribbean,” the Caribbean experiences extreme weather incidents aside from hurricanes that can severely impact the USVI and nearby islands. Preparing for dangerous weather events such as volcanic eruptions, earthquakes, and tsunamis is vital.

In the second article in this series, the focus of the discussion will be on volcanic activity in the Caribbean and the potential for volcanic eruptions in the area. For both articles, the Education and Outreach Team at the University of the West Indies spoke to the Source about weather events in the Caribbean Region. The interview information with the UWI team was reviewed by the Director of the Outreach Team at UWI’s Seismic Research Centre, Erouscilla Joseph.

“The UWI Seismic Research Centre is the official source of information on earthquakes and volcanoes in the English-speaking Eastern Caribbean. We currently provide a national seismological and volcanological service for contributing territories in the Eastern Caribbean, as well as support for tsunami warning and public education and awareness on geologic hazards,” Joseph explains.

Caribbean Volcanoes 

The Caribbean Region is home to numerous active volcanoes, and eruptions have occurred as recently as 2021 on the island of St. Vincent. It may only be a matter of time before another eruption occurs at one of the volcanoes in the region.

“The Lesser Antilles includes 21 known, ‘live’ (likely to erupt again) volcanoes spread across 11 volcanically active islands, and volcanic eruptions are one of the main hazards that threaten the Eastern Caribbean region,” said Joseph. “We monitor 16 of the 21 live volcanoes, and they are at alert level green but can have periods of unrest which can include phreatic (steam) eruptions.”

There is one known volcano in the Eastern Caribbean that is active and is located under the ocean surface, called a “submarine” volcano. The name of this volcano is “Kick-‘em-Jenny,” and it is located near the island of Grenada.

“Kick-’em-Jenny, located approximately 8 km north of Grenada (12.18°N, 61.38°W), is the only known ‘live’ submarine volcano in the Eastern Caribbean. This location is in the southern part of the Grenadine Islands, which are themselves in the southern region of the Lesser Antilles island arc. It is the most frequently active volcano in the Eastern Caribbean, erupting at least 14 times since 1939,” according to the UWI website.

“Kick-‘em-Jenny” is the only known, active “submarine volcano” in the Eastern Caribbean. The volcano is located under the ocean surface. (Photo courtesy of the University of the West Indies website)

“The La Soufrière volcano on the island of St. Vincent has had the most recent activity, while the Soufrière Hills volcano in Montserrat is considered to still be ongoing,” Joseph added.

Types of Volcanoes in the Caribbean 

There have been news reports recently about the eruption of “Mauna Loa,” a volcano located on the island of Hawaii. Interestingly, the volcanoes that are in the Caribbean differ from those that are located in the Hawaiian Islands.

“The volcanoes in the Eastern Caribbean are a different type of volcano from the ones in Hawaii. [Hawaiian volcanoes] are ‘shield volcanoes,’ with the magma being more basaltic or less viscous (having a thick, sticky consistency) in nature,” said Joseph.

Map of volcanoes located in the Caribbean Region. (Photo courtesy of VolcanoDiscovery.com)

“Volcanoes in the Caribbean are ‘composite volcanoes,’ with a more andesitic (more viscous) type of magma and more explosive in nature. During the past 200 years, over 30,000 people have been killed by volcanic activity in this region. Currently, about one million people are threatened by the direct effects of volcanic eruptions and about two and a half million more by related phenomena such as volcanic ash fall,” Joseph added.

Danger to the USVI and Puerto Rico

Regardless of precisely where an eruption occurs, the USVI and Puerto Rico could experience effects from an eruption, both physically and economically.

“The closest volcanic islands to the USVI are Saba and St. Eustatius (which do not fall under the monitoring responsibility of The UWI Seismic Research Centre), said Joseph.

“We do, however, monitor St. Kitts and Nevis. Should any volcanic unrest begin at any of these islands, reports or bulletins will be sent to all national disaster agencies within the region. For the USVI, the tsunami threat is minimal due to the location of the volcanic islands. Ash is also a potential hazard, but prevailing winds may negate the impact on the USVI,” stated Joseph.

“The most recent eruption (2020-2021) of La Soufrière in St. Vincent and the Grenadines saw the successful evacuation of approximately 20,000 persons and saw ash from the eruption impact neighboring islands of Barbados and St. Lucia while halting air traffic for several days in that part of the region,” noted Joseph. “The eruption had a significant economic loss for impacted islands. Lahars (mudflows) are a particular volcanic hazard that can occur months and years after an eruption, especially during heavy rainfall episodes or the rainy season.”

Volcanic Earthquakes

The Caribbean regularly experiences temblors. However, certain quakes are related to fault lines and tectonic plates, and others are directly connected to volcanic activity.

“There are different types of earthquakes: regular seismic events that occur at faults along plate boundaries that can cause extensive damage if large enough, and then there are those associated with volcanic unrest. Volcanic earthquakes are associated with volcanic activity and may be a precursory signal that magma might be coming to the surface. These can be micro earthquakes – small signals that indicate the occurrence of volcanic processes may be occurring below the surface,” clarified Joseph.

Types of Temblors

Joseph described different types of quakes that are related to volcanic activity.

“Volcano–tectonic earthquakes are high-frequency vibrations caused by rock fracture (breaks) or minor fault movement associated with deformation (‘swelling’ of the flanks of the volcano). These vibrations are the result of fluids moving through cracks within the earth’s crust.”

“Long-Period Earthquakes are caused by changes in pressure due to movement of magma within the volcano, continued Joseph. “These earthquakes often indicate that a volcano is about to erupt.”

“Hybrid Earthquakes emit seismic signals that combine features of both high-frequency volcano-tectonic earthquakes and low-frequency, long-period earthquakes. They can occur due to the nature of the source zone, e.g., a fluid-filled space. Due to the nature of the rock, the seismic signal travels through on its path to the seismometer,” explained Joseph.

Preparing for a Volcanic Eruption 

“Knowing the potential hazards associated with volcanoes and your location in relation to the volcano is important. The Centre produces volcanic hazard maps that can help people understand the risk posed from the volcano, and all national disaster management organizations have plans and outreach sessions with at-risk communities. Visitors to volcanic islands are also made aware of dangers when visiting sites of volcanic activity. The Centre continues to raise awareness via our social media platforms for all persons to better understand the risk associated with the various geohazards,” noted Joseph.

Volcano Safety Tips 

The University of the West Indies has put together a list of safety tips to follow before, during, and after a volcanic eruption.

BEFORE AN ERUPTION

  • How close is your home to the volcano? Know where the ‘live’ (potentially active) volcanoes are located in relation to where you live. Visit the Island Profile section to see volcanic hazard maps for each island.
  • No volcano on your island? Remember, residents of neighboring non-volcanic islands, e.g., Antigua, Barbados, Trinidad, Tobago, etc., may be impacted by secondary volcanic hazards such as ashfall and the migration of people fleeing the volcanic eruption. During the 1979 eruption of La Soufrière volcano in St. Vincent, ash was recorded as far as Barbados.
  • Stock an emergency supply kit with items that will last you and your family for at least 72 hours (3 days). This should include items like non-perishable food, water, battery-powered radio, batteries, breathing masks for each family member, flashlights, and medication.
  • Volcanoes may move from unrest to full-scale eruption in a short period of time. Therefore, you should have an emergency plan to enable you to evacuate at short notice. Ensure that all family members understand the plan. This should include an evacuation route to get to high ground away from the volcano. If you live in a danger zone (red or orange areas on the volcanic hazard map), make arrangements with friends or relatives in the safe zone (yellow or green areas on the volcanic hazard map) with whom you may be able to stay temporarily during and after an eruption.
  • Volcanoes do not usually erupt suddenly without warning. They are normally preceded by clear signals, which, once recognized, enable timely warnings to be issued. Identify a meeting point to contact family members in the event that warnings are issued when everyone is apart, such as during the day when adults are at work and children are at school.
  • Make a list of emergency numbers, including your national disaster management office, police, fire, hospital, and the nearest emergency shelter.
  • Know what to expect by educating yourself on the impact of volcanic eruptions and relevant safety measures. Get involved in your local disaster management group or conduct online research to learn more.

DURING AN ERUPTION

  • Follow the instructions issued by authorities. During a volcanic crisis, your national disaster management agency and The UWI Seismic Research Centre are the official sources of information.
  • Leave the area promptly if told to do so. Avoid areas downwind of the volcano. Get to high ground away from the volcano.
  • For submarine volcanic eruptions, e.g., Kick-‘em-Jenny, avoid passing near the summit of the volcano by boat. Pay attention to exclusion zone warnings that are in the sea, as boats passing near or over the volcano may sink or be damaged by ejected material.
  • STAY INDOORS. Close all windows and doors.
  • If possible, bring all animals and livestock into closed shelters and store machinery indoors.
  • Beware of hazards such as mudflows or lahars. Avoid low-lying areas where poisonous gases can settle, and flash floods can be most dangerous.
  • Stay out of the high-hazard areas as identified by the authorities. DO NOT attempt to get close to have a look at the erupting volcano!
  • If possible, help others who may require special assistance – infants, the elderly, or the disabled.

AFTER AN ERUPTION

  • Listen to the official radio or television stations, if possible, for the latest information. If you have access to the internet, visit your local disaster management office website or www.uwiseismic.com for regular updates.
  • Be sure to avoid volcanic ash deposits or mudflows/lahars. These are EXTREMELY dangerous and should not be explored. Avoid driving in heavy ash fall since ash can clog engines and stall vehicles.
  • When outdoors, protect yourself with proper clothing, such as long-sleeved shirts and pants.
  • Inhaling volcanic ash is very dangerous to your health. Use a dust mask or damp cloth to help you breathe properly and goggles to protect your eyes.
  • Carefully clear roofs of ash, as accumulated ash is very heavy and can cause roofs to collapse.

Extreme Weather Preparedness 

Preparing for extreme weather events such as volcanic eruptions is essential, just as it is important to be ready for hurricanes. Residents and visitors in the USVI are encouraged to stay updated on weather events on the V.I. Source Weather page and sign up for alerts from the National Weather Service and the Virgin Islands Territorial Emergency Management Agency.

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