Magma appears to be traveling an unusual path beneath the volcano. This new knowledge reveals information about the mechanisms underlying eruptions.
A study conducted by researchers at Imperial College London, shows that rising and spewing magma does not always follow the quickest and most direct route to reach a volcano's surface.
This research can provide some insight into the reasons why some volcanoes are more active than others and why volcanic activity changes over time.
When two tectonic plates collide, the denser plate can sink under (or subduct) the other and plunge between 10 and 100 kilometers deep into Earth's mantle.
These harsh conditions force water and other volatile substances to be trapped. Such fluids make up an important component of magma in volcanic arcs such as those found in the Pacific Ring of Fire.
However, the route of these fluids through Earth's interior, from subducting plates to volcanic arcs, needs to be better understood.
Where does magma erupt?
The team used seafloor seismometers to collect seismic (earthquake) data from subduction zones in the Eastern Caribbean. This area gave rise to the volcanic island of the Lesser Antilles.
They use an approach by looking at the waves generated by the earthquake. These waves slow down or speed up as they pass through various materials. In addition, waves also experience a change in energy.
Knowing that hot, molten rock is highly 'weakening' (or absorbent), researchers use this understanding to identify where magma is at depth. They then use this data to create a precise 3D model of the subsurface.
Unusually, the investigation found that the zone of strongest seismic attenuation was displaced laterally from beneath the volcano.
The map led the researchers to conclude that as water is forced away from the subducting plate, it is dragged deeper, melting the mantle beneath the volcanic front.
After that, the melt collects at the base of the underriding plate, then is transferred back into the volcanic arc.
"Scientific views on this much-debated subject have traditionally fallen into two areas. Some believe subducting plates largely control where volcanoes are located, and some think the overlying plates play the largest role," said study lead author Dr. Stephen Hicks, quoted from Interesting Engineering.
"But in our research, we show that the interaction of these two driving forces over hundreds of millions of years is the key to controlling where eruptions are occurring today," he said.
Hicks also highlighted that the team's research provides important information about the mechanisms underlying volcanic eruptions. This information can improve understanding of the formation and addition of magma reservoirs beneath volcanoes.
The paper was published in Science Advances on February 1 and is the result of an international collaboration between scientists from the UK, US, Germany and Trinidad.