An international team of researchers discovered that the Galápagos’ volcanoes get their fuel from a source that’s 1,200 mi deep within the ocean. Known as a “mantle plume,” this narrow conduit sends hot rock to the surface. Although mantle plumes came onto scientists’ radar in the 1970s, they have escaped detailed seismic imaging, since their locations are often far away from seismic stations.
However, seismic floats known as Mobile Earthquake Recording in Marine Areas by Independent Divers (MERMAIDs), aim to shift that trend. MERMAIDs passively drift 2-3 mi per day, at a depth of about 1 mi (1,500 m) below the ocean’s surface. If a float detects an incoming earthquake, it’ll rise to the surface within 95 minutes so it can figure out its position via GPS and send the seismic data.
Nine floating robots were involved in a 2-year study. During that time, the researchers were able to create an artificial network of oceanic seismometers that could help regions with previously unknown seismic information. The red dots in the image below show where the MERMAIDs picked up a seismic signal throughout the study’s duration.
The results showed surprisingly high temperatures, which “hints at the important role that plumes play in the mechanism that allows the Earth to keep itself warm,” Guust Nolet, one of the authors of the study, says.
“Since the 19th century, when Lord Kelvin predicted that Earth should cool to be a dead planet within a hundred million years, geophysicists have struggled with the mystery that the Earth has kept a fairly constant temperature over more than 4.5 billion years,” Nolet says.
“It could have done so only if some of the original heat from its accretion, and that created since by radioactive minerals, could stay locked inside the lower mantle. But most models of the Earth predict that the mantle should be convecting vigorously and releasing this heat much more quickly. These results of the Galápagos experiment point to an alternative explanation: the lower mantle may well resist convection, and instead only bring heat to the surface in the form of mantle plumes such as the ones creating Galápagos and Hawaii,” Nolet explains.
China’s Southern University of Science and Technology (SUSTech) intends to join the international crew. Together, they will launch 50 more MERMAIDs in the South Pacific to study a mantle plume underneath Tahiti. The team has dubbed the next phase of their research as EarthScope-Oceans.
To learn more, read the study, “Imaging the Galápagos mantle plume with an unconventional application of floating seismometers,” published in Scientific Reports