Fast magma refills suggest some volcanoes connect straight to the mantle

Irazu volcano climbs 3,432 m above Costa Rica.

Rafael Golan/Wikimedia

Because of their location’s geology, Icelandic volcanoes are known to be directly connected to the Earth’s mantle. New research shows that a volcano in Costa Rica may have a direct connection to the mantle too, despite lying on a much thicker part of Earth’s crust. This discovery suggests that eruptions in a wider range of volcanoes might be predicted by techniques such as earthquake monitoring, something proposed for Icelandic volcanoes. But it also suggests that volcanoes can recharge with magma very quickly, raising the risk of a sudden eruption.

Tectonic plates cover the Earth’s surface. The boundaries between these plates can be dangerous places, with earthquakes, volcanoes, and tsunamis all originating along the places where plates meet. The plates create two types of volcanoes. Those that sit on oceanic crust are directly connected to the mantle (the thick layer between the Earth’s crust and molten outer core); they spew magma directly from it. Others erupt magma that has been heated, mixed and stored in magma chambers over an extended period. These are assumed to lack a direct connection to the mantle.

Icelandic volcanoes are an example of the former, occurring on the mid-ocean ridge of the North Atlantic where crust is constantly being created. In contrast, most volcanoes around the Pacific rim, including the Costa Rican volcano, have been assumed to be examples of the latter.