An international team of volcanologists went to the Galápagos Islands to study boring volcanoes, but they were surprised to find chemically diverse magmas beneath these seemingly predictable mounts, as reported by Earth.com.
"This was unexpected," Trinity College Dublin's Dr. Michael Stock said. The study's lead author also said they started the study "to know why these volcanoes were so boring." They were also curious about how the erupted lava compositions remain constant over long timescales. "Instead we found that they aren't boring at all - they just hide these secret magmas under the ground," Dr. Stock said.
In some places like Hawaii and the Galápagos Islands, volcanoes produce slow-moving lava flows for millions of years. These streams of fire are destructive, but usually not life-threatening. In contrast, researchers found that volcanoes producing minor basaltic lava eruptions may be hiding magmas and trigger explosive activity.
What's underneath Galápagos volcanoes?
Scientists studied two Galápagos volcanoes that have consistently emitted basaltic lava flows throughout their history. They studied the lava composition of microscopic crystals to learn the chemical characteristics of magmas underneath.
Surprisingly, these magmas were extremely diverse and contained compositions similar to those from Mt. St. Helens.
Dr. Stock said their findings, which were published in Nature on July 28, did not show any sign that these Galápagos volcanoes will experience a shift in eruption style, although these results may explain why other volcanoes "have changed their eruptive behavior."
Volcanologists said volcanoes constantly emit these compositionally uniform basaltic lavas when the magma is high enough to flush through the ground and "overprint" any chemical diversity. This trend may happen when a volcano is near a hot spot where magma plumes arise from beneath the Earth. Moreover, these magmas could become mobile and rise toward the surface to produce unexpected activity.
The findings would help scientists understand the risks presented by different volcanoes worldwide. It does not mean that if volcanoes have always erupted in a certain way in the past, it would continue to act the same way into the future.
The study also led the scientists to better understand the volcanoes' behaviors, which is important in hazard assessment and volcano monitoring.
"This discovery is a game-changer because it allows us to reconcile divergent observations, such as the presence of explosive deposits at several Galápagos volcanoes," study co-author Dr. Benjamin Bernard said.
What's in Galápagos?
The western Galápagos Archipelago hosts several volcanoes that have erupted near-homogeneous basaltic magmas for several millennia. This makes the area an ideal location for volcanologists who research on compositionally monotonous volcanism.
Galápagos volcanoes include Fernandina island's Fernandina as well as Isabela Island's Wolf, Darwin, Ecuador, and Sierra Negra volcanoes. All of their basalts experienced extensive clinopyroxene, olivine, and plagioclase crystallization. Among these volcanoes, Fernandina and Isabela are located near the center of the Galápagos plume.
In January, volcanic activities were seen from the La Cumbre volcano on Fernandina Island in the Galápagos as it spewed volcanic ash and spilled lava down to the sea.
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