Using Ambient Noise to Track Magma Migration

Using ambient noise from waves and wind, scientists have found a novel way to understand how magma flows underground in relation to a caldera.

IMAGE: For the first time ever, researchers used seismic noise to observe the movement of volcanic material at depth. CREDIT: Elisabetta Cipolla

Back here on Earth, we’re once again held captive and fascinated by the power and awesomeness of volcanoes. I don’t think we can overstate the love that our team has for these powerful structures, no matter the type: cinder cones like in La Palma and Iceland, shield volcanoes like Kīlauea, or stratovolcanoes like those in the Andes and Japan. And we even love a type of volcano that seems a bit misunderstood, in my opinion — the caldera. Of course, most of us are familiar with the huge caldera under Yellowstone, but that’s one of many here on Earth.

New research published in Nature Communications and led by Dr. Simona Petrosino has found a novel way to understand just how liquids, in this case magma, flow underground when it comes to caldera. Specifically, the team used ambient noise from the sea and the wind to map processes deep beneath the earth in a region known as the Phlegraen Fields, or Campi Felgrei, in Italy.

Dr. Petrosino explains: Sea and wind constantly interact with the caldera and produce waves that scan its depths. Ambient noise waves enter the caldera with their direction changing above faults and magma feeding systems. Our work shows that, while the change of direction is essential to detect structures, the loss of any directionality is a signal of activation. The energy release is followed by migrations of fluids that produce additional noise sources, hindering our ability to reconstruct directionality. Thus, the loss of directionality gives us a tool to track the migration of deep fluids before they reach the surface.

When scientists analyzed noise data that was collected over the last decade, they found just such a loss of directionality in 2018, which corresponds to a time when some of those deep magmatic fluids migrated up into more shallow hydrothermal systems. That migration likely caused the earthquakes felt in the region in 2019.

Co-author De Siena goes on to further explain: The volcano releases its stress through migrations of fluids following paths opened during its intense activity in…