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MBARI research helps explain how massive lava fields formed in the Pacific Northwest

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After using autonomous robots to map massive lava fields around Axial Seamount, MBARI researchers used robotic submersibles for targeted sampling of lava and seafloor sediments to understand how and when these fields formed. Image: © 2005 MBARI

MBARI research helps explain how massive lava fields formed in the Pacific Northwest

A colorful scientific figure shows the bathymetry of the seafloor. A key at the bottom right titled Depth (mbsl) shows depth below sea level as a gradient of color from white 2,150 meters below sea level (mbsl) to orange to yellow to blue to dark-blue 2,400 meters below sea level. On the left is a complex of several large drained lava ponds with a yellow edge and blue interior outlined in a dashed black line. The right and bottom axes are labeled with longitude and latitude, respectively.
MBARI’s autonomous underwater vehicles provided high-resolution maps of lava flows (outlined in a dashed black line) that include this 100-meter-deep (330-feet-deep) drained lava pond complex at Axial Seamount. Image: Jennifer Paduan © 2026 MBARI

Volcanic eruptions are significant geologic hazards. Underwater volcanoes are challenging to study, yet they play an integral role in marine geology and may cause destructive tsunamis that can threaten coastal communities.

The Juan de Fuca Ridge is a 500-kilometer (310-mile) volcanic mountain range in the northeast Pacific Ocean, offshore of Oregon and Washington. Axial Seamount is an active volcano along the ridge that has erupted several times since it was discovered in the 1980s. For more than 20 years, MBARI’s Seafloor Mapping Lab and Submarine Volcanism Team have studied this mid-ocean ridge, deploying autonomous underwater vehicles (AUVs) to map the seafloor and remotely operated vehicles (ROVs) to collect observations and samples. MBARI researchers and their collaborators recently shared findings from their work in the scientific journal Geochemistry, Geophysics, Geosystems.

The team found that Axial Seamount has three unusually large lava flow fields on its distal rift zones, spreading out across 65 to 100 square kilometers (25 to 39 square miles) and up to 130 meters (427 feet) thick. These fields include a striking, interconnected series of deep lava ponds unlike any found elsewhere on the seafloor or on land. MBARI research has revealed how these features were formed.

The flows thickened, or “inflated,” when their expansion stalled while their molten interiors continued to expand vertically, overflow, and break out. Deep pits were left behind when their roofs collapsed. The ponds were still molten when a wall broke, and they drained. These large eruptions of lava were fed quickly through dikes from the summit magma chamber. The youngest of the eruptions may have triggered an explosive collapse of the summit caldera—both of these events occurred approximately 1,200 years ago. The other two lava fields are much older, but may also have been associated with caldera collapses. 

Research Publication:

Paduan, J.B., D.A. Clague, D.W. Caress, R. Portner, M. Le Saout, and B. Dreyer. 2026. Voluminous inflated lobate flows on the distal rift zones of Axial Seamount, Juan de Fuca Spreading Ridge. Geochemistry, Geophysics, Geosystems, 27(1): e2025GC012675. https://doi.org/10.1029/2025GC012675

For additional information or images relating to this article, please email pressroom@mbari.org.

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