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Two Magma Reservoirs Mapped Beneath Kīlauea

A dense seismometer array gives a sharper picture of volcano plumbing, with the two zones still separate near the surface.

Updated on Nov. 3, 2026 in Geology

Wide view of a dark basalt volcanic caldera under low morning light, with a steaming crater in the distance and sensor pedestals on the grey rock.
Researchers mapped two separate magma storage reservoirs beneath Hawaii's Kīlauea volcano, one under Halemaʻumaʻu crater and one under the south caldera. AI Illustration. Upload story photo >

Researchers have identified two separate magma storage reservoirs beneath Kīlauea's summit in Hawaii, one beneath the Halemaʻumaʻu crater and one beneath the south caldera. The findings come from a study published in Journal of Geophysical Research: Solid Earth and are research-stage results rather than a settled model of the volcano's plumbing.

Why it matters

Scientists previously lacked a sharp seismic image of magma storage beneath the summit, and the new map reveals a subsurface structure that differs from a single shared chamber. The work comes as Kīlauea has been erupting again since late 2024, a period when understanding where magma sits and how it moves is central to forecasting eruptions.

The study combined natural seismic signals with artificial signals from the T-Rex vibroseis truck, which produces controlled vibrations, across a 1,815-instrument array. The denser coverage is what allowed a sharper image than earlier sparse networks could produce.

The players

Kīlauea

An active shield volcano on Hawaiʻi Island whose summit caldera and eruptive record since 1983 make it one of the most closely monitored volcanoes in the United States.

Journal of Geophysical Research: Solid Earth

A peer-reviewed American Geophysical Union journal that publishes research on the composition, structure and dynamics of Earth's solid interior.

The details

Seismometers record ground vibrations, and by tracking how seismic waves travel through rock, geologists can infer what lies beneath the surface. The team used a dense network of 1,815 seismometers that captured both natural earthquakes and vibrations from the T-Rex vibroseis truck, a vehicle that generates controlled, known vibrations, known as active-source seismology. Comparing how those waves bounced and slowed through rock revealed two distinct zones where magma is stored, one beneath Halemaʻumaʻu crater and one beneath the south caldera.

Timeline

  1. Kīlauea erupted almost continuously from 1983 to 2018.

  2. Kīlauea began a new series of eruptions in late 2024 that continue as of late 2026.

  3. The study was published in Journal of Geophysical Research: Solid Earth in 2026.

The Tech Race

Active-source seismology using controlled vibration trucks alongside passive natural-signal monitoring is a methodological approach that could be applied at other active volcanoes or seismically interesting sites. The study therefore points toward denser, hybrid sensing as a route to sharper subsurface imaging across the field.

The findings are research-stage and do not change current monitoring or alerts for Hawaii residents or visitors. Practical effects would depend on whether denser seismometer arrays are later deployed at other volcanoes, and no timeline for that has been announced.

The takeaway

Watch for follow-up work that tests whether the two Kīlauea reservoirs connect at greater depth, which the researchers have only projected. Also track whether the hybrid natural-plus-vibroseis method is adopted at other active volcanoes.

Further reading

For more on how scientists read the interior of active volcanoes, explore Geology coverage.

Source note: This article includes information reported by Eos.