Hiking on the boardwalk at Haʻakulamanu, also known as Sulphur Banks, in Hawaiʻi Volcanoes National Park, is a multisensory experience. You can feel warmer temperatures as you walk by cracks emitting steam, smell the sulfury deposits in the air, and see vibrant colors associated with crystal growth and degassing in this long-lived fumarolic area near the summit of Kīlauea. You may not notice an unassuming pile of rocks just off the boardwalk that marks the beginning of more than a century of geochemical research at Kīlauea.

In 1922, USGS Hawaiian Volcano Observatory founder Dr. Thomas Jaggar had a big question: could measuring heat underground help scientists understand when volcanic eruptions might occur?

To find out, Jaggar and his team drilled a series of shallow wells near the steaming fumaroles of Haʻakulamanu. The work was tough. Water had to be hauled by hand, drill bits were manually operated, and scalding steam and gases constantly challenged the crew.

What they found was remarkable. Just ten feet below the surface, temperatures reached the boiling point of water and stayed there. Gas samples collected from the wells matched those from natural degassing areas, called fumaroles, providing some of the earliest clues that these gases came directly from magma beneath Kīlauea's caldera.

More than 100 years later, scientists still monitor gases at this site, continuing the work Jaggar began. So when you visit Haʻakulamanu, remember: beneath that humble pile of rubble lies the foundation of modern volcanic geochemistry in Hawaiʻi.

Mahalo for listening, I’m Katie Mulliken and this was your weekly volcano minute brought to you by the USGS Hawaiian Volcano Observatory.