Unveiling Kīlauea's New Puʻu: A Geologist's Journey
Kīlauea, the Hawaiian volcano, has been in the news for its recent eruptions and the formation of a new puʻu (a small volcanic cone). This article takes us on a journey through the eyes of a geologist, tracking the growth of this new feature and the innovative methods used to study it.
The Challenge of Tracking Tephra
The story begins with the challenge of measuring tephra, the rock fragments ejected during an eruption, including Pele's hair. Initially, geologists attempted to track the accumulation of tephra by photographing a road sign, but as the puʻu grew, this method became impractical. Garden stakes were then used to measure tephra accumulation, but the puʻu's rapid growth made this approach insufficient.
High-Tech Solutions: GPS and Lidar
To overcome these challenges, HVO geologists turned to advanced technology. They employed GPS (Global Positioning System) instruments, which use satellite signals to precisely measure locations. By walking transects along the closed road, they could track the puʻu's growth over time. This method, combined with lidar (light detection and ranging) data collected in 2019, provided a detailed understanding of the puʻu's elevation changes.
Airborne Lidar: A New Perspective
HVO also utilized a new helicopter-mounted airborne lidar system, offering high-resolution three-dimensional topographic scans of the puʻu. This technology, processed monthly, provides valuable insights into the puʻu's structure and growth. However, photogrammetry methods, used to track elevation changes on the crater floor, have been less successful due to the puʻu's uniform surface.
Rapid Growth During Fountaining Episodes
The data collected highlights the puʻu's rapid growth during lava fountaining episodes. For instance, at the site of the buried road sign, tephra accumulated to a thickness of 3.4 meters (11 feet) after Episode 23. Episode 24 added an astonishing 7.8 meters (25.6 feet) in just 7.5 hours, while Episode 36 contributed an additional 7.5 meters (24.6 feet) in a mere 5 hours.
The Puʻu's Evolution
The puʻu's growth is most significant during high-fountaining episodes exceeding 300 meters (1,000 feet) in height. This rapid growth occurs when lava fountains are below the rim, making it challenging for tephra to reach the new puʻu. Pele's current activity marks a return to the site where visitors once drove around Halemaʻumaʻu, now a testament to the volcano's dynamic nature.
Volcano Activity Updates
Kīlauea's eruption continues, with Episode 37 lasting 9 hours on November 25. The summit is reinflating, and glow has been visible at both vents. Another fountaining episode is expected between December 6 and 9. No unusual activity has been reported along the East Rift Zone or Southwest Rift Zone.
Mauna Loa, on the other hand, remains calm, with no eruptions and a normal USGS Volcano Alert Level. A minor earthquake was felt near Pāhala on November 29, but HVO continues to monitor both volcanoes closely.
For more information, visit the HVO website, which offers a wealth of resources, including past Volcano Watch articles, Kīlauea and Mauna Loa updates, volcano photos, maps, and recent earthquake data. Email inquiries can be directed to askHVO@usgs.gov.
