Hazardous explosive eruption cycles at K?lauea volcano, hawai?I

The National Science Foundation Office of Integrative Activities awarded the University of Hawaii at Manoa $403,097 on October 15, 2026, under the Geosciences program (CFDA 47.050) to investigate explosive eruption cycles at Kīlauea Volcano on the Island of Hawai'i.

The project will examine the Pahala Tephra, a proposed 10,000-year-long explosive eruptive cycle with ash and pyroclastic deposits emplaced between approximately 30,000 and 3,500 years ago. The research combines field stratigraphic and dispersal mapping of tephra units, radiocarbon dating of intercalated charcoal to constrain eruption timing and cycle duration, and textural analysis of pyroclast groundmass and vesicles to estimate magma conditions. The investigators will determine when the explosive episode occurred and what internal volcanic conditions enabled it, with the goal of identifying warning signs of explosive activity to improve long-term hazard planning for Hawai'i communities and visitors. Kīlauea is ranked as the highest-threat volcano in the U.S. due to the large population and visitor volume to Hawai'i Volcanoes National Park. While the volcano has produced mostly gentle lava flows over the past two centuries, Kīlauea's stratigraphy indicates that alternating explosive-effusive cycles may represent its typical long-term behavior.

Work is performed in Honolulu, Hawaii, with a period of performance from October 15, 2026, through September 30, 2028.

Abstract

K?lauea, on the island of hawai?I, is one of the most active volcanoes on earth. The volcano is ranked as the highest-threat volcano in the U.S. Because of the large population and large number of visitors to hawai?I volcanoes national park. For the past two centuries, K?lauea has produced mostly gentle lava flows. However, long periods of explosive, ASH-producing eruptions have also occurred. Explosive eruptions may be part of the volcano?S normal behavior rather than a rare exception. Only the two most recent explosive periods of the last 2,500 years have been studied in detail. Scientists do not yet understand what triggers the shifts between quiet and explosive activity. This project will investigate a 10,000-year-long explosive episode known as the pahala tephra. Research will determine when the episode occurred and what conditions inside the volcano allowed IT to happen. This research will help scientists recognize warning signs of explosive activity. Results will improve long-term hazard planning for hawai?I communities and visitors. This project investigates the origins, duration, and spatial distribution of the pahala tephra, a proposed ~10,000-year-long explosive eruptive cycle of K?lauea volcano. The ASH and pyroclastic deposits were emplaced between approximately 30,000 to 3,500 years ago. K?lauea?S stratigraphy indicates that alternating explosive-effusive cycles may represent the volcano?S typical long-term behavior, rather than the sustained effusive activity observed over the last two centuries. However, only the two most recent explosive cycles in the last 2,500 years have been characterized in detail. The investigators will use a multidisciplinary approach that combines field stratigraphic and dispersal mapping of tephra units; radiocarbon dating of intercalated charcoal to constrain eruption timing and cycle duration; textural analysis of pyroclast groundmass and vesicles to estimate magma decompression rates; and geochemical analysis of volatile contents, degassing state, and mantle source characteristics. Results will be used to reconstruct the magma storage and supply configuration that were active during the pahala period. Comparison of these deposits with the overlying and underlying effusive units will test whether explosive activity is driven primarily by elevated magmatic volatile content or requires interaction between rising magma and groundwater within a deep summit caldera. By identifying recurring physical and geochemical indicators associated with the onset, duration, and cessation of explosive cycles, this project will help establish the mechanisms that govern transitions between explosive and effusive behavior at K?lauea and provide a basis for assessing the likelihood and character of future long-lived explosive activity. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the foundation's intellectual merit and broader impacts review criteria.- subawards are not planned for this award.