Josephine Barnett Kendra J. Lynn Baylee R. McDade Kamalani Poepoe Meghann Decker Natalia I. Deligne 20250919 spreadsheet https://doi.org/10.5066/P13HD3LX The September 2023 Halema‘uma‘u eruption began on September 10 and ended on September 16 (~1 week; Mulliken et al. 2024). Field crews from the U.S. Geological Survey’s Hawaiian Volcano Observatory collected tephra samples from fissures that had opened up on an area of the caldera floor east of Halema‘uma‘u crater (see Lynn et al. 2024 for map). Air quenched spatter and tephra samples were collected from eight of the fissures that were accessible from the down-dropped block of the old caldera floor to the northeast of the active lake surface. Samples were collected from within a publicly closed area of Hawai‘i Volcanoes National Park in cooperation with the National Park Service. This data release provides olivine core and rim spot analyses from electron microprobe analytical work. The analyses were done on olivine crystals 0.5-2.0 mm in size picked from tephra samples (see Lynn et al. 2024 for additional sample and compositional information). Data were collected to characterize the compositions of olivine crystals in the September 2023 eruption of Halema‘uma‘u. 20231010 20231016 observed Complete None planned -155.29535 -155.25570 19.43211 19.39229 ISO 19115 Topic Category biota USGS Metadata Identifier USGS:68950163d4be0274c894cf84 None olivine September 2023 eruption tephra forsterite None Kilauea Island of Hawai‘i Kaluapele None. Please see 'Distribution Info' for details. None. Users are advised to read the dataset's metadata thoroughly to understand appropriate use and data limitations. Kendra J. Lynn U.S. Geological Survey Hawaiian Volcano Observatory Research Geologist mailing and physical

1266 Kamehameha Avenue Suite A8

Hilo Hawaii 96720 USA 808-936-6085 klynn@usgs.gov University of Hawai‘i at Hilo, Research Corporation of the University of Hawai‘i Methodology and details are outlined in accompanying docx file. Methodology and details are outlined in in accompanying docx file. This dataset includes olivine core and rim compositions for assessing olivine population characteristics for the September 2023 Halema‘uma‘u eruption of Kilauea. Methodology and details are outlined in accompanying docx file. 2024 The September 2023 Halema‘uma‘u eruption began on September 10 and ended on September 16 (~1 week; Mulliken et al. 2024). Field crews from the U.S. Geological Survey’s Hawaiian Volcano Observatory collected tephra samples from fissures that had opened up on an area of the caldera floor east of Halema‘uma‘u crater (see Lynn et al. 2024 for map). Air quenched spatter and tephra samples were collected from eight of the fissures that were accessible from the down-dropped block of the old caldera floor to the northeast of the active lake surface. Samples were collected from within a publicly closed area of Hawai‘i Volcanoes National Park in cooperation with the National Park Service. This data release provides olivine core and rim spot analyses from electron microprobe analytical work. The analyses were done on olivine crystals 0.5-2.0 mm in size picked from tephra samples (see Lynn et al. 2024 for additional sample and compositional information). Barnett, J., Lynn, K.J., McDade, B.R., Decker, M., Poepoe, K.K., Deligne, N.I. (2025) Olivine core and rim electron microprobe analyses for the September 2023 Halema‘uma‘u eruption of Kīlauea, Island of Hawai‘i. U.S. Geological Survey data release, https://doi.org/10.5066/P13HD3LX. GS ScienceBase U.S. Geological Survey mailing address

Denver Federal Center, Building 810, Mail Stop 302

Denver CO 80225 United States 1-888-275-8747 sciencebase@usgs.gov Unless otherwise stated, all data, metadata and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S. Geological Survey (USGS), no warranty expressed or implied is made regarding the display or utility of the data on any other system or for general or scientific purposes, nor shall the act of distribution constitute any such warranty. Digital Data https://doi.org/10.5066/P13HD3LX None 20250919 Kendra J. Lynn U.S. Geological Survey Hawaiian Volcano Observatory Research Geologist mailing and physical

1266 Kamehameha Avenue Suite A8

Hilo Hawaii 96720 USA 808-936-6085 klynn@usgs.gov FGDC Content Standard for Digital Geospatial Metadata FGDC-STD-001-1998