Table 1 Characteristics of sampled eruptive products from the volcanoes of Mauna Loa and Kīlauea used for this study, ordered from youngest to oldest

Halemaʻumaʻu, June 2023 (Kīlauea)

Reticulite from opening eruptive phase of the June 2023 Halemaʻumaʻu eruption. Sampled at Kīlauea’s summit during the first day of the eruption, during deposition

Lava lake and fountaining eruption within Halemaʻumaʻu Crater. The first lava fountain reached a height of ~ 100 m. Later, other vents opened that produced fountains up to ~ 10 m high

June 7, 2023

Halemaʻumaʻu, September 2021 (Kīlauea)

Reticulite sampled at Kīlauea’s summit during the 2021 Halemaʻumaʻu eruption

Lava lake and fountaining eruption within Halemaʻumaʻu Crater. The highest lava fountain sustained a height of 20–25 m throughout the first night

September 29, 2021

Puʻupuaʻi surface (Kīlauea)

Tephra deposit that formed the Puʻupuaʻi tephra cone. Fluidal to pumiceous pyroclast textures (Stovall et al. 2011). Pyroclasts were picked from the deposit surface

High lava fountaining eruption of Kīlauea Iki (Richter et al. 1970)

November 15, 1959

Puʻupuaʻi (Kīlauea)

The same Puʻupuaʻi tephra deposit, but pyroclasts were picked from the subsurface

High lava fountaining eruption of Kīlauea Iki (Richter et al. 1970)

November 15, 1959

Mauna Loa 1949

Pumice deposit surrounding scoria cone on SSW rim of Mokuʻāweoweo caldera at the summit of Mauna Loa volcano (Macdonald and Orr 1950)

Large effusive eruption with lava fountaining

January 6, 1949

Keanakākoʻi Tephra (Kīlauea)

 Unit K2

Thin pumice airfall deposit overlying K1, previously known as the “eastern pumice”. K1 and K2 are similar in appearance but differ chemically (Garcia et al. 2018). The lower part of K2 consists mostly of Pele’s hair and tears, whereas the upper part contains pumice lapilli. The latter were sampled for this study

Lava fountaining event, erupted from the east side of Kaluapele (Swanson and Houghton 2018)

after 1823 CE

 Unit K1

Pumice deposit, previously named the “golden pumice” (Sharp et al. 1987) after its gold-like color

High lava fountaining sequence (Biass et al. 2018)

between 1790 and 1823 CE

 Unit E

Well-sorted scoria airfall deposit

Subplinian eruption (Swanson and Houghton 2018)

 ~ 1650 CE

 Unit D

Fine to medium-grained ash, containing glassy pyroclasts that are mostly dense and blocky (Swanson and Houghton 2018; Schmith and Swanson 2023). Sampled pyroclasts are pumice lapilli of 2–3 cm diameter

Series of weak phreatomagmatic eruptions (Swanson and Houghton 2018; Schmith and Swanson 2023)

16th to early seventeenth century

 Unit B

Reticulite bed surrounding Kīlauea Crater

Series of high (> 600 m) lava fountaining events (May et al. 2015)

 ~ 1500 CE