Timescales of cumulate mobilization and mixing for the 1868 A.D. eruption of Mauna Loa, Island of Hawai‘i
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Abstract
The deadly 1868 A.D. eruption of Mauna Loa’s lower Southwest Rift Zone (Island of Hawai‘i) included a M7.9 earthquake and associated tsunami and landslides, demonstrating the severe hazards posed by Earth’s largest active subaerial volcano. To better understand the relationship between intense seismic activity, dike emplacement, magma storage, transport histories, and mobilization of olivine cumulates at Mauna Loa, we examine compositional zoning of olivine in the 1868 lava flows. Samples range from basalt (< 10% olivine) to picrite (30–40% olivine). The olivine cargo is heterogeneous (Fo78.2–89.2; forsterite = [Mg/(Mg + Fe) × 100]) but dominated by ~ Fo89 cores that lie above the Fe-Mg equilibrium field of host glasses. Crystal rims < Fo80 are due to post-eruptive modification in slow cooling lava flows. Minor element compositions fall within the range of other Mauna Loa olivine erupted in the past 200 years. Olivine crystals exhibit both normal and complex Fo zoning patterns that yield timescales of diffusive re-equilibration that range from 3 to 258 days, with 72% of crystals recording 71 days or less. These timescales correspond to magmatic priming of the summit reservoir system ~ 2 months prior to the eruption and the M7.9 earthquake likely facilitated the transport of the crystal-rich summit-derived magmas downrift shortly prior to eruption. If the recently proposed faster Fe-Mg diffusion coefficient is used, timescales instead range from < 1 day to 25 days, with most recording 1 week or less. In this scenario, most of the olivine zoning would have to have been generated after the M7.9 earthquake perturbed the system.
Suggested Citation
Lynn, K.J., Schleicher, J., Bergantz, G.W., Shea, T., and Trusdell, F., 2026, Timescales of cumulate mobilization and mixing for the 1868 A.D. eruption of Mauna Loa, Island of Hawai‘i: Bulletin of Volcanology, v. 88, 84, 21 p., https://doi.org/10.1007/s00445-026-02008-1.
Study Area
| Publication type | Article |
|---|---|
| Publication Subtype | Journal Article |
| Title | Timescales of cumulate mobilization and mixing for the 1868 A.D. eruption of Mauna Loa, Island of Hawai‘i |
| Series title | Bulletin of Volcanology |
| DOI | 10.1007/s00445-026-02008-1 |
| Volume | 88 |
| Publication Date | July 08, 2026 |
| Year Published | 2026 |
| Language | English |
| Publisher | Springer |
| Contributing office(s) | Volcano Science Center |
| Description | 84, 21 p. |
| Country | United States |
| State | Hawaii |
| Other Geospatial | Mauna Loa |