Geology topics

Research about Mauna Loa volcano

Source-linked reports with geographic coverage including Mauna Loa volcano.

4 recordsLinked to original sources

USGS2025

Nodal seismic deployment on Mauna Loa volcano, Hawaii: Dataset and preliminary insights

Mauna Loa is the largest active volcano on Earth, comprising ∼51% of the Island of Hawai‘i’s landmass and posing significant risks to the island’s communities, infrastructure, and natural environment. Historical eruptions have produced lava flows that have reached the ocean in as little as 3 hr. The timing and location of such lava flows in the past 200 yr underscore how critical determination of the location and geometry of magma storage and structure is for volcanic hazard assessment and eruption forecasting. Now, after nearly 38 yr of volcanic quiescence, Mauna Loa has erupted again. On 27 November 2022, fissures initiated within the summit caldera and then migrated to the northeast rift zone, where they generated a large lava flow that threatened a major highway. To improve our understanding of the geometry of this magma system, we deployed a temporary nodal array on Mauna Loa in the summer of 2024. This increased our seismic coverage sufficiently to image this magmatic system. This nodal array consists of 33 seismometers distributed on and around the volcano and was deployed for over three months to record seismic signals. The primary objective of this project is to resolve the high‐resolution seismic velocity structure and characterize seismic features associated with magma storage and ascent pathways. In this article, we present an overview of the deployment, evaluate the quality of the data, and show example recordings to evaluate the suitability of the data set for future seismic investigations, including earthquake relocation, seismic tomography, and receiver function analysis. Comparisons with nearby permanent broadband and short‐period seismic stations demonstrate that the nodal array recorded high‐quality waveforms, making it a valuable resource for constraining the magmatic system beneath Mauna Loa at multiple scales.

Hawaii↗

USGS2019

The lava flow that came to Hilo—The 1880–81 eruption of Mauna Loa volcano, Island of Hawai‘i

The Mauna Loa eruption sequence of 1880–81 consists of two eruptions. The May 1880 eruption in Mokuʻāweoweo at the summit of Mauna Loa lasted just a few days and was followed 6 months later by three lava flows that issued from vents along the Northeast Rift Zone. The November 1880 eruption lasted almost a year and one of its flows nearly reached Hilo Bay. Public reaction in Hilo to the advancing lava flow increased as the lava got closer, but a smallpox quarantine prevented travelers and government officials from leaving Honolulu, the government seat of the Hawaiian Kingdom, until July 1881. In the King’s absence, his sister Princess Regent Liliʻuokalani and key officials met in Hilo at the beginning of August to plan a government response. This included the first known plan to use barriers and explosives to divert the lava flow in Hawaiʻi. Fortunately, the lava flow stopped before the plan was enacted; however, both Christian prayer and traditional Hawaiian chants and gifts to the Hawaiian deity Pele were offered in the last few weeks of lava activity. Mauna Loa was again restless in 2019 and the time seems optimum to review this and other Mauna Loa flows, in order to be ready for the next lava flow. Should the next flow threaten developed areas, review of past lava flow threats may provide valuable experience on how the public may best be provided with information.

Hawaii↗

USGS2018

Explosive eruptions at the summit of Mauna Loa: Lithology, modeling, and dating

Near Moku‘āweoweo, Mauna Loa’s summit caldera, there are three fans of explosive deposits. The fans, located to the west, northwest, and east, are strongly arcuate in map view. Along ‘Āinapō Trail, 2.8–3.5 km southeast of the caldera, there are several small kīpuka that expose a fourth explosive deposit. Although these explosive deposits have been known for some time, no study bearing on the nature of the explosive activity that formed them has been done. By analyzing cosmogenic exposure age data and the physical properties of the debris fans—lithology, size distributions, and clast dispersal—we conclude that the lithic deposits are the result of five separate phreatic events. The lithic ejecta consist of fragments of ponded lavas, pāhoehoe, gabbroic xenoliths, and “bread-crust” fragments. The exposure ages indicate that the explosive deposit on the west caldera rim was erupted 868 ± 57 yr B.P.; for the northwest fan, the age determination is 829 ± 51 yr B.P.; and on the east rim, ejecta deposits are younger, with ages of 150 ± 20 and 220 ± 20 yr B.P. Lavas underlying these deposits have exposure ages of 960–1020 yr B.P., consistent with the stratigraphy. Near ‘Āinapō Trail, the explosive deposit is much older, overlain by flows dated with a pooled mean age of 1507 ± 19 yr B.P. From the cosmogenic dating, we have three reliable and unambiguous dates. At a much earlier time, a fourth explosive eruption created the ‘Āinapō Trail deposit. We conclude there were at least five explosive episodes around the summit caldera. These deposits, along with recent work done on Kīlauea’s explosive activity, further discredit the notion that Hawaiian volcanoes are strictly effusive in nature. The evidence from the summit of Mauna Loa indicates that it, too, has erupted explosively in recent history.

Hawaii↗

USGS2006

Perspectives on basaltic magma crystallization and differentiation: Lava-lake blocks erupted at Mauna Loa volcano summit, Hawaii

Explosive eruptions at Mauna Loa summit ejected coarse-grained blocks (free of lava coatings) from Moku'aweoweo caldera. Most are gabbronorites and gabbros that have 0–26 vol.% olivine and 1–29 vol.% oikocrystic orthopyroxene. Some blocks are ferrogabbros and diorites with micrographic matrices, and diorite veins (≤2 cm) cross-cut some gabbronorites and gabbros. One block is an open-textured dunite. The MgO of the gabbronorites and gabbros ranges ∼ 7–21 wt.%. Those with MgO >10 wt.% have some incompatible-element abundances (Zr, Y, REE; positive Eu anomalies) lower than those in Mauna Loa lavas of comparable MgO; gabbros (MgO <10 wt.%) generally overlap lava compositions. Olivines range Fo 83–58 , clinopyroxenes have Mg#s ∼83–62, and orthopyroxene Mg#s are 84–63 — all evolved beyond the mineral-Mg#s of Mauna Loa lavas. Plagioclase is An 75–50 . Ferrogabbro and diorite blocks have ∼ 3–5 wt.% MgO (TiO 2 3.2–5.4%; K 2 O 0.8–1.3%; La 16–27 ppm), and a diorite vein is the most evolved (SiO 2 59%, K 2 O 1.5%, La 38 ppm). They have clinopyroxene Mg#s 67–46, and plagioclase An 57–40 . The open-textured dunite has olivine ∼ Fo 83.5 . Seven isotope ratios are 87 Sr/ 86 Sr 0.70394–0.70374 and 143 Nd/ 144 Nd 0.51293–0.51286, and identify the suite as belonging to the Mauna Loa system. Gabbronorites and gabbros originated in solidification zones of Moku'aweoweo lava lakes where they acquired orthocumulate textures and incompatible-element depletions. These features suggest deeper and slower cooling lakes than the lava lake paradigm, Kilauea Iki, which is basalt and picrite. Clinopyroxene geobarometry suggests crystallization at <1 kbar P. Highly evolved mineral Mg#s, <75, are largely explained by cumulus phases exposed to evolving intercumulus liquids causing compositional ‘shifts.’ Ferrogabbro and diorite represent segregation veins from differentiated intercumulus liquids filter pressed into rigid zones of cooling lakes. Clinopyroxene geobarometry suggests <300 bar P. Open-textured dunite represents olivine-melt mush, precursor to vertical olivine-rich bodies (as in Kilauea Iki). Its Fo 83.5 identifies the most primitive lake magma as ∼8.3 wt.% MgO. Mass balancing and MELTS show that such a magma could have yielded both ferrogabbro and diorite by ≥50% fractional crystallization, but under different fO 2 : < FMQ (250 bar) led to diorite, and FMQ (250 bar) yielded ferrogabbro. These segregation veins, documented as similar to those of Kilauea, testify to appreciable volumes of ‘rhyolitic’ liquid forming in oceanic environments. Namely, SiO 2 -rich veins are intrinsic to all shields that reached caldera stage to accommodate various-sized cooling, differentiating lava lakes.

Hawaii↗