Mantle controls on magmatic-volcanic cycles at basaltic volcanoes: An isotopic probe of the Pu'u 'O'o, Halema'uma'u, and 2018 Leilani eruptions of Kilauea Volcano

University Of Hawaii, Honolulu

Investigators

Abstract

The spectacular 2018 Leilani rift eruption of Kilauea Volcano captivated the attention of nightly news-watchers and internet-surfers around the U.S. and the world, and it became a destructive volcanic crisis for residents of the Island of Hawaii. The volcanic events of 2018 included the end of two sustained lava eruptions at Kilauea, a large (magnitude 6.9) local earthquake, and a voluminous (~0.8 km3) explosive collapse of the volcano’s summit region that damaged roads and infrastructure in Hawaii Volcanoes National Park. Over three months in 2018, a large amount of new lava (>0.8 km3) erupted from fissures on Kilauea’s Lower East Rift Zone at Leilani Estates and destroyed ~700 homes. The scale of this eruption (i.e., its high effusion rate and level of destruction) was “truly unprecedented in the modern record” according to Tina Neal, the Scientist-in-Charge at the Hawaiian Volcano Observatory of the U.S. Geological Survey. Very little is yet known about the magmatic processes that controlled the volcanic events of 2018. In this study, the temporal changes in the composition of lava samples from three Kilauea eruptions, each separated by ~20 km, will be used to track the movement of magma batches through the volcano’s plumbing system as a function of time and space. These results will be used to test the hypothesis that the 2018 Leilani rift eruption was actively driven by the delivery of at least one large mantle-derived magma batch to a volcanic edifice that already held an unusually large amount of stored magma. This research has the potential to reveal the enigmatic mantle controls on the behavior and hazards of Kilauea Volcano. An educational module, simulating the volcanic events at Kilauea in 2018 through role playing, will be created and published on the Science Education Resource Center (SERC) website for Hawaiian Volcanoes and Hazards Education as an integral part of this study. Kilauea experiences long-term cycles of dominantly effusive vs. explosive volcanic activity on a time scale of decades to centuries, with the latter often associated with summit collapse and/or caldera formation. The events of 2018 likely mark the culmination of a volcanic cycle at Kilauea. Lavas from this volcano display systematic chemical (e.g., Nb/Y) and isotopic (e.g., 206Pb/204Pb) variations on time scales of years to centuries due to its mantle source heterogeneity and melting processes. These mantle-derived changes in parental magma composition indicate that Kilauea also experiences distinctive magmatic cycles, some of which coincide with the long-term volcanic cycles. An important project goal is to test the idea that the long-term volcanic cycles at Kilauea are ultimately driven by mantle processes, including (1) the generation of compositionally distinct magma batches within the heterogeneous mantle and (2) the transport of these magma batches from the source to the surface. Kilauea’s magmatic-volcanic cycles may be caused by two mechanisms. One mechanism—essentially passive—is related to a refractory mantle source-related decrease in the degree of partial melting, a decline in the magma supply rate, and a subsequent disruption of the summit magmatic plumbing system. This was important for the previous magmatic-volcanic cycle that ended with summit collapse and an explosive eruption in 1924. The other mechanism—actively driven—is related to high degrees of partial melting of a more fertile mantle source, a high rate of magma supply, and the vigorous delivery of one or more large magma batches from the mantle. This hypothesis for the events of 2018 will be tested using the chemistry and Pb, Sr, and Nd isotope ratios of lava samples from (1) the 2018 Leilani rift eruption, and (2) the final decade of the long-lived Pu’u ’O’o rift eruption (1983-2018) and summit lava lake within Halema’uma’u Crater (2008-2018). 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.