Pahala, Hawaii – Despite the absence of an eruption, the USGS Volcano Alert Level for Kilauea remains at ADVISORY. Even though no eruption is currently taking place, there is ongoing unrest beneath Halema’uma’u, the southern caldera, and the upper East Rift Zone. This unrest has been characterized by an increase in the number of earthquakes below the summit and upper East Rift Zone since Friday night.
The USGS Hawaiian Volcano Observatory emphasized the unpredictability of the situation, stating that it is unclear whether the rise in activity will result in an intrusion or eruption soon, or if it will continue as seismic unrest at depth. Changes in the nature and location of unrest can happen rapidly, as can the potential for an eruption. Despite the current focus on the explosive activity that occurred a century ago, new discoveries are being made by studying the ash deposits from the 1924 eruptions of Kilauea.
Detailed field and laboratory studies conducted by USGS Hawaiian Volcano Observatory geologists have provided insights into the layers of ash deposited during the 1924 explosions. The analysis of the ash samples revealed a significant amount of recycled material, supporting the traditional interpretation that the eruptions were driven by water-rock interactions, known as phreatic explosions. However, recent findings have shown that some of the youngest layers in the 1924 deposits contain fresh magma, challenging the classic explanation of the explosions being steam-driven.
Collaboration between HVO scientists and researchers at the University of Hawaii at Manoa has allowed for a deeper understanding of the magma involved in the 1924 explosions. Through the use of various analytical techniques, the composition and textures of the juvenile material from 1924 have been examined. The identification of different chemical groups within the ash deposits suggests the involvement of multiple magmas during the explosive eruptions.
The variations in chemical composition and textures of the ash grains from the 1924 deposits indicate the presence of at least three different magma types, potentially explaining the explosive nature of the eruptions. Furthermore, the discovery of olivine crystals in the juvenile component of the eruptions provides additional insights into the complex interactions that took place beneath Halema’uma’u. The ongoing research aims to unravel the mysteries surrounding the 1924 eruptions and shed light on the processes that led to the explosive events.
As we commemorate the 100th anniversary of the 1924 explosive eruptions at Kilauea, the scientific community is only beginning to uncover the secrets hidden within the ash deposits. The quest to understand how different magmas interacted, the timeline leading up to the explosions, and the factors triggering the eruptions continues through dedicated research efforts. By delving deeper into the deposits from a century ago, scientists hope to gain valuable insights into the volcanic processes at play and their implications for future volcanic activity.