New Discoveries Unveiled in Ash Deposits from Kilauea’s 1924 Explosive Eruptions

Pahala, Hawaii – Though Kilauea Volcano on the Big Island is currently not erupting, the US Geological Survey has maintained the volcano’s alert level at ADVISORY. Despite the lack of activity on the surface, volcanic unrest persists underground beneath Halema’uma’u, the south caldera, and the upper East Rift Zone. This unrest has been marked by a recent uptick in earthquake activity starting Friday night, with seismic clusters observed below the summit and upper East Rift Zone.

The USGS Hawaiian Volcano Observatory emphasized that the recent increase in activity could potentially lead to an intrusion or eruption in the near future or could continue as seismic unrest at depth. Changes in the location and nature of volcanic unrest can happen rapidly, along with the possibility of an eruption occurring suddenly.

In a recent article titled “Volcano Watch,” HVO geologist Kendra J. Lynn and University of Hawai’i at Mānoa student Reed Mershon delved into the explosive activity that took place at Kilauea 100 years ago. The focus of the article was on the 1924 explosive eruptions and the impact they had on surrounding communities.

Geologists from the USGS Hawaiian Volcano Observatory have been studying the ash deposits left behind by the 1924 explosions, conducting detailed fieldwork and laboratory analyses to uncover new insights. The ash layers, which have largely remained undisturbed for a century, were examined around Halema’uma’u, revealing important information about the explosive events.

During the 1924 eruption, ash was distributed as far as Pāhala, with thickest deposits found within a 2-mile radius of Halema’uma’u. Analysis of the ash samples in the lab indicated the presence of both recycled lavas (lithic material) and fresh magma (juvenile material), suggesting a complex interaction of different materials during the explosive activity.

The researchers also discovered that some of the youngest ash layers from the 1924 eruptions contained up to 30% juvenile material, a finding that challenges the conventional understanding of the eruptions being driven solely by water-rock interactions. The collaboration between HVO scientists and colleagues from the University of Hawai’i at Mānoa has helped shed light on the compositions and textures of the magma involved in the explosions.

By examining the chemical compositions and textures of the ash deposits, researchers were able to identify distinct magma types associated with the 1924 explosive eruptions. The presence of olivine crystals with varying chemistry and textures further indicated the mixing of different magmas prior to and during the eruption, offering valuable insights into the volcanic processes at play during the explosive events.

Despite the passage of a century since the 1924 eruptions, scientists believe that there is still much to be learned from studying the deposits left by the explosions. The ongoing research aims to uncover the interactions between different magmas, the duration of magma storage in reservoirs, and the triggering mechanisms behind the explosive eruptions, providing a deeper understanding of volcanic activity at Kilauea.