Seismic Swarm VS20240127.1: Analysis of Activity Southwest of Volcano, Hawaii

An earthquake swarm designated VS20240127.1 was recorded 7 km southwest of Volcano, Hawaii, on the Big Island. The sequence began at 19:00 on 27 January 2024 and concluded at 04:19 on 27 February 2024, spanning 729 hours and 19 minutes. During this interval, 1,836 earthquakes were detected, consistent with patterns of shallow volcanic seismicity driven by magma movement beneath the Kīlauea volcanic system.

The Hawaiian Islands form through hotspot volcanism, where the Pacific plate moves over a mantle plume, producing shield volcanoes such as Kīlauea. This region experiences frequent seismic swarms due to the interaction between rising magma, groundwater, and tectonic stresses along rift zones. Depths typically remain under 5 km, reflecting brittle failure in the volcanic edifice rather than deeper tectonic events.

Analysis of the first 100 events reveals predominantly low-magnitude activity. Magnitudes ranged from 0.2 to 3.0, with the majority between 1.0 and 2.5. Depths clustered at 0–2 km, indicating very shallow sources aligned with the upper volcanic crust. Temporal distribution showed initial clustering on 27 January, including events of 2.6, 3.0, and 2.5, followed by sustained lower-energy releases through 28 January. No single dominant mainshock occurred; instead, the sequence exhibited swarm-like characteristics with multiple events of similar size.

Historical records since 2000 document 104 swarms in the area. Annual counts demonstrate variability, with notable increases in 2018 (8 swarms), 2020 (14), 2021 (11), 2022 (7), and 2023 (22). Earlier decades recorded fewer episodes, such as 6 in 2003 and 2004. This trend aligns with ongoing eruptive cycles at Kīlauea, where magma intrusion periodically triggers elevated seismicity along the Southwest Rift Zone.

The 2024 swarm fits within established patterns of unrest near Volcano, where shallow seismicity often precedes or accompanies surface deformation and gas emissions. Depths and magnitudes remain consistent with prior episodes, underscoring the persistent influence of magmatic processes in this tectonically active volcanic setting.

References

United States Geological Survey, Hawaiian Volcano Observatory reports on Kīlauea seismicity.
Global Volcanism Program, Smithsonian Institution, Hawaii volcano summaries.
SeismoSight internal swarm classification database.