Seismic Swarm VS20231005.1: Analysis of Activity Near Volcano, Hawaii

A seismic swarm designated VS20231005.1 was recorded southwest of Volcano, Hawaii, on the Big Island. The sequence began at 15:32 on 4 October 2023 and concluded at 13:50 on 12 October 2023. Over 190 hours and 17 minutes, 244 earthquakes were detected. Analysis of the first 100 events reveals predominantly low-magnitude activity, with values ranging from 0.1 to 2.6 and focal depths between 0 and 4 km. Most events clustered at depths of 1 km, consistent with shallow crustal processes in the region.

The swarm occurred in an area influenced by Kilauea volcano, one of Earth’s most active shield volcanoes. Kilauea lies within Hawaii Volcanoes National Park and forms part of the Hawaiian hotspot chain, where magma rises through the Pacific plate. Seismic swarms in this setting commonly result from magma intrusion, fluid migration, or stress changes along rift zones. Depths observed in the initial events align with typical shallow seismicity associated with the volcano’s east rift zone and summit caldera.

Historical records indicate frequent swarm activity in the vicinity. Since 1 January 2000, 96 swarms have been documented. Annual counts show variability, with notable increases in 2018 (9 swarms), 2020 (14 swarms), and 2021 (9 swarms). This pattern reflects ongoing volcanic and tectonic dynamics driven by the hotspot. Earlier periods, such as 2003 (8 swarms) and 2004 (5 swarms), also demonstrate recurrent episodes linked to eruptive cycles at Kilauea.

The 2023 swarm fits within a broader context of persistent low-level seismicity. Magnitudes remained below levels typically associated with significant structural damage, while the short duration and shallow depths suggest a localized source. Such events contribute to monitoring efforts that track magma movement and inform hazard assessments for nearby communities.

Geological studies of the Hawaiian Islands emphasize the role of the hotspot in generating both volcanic eruptions and associated seismicity. Kilauea’s history includes multiple summit and flank eruptions in recent decades, underscoring the need for continuous seismic surveillance. The VS20231005.1 sequence adds to the dataset used by researchers to model subsurface processes beneath the volcano.

References

• USGS Hawaiian Volcano Observatory reports on Kilauea seismicity
• Hawaii Volcanoes National Park geological summaries
• Peer-reviewed literature on Hawaiian hotspot tectonics (e.g., Journal of Volcanology and Geothermal Research)