Seismic Swarm VS20231229.1: Analysis of Activity Near Volcano, Hawaii

A seismic swarm designated VS20231229.1 was recorded 8 km southwest of Volcano, Hawaii, beginning at 01:15 on 28 December 2023 and concluding at 21:46 on 1 January 2024. Over 116 hours and 30 minutes, the swarm comprised 173 earthquakes. This event aligns with the region's established pattern of volcanic seismicity driven by magma movement beneath the Kilauea volcano system.

Analysis of the first 100 events reveals a concentration of low-magnitude activity. Magnitudes ranged primarily from 0.4 to 2.9, with the majority falling between 1.0 and 2.0. Depths were shallow, mostly between 0 and 4 km, though a few reached up to 11 km. Early events on 28 December included isolated higher magnitudes such as 2.9 at 7 km depth, followed by clusters of smaller quakes at depths of 1 km or less. Subsequent days showed sustained low-level activity with occasional peaks at 2.5, often at depths around 1-2 km. This distribution indicates typical swarm characteristics associated with fluid migration in volcanic crust rather than a single large rupture.

The Island of Hawaii lies within a tectonically active zone shaped by the Hawaiian hotspot. Kilauea, one of the world's most active volcanoes, produces frequent earthquake swarms as magma ascends through rift zones and shallow reservoirs. Historical records confirm 109 such swarms since 1 January 2000, with annual counts varying from 1 to 21. Recent years have shown elevated frequency, including 21 swarms in 2023 alone. These events reflect ongoing volcanic unrest without necessarily preceding major eruptions.

Geological context emphasizes the shield volcano structure of Kilauea, built from successive basaltic lava flows. Seismic swarms commonly occur along the East Rift Zone and south flank, influenced by gravitational spreading and magmatic pressure. Depths under 10 km align with the shallow plumbing system feeding surface vents.

This swarm's parameters fit established patterns observed in prior episodes, underscoring the value of continuous monitoring for hazard assessment in populated areas near Hawaii Volcanoes National Park.

References

USGS Hawaiian Volcano Observatory reports on Kilauea seismicity (updated through 2024).
Hawaii Volcanoes National Park geological summaries.
SeismoSight internal swarm classification data for VS20231229.1.