Seismic Swarm VS20220107.1: Analysis Near Volcano, Hawaii

Seismic swarm VS20220107.1 occurred 6 km southwest of Volcano, Hawaii, on the Big Island. The sequence began at 23:34 on 6 January 2022 and concluded at 22:42 on 8 January 2022, spanning 47 hours and 8 minutes. During this period, 52 earthquakes were recorded, with magnitudes ranging from 0.6 to 2.4 and focal depths predominantly between 9 and 13 km.

The events clustered tightly in both space and time, a hallmark of swarm behavior driven by fluid migration or stress perturbations rather than a single mainshock-aftershock sequence. Most hypocenters aligned at approximately 10–11 km depth, consistent with the brittle-ductile transition zone beneath the Kīlauea volcanic edifice. Two notable outliers included a 2.4-magnitude event at 4 km depth and a 1.6-magnitude event at 28 km, the latter possibly reflecting deeper magmatic processes within the hotspot plumbing system.

This swarm fits within the long-term seismicity pattern of the region. Since 1 January 2000, 74 swarms have been documented in the immediate area, with notable yearly counts including 13 in 2020, 9 in 2018, 8 in 2003, and 7 in 2021. These episodes commonly accompany magma movement beneath Kīlauea, one of the world’s most active volcanoes situated above the Hawaiian mantle plume.

Geologically, the southwest flank of Kīlauea experiences frequent earthquake swarms due to dike intrusions, caldera subsidence, and interaction between the volcanic pile and the underlying oceanic crust. Depths around 10 km correspond to the level where magma accumulates before ascending or laterally propagating. Historical swarms have preceded or accompanied eruptive phases, although the 2022 event produced no surface activity.

The provided event catalog shows a gradual increase in activity on 7 January, peaking midday before tapering overnight into 8 January. Magnitudes remained modest, with only three events exceeding magnitude 1.9, underscoring the low-energy character typical of volcanic swarms in this setting.

References:
USGS Earthquake Catalog (earthquake.usgs.gov)
Hawaiian Volcano Observatory reports on Kīlauea seismicity
Global Volcanism Program, Smithsonian Institution
SeismoSight internal swarm classification VS20220107.1