Seismic Swarm VS20241214.1: Analysis of Activity Near Volcano, Hawaii

Seismic swarm VS20241214.1 was recorded southwest of Volcano, Hawaii, on the Big Island. The sequence began at 21:43 on 13 December 2024 and concluded at 06:28 on 21 December 2024, spanning 176 hours and 45 minutes. During this period, 90 earthquakes were detected, with magnitudes ranging from 0.4 to 3.2 and depths primarily between 0 and 29 km.

The events clustered in a compact area 7 km southwest of Volcano, consistent with the volcanic and tectonic setting of Kilauea’s southern flank. Most earthquakes occurred at shallow depths of 0–2 km, indicating possible involvement of shallow magmatic or hydrothermal processes. A smaller number of deeper events, reaching 28–29 km, suggest involvement of the deeper crustal plumbing system beneath the volcano.

Magnitude distribution showed a predominance of events between 1.5 and 2.5, with the largest shock reaching 3.2 on 18 December. The swarm exhibited typical characteristics of volcanic seismicity: relatively low magnitudes, high event rates over several days, and a lack of a single dominant mainshock. Activity peaked between 14 and 18 December before gradually declining toward the end of the sequence.

The region lies within the Hawaii hotspot province, where the Pacific Plate moves over a mantle plume, sustaining persistent volcanism at Kilauea. This volcano has produced repeated seismic swarms throughout recorded history, often preceding or accompanying eruptive episodes. Since 2000, 115 swarms have been documented in the area, with notable increases in frequency during 2018 (10 swarms), 2020 (12 swarms), 2023 (21 swarms), and 2024 (13 swarms to date). These patterns reflect ongoing adjustments in the volcanic system driven by magma movement and flank instability.

Kilauea’s geology features a summit caldera, rift zones, and mobile south flank that slides seaward along a basal detachment fault. Seismic swarms commonly occur along these structures as magma intrudes or as the flank responds to gravitational forces. Depths recorded in the current swarm align with both shallow rift-zone processes and deeper events near the décollement.

The December 2024 swarm did not culminate in an eruption, consistent with many past episodes that dissipate without surface activity. Continued monitoring remains essential given the volcano’s history of rapid changes in unrest.

References
SeismoSight internal swarm classification VS20241214.1
USGS Hawaiian Volcano Observatory earthquake catalog (historical swarm statistics since 2000)
USGS geologic framework reports on Kilauea volcano and the Hawaii hotspot.