Seismic Swarm VS20050125.1: Analysis of Activity Near Kilauea Volcano, Hawaii

A notable earthquake swarm, designated VS20050125.1, occurred 7 km SSW of Volcano, Hawaii, on the Big Island. The sequence began at 18:24 on 24 January 2005 and concluded at 17:51 on 9 February 2005, spanning 383 hours and 27 minutes. During this period, 208 earthquakes were recorded. This swarm reflects typical seismic patterns associated with magma movement beneath Kilauea, one of the world's most active shield volcanoes.

Kilauea forms part of the Hawaiian hotspot chain, where the Pacific Plate moves over a mantle plume, generating basaltic volcanism. The volcano's summit and rift zones experience frequent seismicity due to dike intrusions, pressure changes in the magma reservoir, and faulting along the south flank. Depths in this swarm ranged from negative values (indicating surface or very shallow events) to 10 km, consistent with activity in the volcanic edifice and upper crust. Magnitudes remained modest, peaking at 2.8, which aligns with non-eruptive swarms that often precede or accompany minor adjustments in the magmatic system.

Analysis of the first 100 events reveals a clear temporal evolution. Initial activity on 24–25 January featured predominantly shallow events at depths of 0–3 km, with magnitudes between 1.0 and 2.0. A cluster of events around midday on 25 January included several magnitude 2.0 shocks at depths near 0–2 km, culminating in the swarm's largest event of magnitude 2.8 at 2 km depth. Subsequent events on 26 January shifted toward greater depths of 4–10 km, with magnitudes mostly 1.1–2.4. This deepening suggests migration of stress or fluid along deeper pathways beneath the volcano. Later events through 27 January maintained a mix of shallow and intermediate depths, with magnitudes rarely exceeding 2.0.

Such patterns are characteristic of Kilauea's long-term behavior. The region has hosted multiple swarms linked to episodic magma supply from the hotspot. Historical records since 1 January 2000 document 17 swarms in total, distributed as follows: three in 2000, one in 2001, eight in 2003, and five in 2004. These sequences underscore the persistent volcanic dynamism of the area, driven by continuous magma ascent and lateral transport along rift zones.

Overall, swarm VS20050125.1 exemplifies the background seismic unrest that defines Kilauea's geological setting. Continued monitoring remains essential for understanding potential transitions to eruptive phases in this highly active volcanic environment.

References

USGS Hawaiian Volcano Observatory reports on Kilauea seismicity.
Hawaii Volcanoes National Park geological summaries.
Pacific Tsunami Warning Center historical earthquake data.