Seismic Swarm VS20170305.1: Analysis Near Volcano, Hawaii

The seismic swarm designated VS20170305.1 occurred 7 km south of Volcano on Hawaii's Big Island. It began at 21:19 on 4 March 2017 and concluded at 07:40 on 7 March 2017, spanning 58 hours and 20 minutes. During this interval, 48 earthquakes were recorded. The events clustered at shallow depths, predominantly between 0 and 5 km, consistent with volcanic and tectonic processes in the region. Magnitudes ranged from 0.4 to 3.8, with the largest events occurring on 5 March between 16:13 and 16:17 UTC.

Geologically, this area lies on the flank of Kilauea volcano, one of Earth's most active shield volcanoes. The Hawaiian Islands form above a mantle hotspot, where magma ascent drives both eruptive activity and associated seismicity. Earthquake swarms in this setting commonly result from magma movement, dike intrusion, or stress changes along rift zones and fault systems such as the Hilina and Koa'e faults. Depths recorded in the swarm align with typical patterns for Kilauea-related activity, where shallow crustal earthquakes reflect brittle failure above the shallow magma reservoir.

Historical data indicate that seismic swarms have been recurrent in the Volcano region. Since 1 January 2000, 41 such swarms have been documented. Yearly counts show elevated activity in certain periods, including eight swarms in 2003, five in 2004, and four each in 2007, 2011, and 2012. This frequency underscores the persistent volcanic-tectonic environment around Kilauea, where swarms often precede or accompany changes in eruptive behavior.

Analysis of the 2017 swarm reveals a temporal concentration of stronger events on 5 March, when multiple magnitude 3+ earthquakes occurred within minutes. Most events remained below magnitude 2.0, indicating a swarm dominated by smaller releases rather than a single mainshock-aftershock sequence. One outlier event at 34 km depth suggests possible deeper magmatic or tectonic involvement, though the majority of activity stayed within the upper 5 km. Such patterns are characteristic of fluid migration or pressure changes within the volcanic edifice.

The swarm's location and timing fit within the broader framework of Kilauea's south flank dynamics, where gravitational spreading and magma pressure interact. No surface rupture or significant deformation was associated with this particular episode based on available monitoring records. Continued seismic monitoring by the Hawaiian Volcano Observatory helps contextualize these events within long-term volcanic cycles.

References

USGS Earthquake Catalog
Hawaiian Volcano Observatory Annual Summaries
Smithsonian Global Volcanism Program – Kilauea reports