Seismic Swarm VS20240622.1: Analysis of Recent Activity Near Volcano, Hawaii
A seismic swarm designated VS20240622.1 was recorded southwest of Volcano, Hawaii, beginning at 20:28 on 21 June 2024 and concluding at 00:08 on 20 July 2024. Over 675 hours and 40 minutes, the event sequence included 902 earthquakes, concentrated in an area known for frequent magmatic and tectonic unrest.
The swarm's initial phase, captured in the first 100 events through 27 June, featured predominantly low-magnitude activity. Events ranged from magnitude 0.4 to 3.0, with most registering between 1.7 and 2.6. Depths clustered near the surface, frequently at 0–2 km, though several reached 28–29 km, indicating both shallow crustal adjustments and deeper processes. Notable early shocks included a magnitude 2.6 at 00:55 on 22 June and a pair of events at magnitude 2.5 and 1.9 on 22 June at 18:48, both at greater depth. Subsequent activity maintained a pattern of brief clusters separated by quieter intervals, with magnitudes rarely exceeding 2.5.
This sequence aligns with Hawaii's established volcanic setting. The Island of Hawaii sits above a mantle hotspot that has generated the Hawaiian-Emperor seamount chain over millions of years. Shield volcanoes, built by successive basaltic lava flows, dominate the landscape. Kilauea, located immediately east of the swarm epicenter, remains one of the world's most active volcanoes, with documented eruptions spanning centuries. Magma movement through rift zones and shallow reservoirs commonly produces earthquake swarms as rock fractures under stress.
Historical records show 109 swarms in the region since 2000. Annual counts have varied, with elevated activity in 2023 (21 swarms) and 2020 (13 swarms). Earlier peaks occurred in 2018 (9 swarms) and 2003 (8 swarms). These episodes reflect ongoing adjustments within the volcanic system, often preceding or accompanying surface deformation and lava outbreaks.
The 2024 swarm's duration and event total fall within the typical range observed during periods of heightened unrest at Kilauea. Shallow events likely correspond to brittle failure above intruding magma, while deeper occurrences may trace fluid migration or pressure changes at the base of the volcanic edifice. No immediate surface eruption followed the swarm's termination, consistent with many prior sequences that dissipate without breakout.
Continued monitoring by the Hawaiian Volcano Observatory remains essential. Integration of seismic, geodetic, and gas data provides the clearest picture of subsurface dynamics and informs hazard assessments for nearby communities.
References SeismoSight internal classification records for swarm VS20240622.1 USGS Hawaiian Volcano Observatory summaries on Kilauea activity and regional tectonics