Seismic Swarm VS20240425.1: Analysis of Activity Southwest of Volcano, Hawaii

Seismic swarm VS20240425.1 was recorded 7 km southwest of Volcano, Hawaii, beginning at 11:29 on 24 April 2024 and concluding at 22:21 on 11 May 2024. Over 418 hours and 51 minutes, the sequence produced 864 earthquakes. This event aligns with patterns of volcanic seismicity common to the Island of Hawaii, where magma movement beneath active shield volcanoes generates frequent earthquake swarms.

The region lies within the Hawaii hotspot province, characterized by basaltic volcanism from the Hawaiian-Emperor seamount chain. Volcano, Hawaii, sits adjacent to Kilauea volcano, whose East Rift Zone and summit caldera have produced repeated seismic episodes linked to magma intrusion and flank movement. Depths in the swarm data cluster at shallow levels (0–2 km), consistent with crustal processes above the volcanic conduits, while isolated events reached 23 km, reflecting deeper tectonic adjustments along the volcanic flank.

Examination of the first 100 events reveals a predominance of low-magnitude earthquakes. Magnitudes ranged from 1.1 to 2.8, with the majority falling between 1.3 and 2.4. Depths were overwhelmingly shallow, concentrated at 0–2 km, and only a few registered at greater depths early in the sequence. Timing shows clustered activity on 24–27 April, with repeated pairs of similar-magnitude events minutes apart, a hallmark of swarm behavior driven by fluid migration rather than mainshock-aftershock sequences.

Hawaii has experienced 100 documented swarms since 1 January 2000. Yearly counts indicate variability, with elevated activity in 2023 (20 swarms), 2020 (10), and 2018 (9). Earlier years such as 2003 (8) and 2021 (7) also contributed notably. This distribution underscores the persistent volcanic unrest in the area, where swarms often precede or accompany eruptive phases at Kilauea or Mauna Loa.

The VS20240425.1 swarm fits within this long-term framework, illustrating ongoing adjustments in the volcanic system. Shallow focal depths and moderate magnitudes point to localized stress release associated with magma or hydrothermal fluid movement. Continued monitoring remains essential for assessing any escalation toward surface deformation or eruptive activity.

References

USGS Hawaiian Volcano Observatory seismic catalogs and reports on Kilauea activity.
Hawaii Volcanoes National Park geological summaries on hotspot volcanism.
SeismoSight internal swarm classification records for VS20240425.1 parameters and historical counts.