Seismic Swarm S20240817.1 Near Kilauea Volcano, Hawaii

Seismic swarm S20240817.1 was recorded 7 km south-southeast of Volcano, Hawaii, on the Big Island. The sequence began at 05:57 on 16 August 2024 and concluded at 13:30 on 10 September 2024, spanning 607 hours and 32 minutes. During this interval, 751 earthquakes were detected.

The swarm occurred within the seismically active zone associated with Kilauea volcano. Kilauea, one of the world’s most active shield volcanoes, sits above the Hawaiian hotspot and has exhibited persistent eruptive and intrusive activity for centuries. Its southern flank experiences frequent earthquake swarms linked to magma migration, dike intrusions, and gravitational adjustments along the Hilina fault system. Depths in the reported events remained predominantly shallow, between 0 and 9 km, consistent with processes occurring within or immediately beneath the volcanic edifice.

Analysis of the first 100 events reveals a rapid onset followed by sustained low-to-moderate magnitude seismicity. Magnitudes ranged from 0.5 to 3.0, with the majority falling between 1.5 and 2.5. The largest event reached magnitude 3.0 on 16 August at 23:34. Depths clustered near 1–2 km, though several events occurred at 0 km or as deep as 9 km. Temporal distribution showed clusters of activity, particularly on 16–17 August and again on 19–20 August, with many events separated by minutes. This pattern is typical of volcanic swarms where fluid pressure or magma movement triggers repeated brittle failure along pre-existing fractures.

Historical records maintained by SeismoSight document 107 swarms in the same region since 1 January 2000. Annual counts vary considerably: three swarms occurred in 2000, one in 2001, eight in 2003, four in 2004, one in 2005, two in 2006, four in 2007, one in 2008, four in 2011, four in 2012, one in 2013, two in 2014, three in 2015, two in 2016, two in 2017, nine in 2018, three in 2019, eleven in 2020, seven in 2021, six in 2022, twenty-one in 2023, and eight in 2024 prior to the current sequence. Elevated swarm frequency in 2018, 2020, and 2023 correlates with documented eruptive episodes and intrusive events at Kilauea.

Such swarms contribute to ongoing monitoring of volcanic unrest. The Hawaiian Volcano Observatory integrates seismic data with deformation measurements and gas emissions to assess hazard levels. While most swarms do not culminate in eruption, they indicate active magmatic or tectonic processes that warrant continued surveillance.

References

• United States Geological Survey, Hawaiian Volcano Observatory – Kilauea activity summaries (2024)
• SeismoSight internal swarm catalogue (2000–2024)