Seismic Swarm S20240912.1: Analysis of Recent Activity Near Kilauea Volcano, Hawaii

A significant seismic swarm, designated S20240912.1, was recorded 10 km southeast of Volcano, Hawaii, highlighting the ongoing tectonic and volcanic dynamics of the region. The swarm initiated at 02:01 on 11 September 2024 and concluded at 14:09 on 24 September 2024, encompassing 711 earthquakes over 324 hours and 7 minutes. This event aligns with patterns of seismicity driven by magma movement beneath the active Kilauea shield volcano.

Kilauea, situated on the Big Island of Hawaii, forms part of the Hawaiian-Emperor seamount chain resulting from the Pacific Plate's movement over a mantle hotspot. The volcano's summit and rift zones experience frequent seismic swarms due to the intrusion of magma through the crust. Depths of recorded events in this swarm predominantly ranged from 0 to 7 km, consistent with shallow crustal processes associated with volcanic unrest, though occasional deeper events up to 29 km suggest interactions with the underlying mantle plume.

Analysis of the first 100 events reveals a concentration of low-magnitude earthquakes, with magnitudes between 0.2 and 2.7. Many clustered at depths of 1-2 km, indicative of brittle failure in the volcanic edifice as magma ascends. Notable peaks included events of magnitude 2.7 at 06:50 on 12 September and multiple magnitude 2.3-2.4 shocks later that day. The temporal distribution showed heightened activity during the initial 48 hours, tapering thereafter, a typical signature of swarm evolution in this setting.

Hawaii's geological history features episodic volcanic activity punctuated by seismic swarms. Since 2000, 109 such swarms have occurred in the area, with notable increases in frequency during 2020 (13 swarms) and 2023 (20 swarms). These events often precede or accompany eruptive phases at Kilauea, as documented in long-term monitoring by geophysical networks. The 2018 eruption, for instance, followed intense pre-eruptive seismicity, underscoring the value of swarm data for hazard assessment.

This swarm's parameters fit established models of Hawaiian volcanism, where fluid migration induces microfracturing. No surface deformation or eruptive activity was directly linked in available records, though continued monitoring remains essential given the region's high volcanic output.

References

• United States Geological Survey (USGS) Hawaiian Volcano Observatory reports on Kilauea seismicity.
• SeismoSight internal swarm classification data for S20240912.1.
• Geological Society of America publications on Hawaiian hotspot dynamics.