Seismic Swarm VS20240416.1: Analysis Near Kilauea, Hawaii

Seismic swarm VS20240416.1 was recorded 9 km SSW of Volcano, Hawaii, on the Big Island. The sequence began at 23:22 on 15 April 2024 and concluded at 17:03 on 20 April 2024, spanning 113 hours and 41 minutes. A total of 130 earthquakes were detected during this period. The events occurred in a tectonically active zone associated with the Kilauea volcano system.

Analysis of the first 100 events reveals predominantly low-magnitude activity. Magnitudes ranged from 1.1 to 2.6, with the majority falling between 1.2 and 2.1. Depths were shallow, typically 0–5 km, though several events reached 10–13 km. Early activity on 15–16 April featured rapid successive quakes, including pairs at identical timestamps with magnitudes up to 2.6. Subsequent days showed continued clustering, with notable events on 17–19 April including a 2.6 magnitude quake at 1 km depth and deeper occurrences at 11–13 km. The pattern indicates episodic unrest rather than a single large rupture, consistent with fluid or magma migration processes.

The region lies within the Hawaiian volcanic chain, formed by a mantle hotspot beneath the Pacific plate. Kilauea, one of the world's most active volcanoes, features summit caldera and rift zones where magma movement frequently triggers earthquake swarms. The swarm location aligns with the volcano's southern flank, an area influenced by both volcanic and gravitational stresses. Historical monitoring by the U.S. Geological Survey Hawaiian Volcano Observatory documents persistent low-level seismicity here due to ongoing magma supply and flank motion.

Since 2000, 104 swarms have occurred in this locale. Annual counts show variability, with elevated activity in 2020 (13 swarms), 2023 (21 swarms), and 2018 (9 swarms). Earlier decades recorded fewer events, such as 3 in 2000 and 8 in 2003. This recent increase aligns with renewed eruptive phases at Kilauea, including the 2018 lower East Rift Zone eruption that reshaped local stress fields. Swarms often precede or accompany surface deformation and gas emissions, serving as indicators of magmatic recharge.

The VS20240416.1 sequence fits established patterns of Hawaiian seismicity, where shallow events dominate due to brittle failure in the volcanic edifice. Depths rarely exceed 15 km, reflecting the limited thickness of the lithosphere in this hotspot setting. No significant surface deformation or eruptive activity was linked to this particular swarm, underscoring that many swarms remain aseismic at the surface.

Ongoing monitoring remains essential given Kilauea's dynamic nature. Future swarms may provide further insights into magma pathways and flank stability.

References

USGS Hawaiian Volcano Observatory reports on Kilauea seismicity (2024 updates).
Global Volcanism Program, Smithsonian Institution: Kilauea volcano background.
Hawaii State Earthquake Data archives since 2000.