Seismic Swarm VS20000505.1: Analysis of Activity Near Volcano, Hawaii

A notable seismic swarm designated VS20000505.1 occurred southwest of Volcano, Hawaii, from 06:30 on 5 May 2000 to 10:50 on 12 May 2000. Over 172 hours and 20 minutes, the sequence produced 212 earthquakes. The events clustered 6 km southwest of the town of Volcano, a location situated on the flanks of Kīlauea volcano within the Hawaiʻi Volcanoes National Park region. Kīlauea forms part of the Hawaiian hotspot chain, where the Pacific plate moves over a mantle plume, sustaining one of Earth’s most active basaltic shield volcanoes. The southwest rift zone and adjacent areas frequently experience earthquake swarms driven by magma intrusion, dike propagation, and associated stress changes in the volcanic edifice. Depths in this swarm, predominantly between 5 km and 11 km, align with typical shallow crustal processes beneath Kīlauea’s southern flank. Examination of the first 100 recorded events reveals a compact temporal distribution beginning on 5 May. Magnitudes ranged from 1.1 to 2.5, with the majority falling between 1.6 and 2.2. Depths varied from surface levels to 13 km, though most clustered between 6 km and 10 km. Early activity on 5 May included events at 2.2, 2.4, and 2.0, followed by a steady sequence through 8 May featuring repeated magnitudes near 2.0. This pattern indicates sustained, low-energy brittle failure consistent with fluid migration rather than a single large tectonic rupture. Such swarms contribute to the broader seismic character of the Island of Hawaiʻi, where cumulative microseismicity helps delineate magma pathways and flank stability. Historical records maintained by SeismoSight note that only two swarms have been classified since 1 January 2000, with this event representing the first. Continued monitoring supports hazard assessment for nearby communities and infrastructure.

References

USGS Hawaiian Volcano Observatory – Kīlauea geologic summaries Hawaiʻi Volcanoes National Park – volcanic history resources