Seismic Swarm S20070617.1: Shallow Earthquake Activity Near Volcano, Hawaii

The seismic swarm designated S20070617.1 was recorded 9 km south-southeast of Volcano, Hawaii. Activity began at 12:16 on 17 June 2007 and concluded at 01:39 on 2 July 2007, spanning 349 hours and 22 minutes. During this interval, 411 earthquakes were registered, with the majority occurring at shallow depths consistent with volcanic-flank environments.

The first 100 events took place within roughly three hours of onset. Magnitudes ranged primarily between 1.5 and 3.0, peaking at 3.0 at 12:52:45. Depths clustered between 0 and 4 km, with isolated events reaching 6 km and 9 km. The sequence displayed a rapid initial rate that gradually declined, a pattern typical of short-term seismic swarms driven by fluid or magma movement.

The location lies on the southeastern flank of Kīlauea volcano within the Hawaiian hotspot chain. The islands formed through sustained mantle upwelling, producing basaltic shield volcanoes. Kīlauea’s south flank experiences frequent shallow seismicity linked to magma transport along rift zones and gravitational spreading of the edifice. Depths under 5 km commonly reflect brittle failure above active magmatic pathways.

Since 1 January 2000, twenty swarms have been documented in the region. Yearly totals include three in 2000, one in 2001, eight in 2003, four in 2004, one in 2005, two in 2006, and one in 2007. These recurrent episodes underscore the persistent volcanic-tectonic stress regime of the Kīlauea edifice.

Analysis of the initial events reveals predominantly low-magnitude, shallow quakes that align with historical patterns of unrest preceding or accompanying eruptive phases. The swarm’s duration and event count provide a useful benchmark for monitoring future episodes in this tectonically active setting.

References

USGS Hawaiian Volcano Observatory – Kīlauea geologic summaries
Hawaii State Earthquake Data Archives (2000–2007)
SeismoSight internal swarm classification records