Seismic Swarm VS20031206.1: Analysis of Activity near Kilauea Volcano, Hawaii

Seismic swarm VS20031206.1 occurred 5 km southwest of Volcano, Hawaii, on the Big Island. The sequence began at 03:09 on 5 December 2003 and concluded at 00:33 on 9 December 2003, spanning 93 hours and 24 minutes. During this interval, 63 earthquakes were recorded, with magnitudes ranging from 1.2 to 2.2 and focal depths between 1 km and 12 km.

The Hawaiian Islands formed through hotspot volcanism, where the Pacific Plate moves over a mantle plume. Kilauea, one of the world's most active volcanoes, lies within Hawaii Volcanoes National Park and has exhibited persistent eruptive behavior for centuries. Its summit caldera and rift zones are sites of frequent magma intrusion and associated seismicity. Earthquakes in this region commonly result from stress changes induced by magma movement, dike propagation, and volcanic inflation or deflation.

The December 2003 swarm displayed typical characteristics of volcanic seismicity, with events clustered in time and space. Initial activity on 5 December included multiple events exceeding magnitude 1.5, peaking with a magnitude 2.2 quake at 14:20. Activity continued through 6 and 7 December at a steady rate before tapering on 8 and 9 December. Depths remained predominantly shallow to intermediate, consistent with processes occurring within the volcanic edifice and upper crust.

Historical records indicate that seismic swarms have been recurrent in the area. Since 1 January 2000, ten such swarms have been documented, distributed as follows: three in 2000, one in 2001, and six in 2003. These episodes reflect ongoing adjustments within Kilauea's magmatic system and underscore the dynamic nature of the volcano.

This swarm provides insight into short-term seismic patterns that may accompany volcanic unrest. Low-magnitude events distributed across a narrow depth range suggest localized stress release rather than large-scale tectonic faulting. Continued monitoring by the Hawaiian Volcano Observatory supports assessment of potential links to eruptive cycles.

References

USGS Hawaiian Volcano Observatory. Kilauea Volcano Summary.
USGS Earthquake Catalog. Hawaii region events 2000–2003.
Tilling, R.I., et al. (2010). Eruptions of Hawaiian Volcanoes. USGS Professional Paper.