Analysis of Earthquake Swarm VS20180307.1 Near Volcano, Hawaii

Earthquake swarm VS20180307.1 occurred 3 km west-southwest of Volcano, Hawaii, on the Big Island. The event sequence began at 16:56 on 6 March 2018 and concluded at 05:09 on 9 March 2018, spanning 60 hours and 12 minutes. During this period, 95 earthquakes were recorded.

The swarm exhibited predominantly low-magnitude events, with the largest reaching 2.6. Depths ranged from shallow levels near or above sea level to approximately 23 km, reflecting activity within the volcanic crust. Most events clustered between 5 km and 11 km depth, consistent with processes occurring in the upper volcanic system.

This swarm aligns with the geological setting of Kilauea volcano, where the Island of Hawaii experiences frequent seismic activity due to its position over the Hawaiian hotspot. Magma movement, pressure changes within the volcanic edifice, and associated faulting commonly trigger such sequences. The location places the swarm on the southwestern flank of Kilauea, an area known for both eruptive and intrusive volcanic processes.

Historical records indicate 42 swarms in the region since 1 January 2000. Annual distribution shows variability: three in 2000, one in 2001, eight in 2003, five in 2004, one in 2005, two in 2006, four in 2007, one in 2008, three in 2011, four in 2012, one in 2013, two in 2014, three in 2015, two in 2016, and two in 2017. These patterns underscore the recurrent nature of swarm activity linked to ongoing volcanic dynamics.

Insights from the timing and magnitude distribution of VS20180307.1 reveal an initial burst of activity on 6 March, followed by sustained seismicity through 7 and 8 March, tapering on 9 March. Shallow events dominated early phases, while slightly deeper occurrences appeared later, suggesting possible migration of stress or fluid movement within the subsurface.

Such swarms contribute to monitoring efforts around Kilauea, where seismic data help assess volcanic unrest. The 2018 timing coincides with a period of heightened activity preceding the major May 2018 eruption, illustrating how swarms can form part of broader volcanic cycles.

References
SeismoSight internal swarm classification data for VS20180307.1.
USGS Hawaiian Volcano Observatory geological summaries on Kilauea activity.
Hawaii Volcanoes National Park volcanic history documentation.