Seismic Swarm VS20180417.1: Analysis of Activity Near Volcano, Hawaii

Seismic swarm VS20180417.1 occurred 4 km southwest of Volcano, Hawaii, on the Big Island. The sequence began at 11:16 on 16 April 2018 and concluded at 10:36 on 18 April 2018, encompassing 40 earthquakes over 47 hours and 19 minutes. Magnitudes ranged from 0.4 to 2.8, with focal depths predominantly between 0 and 10 km and occasional events reaching 18–26 km. The largest event measured magnitude 2.8 at 8 km depth on 17 April.

This swarm reflects typical seismicity associated with Kilauea volcano, one of Earth’s most active shield volcanoes. Kilauea forms part of the Hawaiian hotspot chain, where magma ascent through the Pacific plate produces frequent shallow earthquakes and occasional deeper events linked to magma movement or fault slip. Depths recorded in the swarm align with known patterns of brittle failure in the volcanic edifice and surrounding crust.

The region has experienced recurrent seismic swarms since at least 2000, with a total of 45 documented swarms through 2018. Annual counts include three in 2000, one in 2001, eight in 2003, five in 2004, one each in 2005 and 2008, four in 2007, three in 2011, four in 2012, one in 2013, two in 2014, four in 2015, two each in 2016 and 2017, and two in 2018. These episodes commonly occur in clusters along the volcano’s rift zones and summit area, driven by magma intrusion or pressure changes within the plumbing system.

Geologically, the Big Island comprises five coalesced shield volcanoes built over millions of years. Kilauea’s surface is dominated by basaltic lava flows, pit craters, and caldera structures. Seismic swarms often precede or accompany eruptive phases, as stress changes propagate through the crust. Depths under 10 km in the present swarm are consistent with shallow reservoir dynamics beneath the southwest flank of the volcano.

The 2018 swarm contributed to the broader seismic record leading into heightened volcanic unrest later that year. Monitoring by the Hawaiian Volcano Observatory continues to track such sequences to refine eruption forecasts. Data from the swarm illustrate the characteristic low-to-moderate magnitude, shallow focus, and short duration typical of Hawaiian volcanic seismicity.

References

USGS Hawaiian Volcano Observatory reports on Kilauea seismicity (2018 updates)
Hawaii Volcanoes National Park geological summaries
Smithsonian Global Volcanism Program database entries for Kilauea