Seismic Swarm S20231018.1 Near Volcano, Hawaii

A seismic swarm designated S20231018.1 was recorded 15 km south-southwest of Volcano, Hawaii, on the Big Island. The sequence began at 04:57 on 17 October 2023 and concluded at 15:36 on 19 October 2023, spanning 58 hours and 38 minutes. During this period, 35 earthquakes were detected, with magnitudes between 0.6 and 2.6 and focal depths predominantly between 0 and 3 km. The events clustered tightly in time, with the majority occurring on 17 October. Early activity included multiple events of magnitude 1.7 at depths of 0–1 km, followed by slightly larger shocks reaching 2.6. Activity continued through the night and into 18 October, featuring isolated events up to magnitude 2.5. The final recorded earthquake, magnitude 1.6 at 1 km depth, marked the swarm’s end on 19 October. Such swarms are characteristic of the Kilauea volcanic system, where shallow magma movement and associated stress changes produce frequent earthquake clusters. Depths recorded in this swarm align with typical brittle failure zones above the shallow magma reservoir beneath the East Rift Zone and summit area. Historical patterns confirm the region’s high seismicity; since 2000, 94 swarms have been documented, with notable increases in 2018 (9 swarms), 2020 (13 swarms), and 2023 (11 swarms). Kilauea remains one of the world’s most active volcanoes. Its ongoing eruptive history, driven by hotspot volcanism, produces persistent low-level seismicity punctuated by swarms linked to dike intrusions and rift-zone inflation. Depths under 6 km are consistent with the volcano’s shallow plumbing system, where magma pressures frequently exceed the strength of surrounding rock. This swarm’s modest magnitudes and shallow depths indicate no immediate threat of larger tectonic release or significant surface deformation beyond routine volcanic processes. Continued monitoring by the Hawaiian Volcano Observatory supports timely assessment of any escalation.

References

SeismoSight internal swarm catalog S20231018.1 USGS Hawaiian Volcano Observatory earthquake archive (2000–2023)