Seismic Swarm VS20230607.2 Near Volcano, Hawaii

A seismic swarm designated VS20230607.2 was recorded 6 km west-southwest of Volcano, Hawaii. The sequence began at 20:48 on 6 June 2023 and concluded at 06:30 on 8 June 2023, spanning 33 hours and 42 minutes. During this interval, 84 earthquakes were detected, with magnitudes ranging from 0.1 to 3.4 and focal depths predominantly between 0 and 5 km.

The swarm exhibited a typical pattern of clustered, low-to-moderate magnitude events concentrated in the shallow crust. Notable activity included a magnitude 3.4 earthquake at 12:35 on 7 June, followed by several events above magnitude 2.0 throughout the afternoon. The highest concentration occurred between 11:00 and 15:00 on 7 June, when more than 30 events were registered within a few hours. Depths remained consistently shallow, consistent with volcanic or hydrothermal processes in the region.

The location lies within the tectonically active zone associated with Kilauea volcano on the Island of Hawaii. Kilauea is a shield volcano characterized by frequent magma intrusions, flank movement along the south flank, and persistent seismic activity driven by volcanic and gravitational forces. The area experiences regular earthquake swarms linked to magma migration, pressure changes in the summit reservoir, and adjustments along rift zones. These events are monitored continuously by the U.S. Geological Survey Hawaiian Volcano Observatory.

Historical records indicate that seismic swarms are a recurring feature of the region. Since 1 January 2000, 88 swarms have been documented near Volcano. Annual counts show variability, with notable increases in 2018 (10 swarms), 2020 (13 swarms), and sustained activity through 2021–2023. This pattern reflects ongoing volcanic dynamics at Kilauea, including multiple eruptive episodes and intrusive events during the past two decades.

Analysis of swarm VS20230607.2 reveals characteristics common to volcanic swarms in Hawaii: rapid onset, high event rates over short periods, and shallow hypocenters. The absence of a single dominant mainshock and the tight spatial clustering align with fluid-driven or magma-related triggering mechanisms. Such swarms often precede or accompany changes in volcanic unrest, though this particular sequence did not culminate in surface eruption.

Continued monitoring remains essential given the high baseline seismicity of the Kilauea system. Future swarms will be evaluated against this established historical context to assess potential escalation.

References:
U.S. Geological Survey Hawaiian Volcano Observatory seismic catalogs
Hawaii Volcanoes National Park geological summaries
Internal SeismoSight swarm classification database