Seismic Swarm VS20230419.1: Analysis Near Volcano, Hawaii

The seismic swarm VS20230419.1 was recorded 5 km SSW of Volcano, Hawaii. It began at 00:33 on 19 April 2023 and concluded at 22:02 on 14 May 2023. Over 621 hours and 28 minutes, the swarm comprised 422 earthquakes. This event occurred within the tectonically active Hawaiian volcanic system, where swarms frequently reflect magma migration and crustal adjustments associated with shield volcano dynamics. Analysis of the first 100 events reveals predominantly low-magnitude activity. Recorded magnitudes ranged from 0.1 to 4.1, with the majority below 2.0. Depths were consistently shallow, concentrated between 0 and 4 km. Notable events included a magnitude 4.1 earthquake at 00:23 on 23 April 2023 at 1 km depth, alongside several magnitude 2.5–2.7 occurrences on 19–20 April. Timing showed clustering in the initial days, with events distributed across morning and evening hours, consistent with episodic stress release in volcanic settings. The Hawaiian Islands form above a mantle hotspot, driving persistent basaltic volcanism. The region near Volcano lies adjacent to Kīlauea, one of Earth’s most active volcanoes. Its south flank experiences frequent microseismicity due to gravitational spreading, dike intrusions, and hydrothermal processes. Depths under 5 km align with shallow crustal pathways where magma ascends or lateral intrusions occur. Since 1 January 2000, 81 swarms have been documented in the area. Annual counts include peaks of 12 swarms in 2020 and 9 in 2018, with lower activity in intervening years such as single swarms in 2001, 2005, and 2013. This pattern underscores recurring unrest tied to Kīlauea’s eruptive cycles and flank instability. References: USGS Hawaiian Volcano Observatory reports on Kīlauea seismicity. Hawaii Volcanoes National Park geological summaries.