2023 Kı̄lauea Horizontal-Component Signal/Noise Assessment of a Large Three-Component Nodal Array

Abstract

In spring 2023, 1,802 three-component seismic nodes were deployed over a 13 × 13 km area within and around Kı̄lauea Caldera, Hawai‘i. The continuous recordings include vibroseis signals from 396 source positions and more than 12,000 detected and located earthquakes. Three node types were installed across pāhoehoe and ‘a‘ā lava flows, volcanic tephra, and dense jungle. Because permits precluded burial, all nodes were surface-deployed and exposed to persistent trade winds. We use horizontal-to-vertical spectral ratios (H/V) to assess horizontal-component signal-to-noise ratio (S/N) as functions of frequency and wind speed, and to quantify how node geometry and deployment configuration affect wind sensitivity. Taller, narrower spike-mounted nodes are more susceptible to wind-induced rocking than shorter, wider nodes on leveling legs. Volcanic tremor produces strong horizontal noise at 1–5 Hz. Vibroseis sweeps were limited to frequencies >5 Hz, constraining weak S-wave detection to the same band, where wind-driven horizontal noise is often highest. We provide H/V estimates for all node data and for 12 United States Geological Survey (USGS) Hawaii Volcano Observatory (HVO) network stations. Based on H/V S/N estimates, we identify four station subsets: three suitable for earthquake and active-source S-wave detection and picking, and one of 1,099 stations suitable for lower-frequency (<1.2 Hz) interferometry.