Hunga‐Tonga Volcano Plumbing System Inferred From Virtual Seismometer Approach

Abstract We present a surface wave tomography application based on event‐pair interferometry to investigate local (∼100 km) mid‐ocean crustal structures, with a particular focus on imaging a potential crustal solidified intrusive complex in a region lacking seismic stations. We analyzed vertical‐component IRIS data (2010–2022) from over 180 M ≥ 4.5 earthquakes. Signal pre‐processing techniques, cross‐correlation, and then stacking, were employed to extract inter‐event empirical Green's functions (EGFs). Afterward, dispersion curves were manually derived for inter‐event distances exceeding three wavelengths, and tomographic inversion was performed to obtain isotropic and anisotropic group velocity models across periods of 1–12 s. Our results at shallow depths reveal well‐resolved low‐velocity anomalies, attributed to high porosity, low density, and the presence of unconsolidated to semi‐consolidated pelagic sedimentary deposits. In contrast, at greater depths, high‐velocity regions are interpreted as parts of the volcanic plumbing system inside the oceanic crust beneath seamount volcanoes in mid‐ocean settings, highlighting the effectiveness of the method despite the limitations imposed by widely spaced global physical stations. Additionally, observed anisotropy indicates deformation around Hunga Tonga‐Hunga Haʻapai (HTHH), with fast‐direction alignment reflecting magmatic intrusions and crustal fabric influences during crust formation. The V S models highlight structural variations and anisotropic features consistent with regional tectonics and magmatic processes.