Work

Teleseismic Radial Anisotropy Reveals a Sill‐Dominated Magma Reservoir Beneath the Valles Caldera, New Mexico

Year: 2026

Type: article

Abstract: The Valles Caldera (VC), one of the largest Quaternary silicic calderas in North America, formed by explosive rhyolitic eruptions. Seismic studies suggest a crustal magmatic reservoir beneath the caldera with low‐velocity anomalies, but resolving the detailed geometry of localized melt requires constraints from seismic anisotropy. To image P‐wave velocity and radial anisotropy using dense nodal array data, we develop a teleseismic tomography method that integrates an eikonal solver with the adjoint‐state approach. Our results reveal a pronounced low‐velocity anomaly (>20% reduction) extending laterally across the resurgent dome and down to 15–20 km depth, consistent with a crustal magma chamber. We also identify a colocated zone showing a previously unrecognized pattern of strong positive P‐wave radial anisotropy (up to 8%) where horizontally polarized P‐waves travel faster than vertically polarized ones. This anisotropy indicates a laterally extensive magmatic sill complex and provides new constraints on magma distribution and reservoir architecture beneath the VC.

Source: Geophysical Research Letters

DOI: 10.1029/2025gl120000

Authors: Gaoshan Guo, Haiqiang Lan, Tao Xu, Qinya Liu

Institutions: University of Toronto, Chinese Academy of Sciences, Institute of Geology and Geophysics

Language: English

Topic: Seismic Imaging and Inversion Techniques

Subfield: Geophysics

Field: Earth and Planetary Sciences

Domain: Physical Sciences

Open Access status: gold

Estimated APC paid: $3,190

Funders: Rice University, Chinese Academy of Sciences, Natural Sciences and Engineering Research Council of Canada