Three-dimensional velocity structure of the Kilauea caldera, Hawaii

High-resolution velocity models (0.5 km resolution) of the Kilauea caldera region are obtained by the tomographic inversion of both P- and S-wave arri val times. Data are from the permanent Hawaiian Volcano Observatory (HVO) s eismic network, a broadband seismic network, and a temporary array of stati ons centered on the southern boundary of the caldera. A low-velocity P-wave anomaly is imaged centered on the southeastern edge of the caldera, with a velocity contrast of about 10% and a volume of 27 km(3). The V-P/V-S model mimics the spatial extent of the P-wave anomaly, but is partitioned into t wo discrete anomalous volumes centered on the southern boundary of the cald era and on the upper east rift of the volcano. The corresponding Poisson's ratio in these zones is high (nu = 0.25-0.32) which is consistent with a de nsely-cracked, hot volume which may contain partial melt. The large-scale f eatures of the models are consistent with results obtained from an earlier, larger-scale (2 km resolution) tomographic image of Kilauea Volcano based on HVO network data.