This dataset contains a three-dimensional seismic slowness model and MATLAB processing code derived from P-wave seismic data collected at Newberry Volcano in central Oregon. The associated study combines active-source first-arrival travel times with teleseismic P-wave delay times to jointly image upper-crustal velocity structure beneath the volcano (targeting the shallow crust to ~10 km depth). The included workflow uses a one-dimensional velocity model and a three-dimensional slowness model to compute a fractional velocity perturbation (dv/v) volume and to plot horizontal slices and vertical sections. The script reads the 1D model, interpolates it onto the depth grid of the 3D model, converts the 1D velocity profile to slowness, and then forms dv/v by comparing the 1D slowness volume to the 3D slowness model before plotting results. A python version of the workflow is also included, which was used to create the provided 3D model grid CSV files. These data have been used by and uploaded to the Geothermal Data Repository (GDR) as part of the DE-risking Exploration of geothermal Plays in magmatic ENvironments (DEEPEN) project. The data were originally produced through the 2008 Newberry Seismic Experiment, funded by a USGS Venture Capital grant and NSF grants (EAR-207670 and EAR-207671). Seismic data from the 2008 experiment and from earlier 1983 and 1984 USGS experiments are archived at the IRIS DMC. Please refer to the associated manuscript (linked below) for additional details on the original data collection and research acknowledgements.