Triangles are seismic stations of the Pacific Northwest Seismic Network used in our tomographic study.
Circles are earthquakes used in the inversion.
Open triangles are volcanoes. The model grid used for P-velocity inversions is shown by the light grid, with rows and column intervals labelled. Rows and columns shown as cross-sections in Figs. 6 and 7 are indicated by the bolder lines. These lines are indicated in the center of the cells, used for calculation of latitude and longitude for the cross-sections.