Teleseismic tomography results

Figure 13.31: Ray density plots and horizontal slices through the Vs model at (a) 50 km depth, (b) 100 km depth and (c) 250 km depth. (d) shows vertical slice through the Vs model along the Newberry track with the ray density plot on the left, the map of cross-section in the middle, and the vertical slice on the right. The model grid spacing is 50 km in all three dimensions.
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This study uses a total of 53 broad-band seismic stations, 12 from OATS, and others from nearby permanent networks (BK, CC, US, UO, UW, PN, IU, TA, LI) and temporary deployments (XJ, YC, YS). In this preliminary study, we inspect events with magnitude 6.0 and above from July 19th, 2003 to Nov. 11th, 2004. For the S wave velocity model, a total of 95 events with useable S and SKS phases were recorded at 45 stations, and a total number of 2148 rays were used in the Vs inversioni. Our preliminary tomography results show large low velocity residuals all along the Newberry track to a depth $\sim $150 km and no further continuation to the deep mantle (Figure 13.31). This suggests there is no migrating melt body in the asthenosphere beneath the region, and supports the conclusion from our SKS splitting analysis that the Newberry track is more likely a result of lithospheric processes.

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