Travel Time Delays Figure 8 Figure 8. The average teleseismic P-wave residuals across the array from earthquakes to the south east of the array. The average P-wave residuals from earthquakes to the northwest of the array. For each earthquake used in the time analysis, the average P and S wave residuals were removed to account for near source structure and origin time errors. The station residuals were then calculated from an average of the mean removed residuals.
Negative residuals indicate fast arrival times and positive slow.
The delays are slowest in the rift with comparable travel time delays to Plateau and Great Plains stations. The patterns from NW and SE earthquakes vary considerably indicating significant deep heterogeneity beneath the array. A particularly striking feature is the narrow zone of fast arrivals from earthquakes to the SE at stations 10-15. This indicates a rather strong, narrow fast structure exists on the east flank of the Rio Grande Rift. Further residuals will be measured and a tomographic inversion will be performed for both P and S waves in the near future.