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The deforming Nazca slab in the mantle transition zone and lower
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mantle: Constraints from teleseismic tomography on the deeply
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subducted slab between 6° and 32°S
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Alissa Scire1*, George Zandt1, Susan Beck1, Maureen Long2, and Lara Wagner3
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USA
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Connecticut 06511, USA
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Department of Geosciences, University of Arizona, 1040 E. 4th Street, Tucson, Arizona 85721,
Department of Geology & Geophysics, Yale University, 210 Whitney Ave, New Haven,
Department of Terrestrial Magnetism, Carnegie Institution of Washington, 5241 Broad Branch
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Road, NW, Washington, DC 20015, USA
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*
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Technology, 801 Leroy Place, Socorro, New Mexico 87801, USA
Current address: IRIS PASSCAL Instrument Center, New Mexico Institute of Mining and
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SUPPLEMENTAL MATERIAL
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Figure S1. Plot of tradeoff analysis for the P-wave inversion between the variance reduction and
the Euclidean model norm (L2) performed to choose preferred overall damping (D1-D10) and
smoothing (S1 –S10) weights. The black star shows the damping (D5) and smoothing (S4)
parameters used in this study.
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Figure S2. Normalized hit quality plots for P-wave tomography model. Hit quality for a node is
based on the number and azimuthal distribution of rays that sample that node. Good hit quality is
indicated by red shading while poor hit quality is indicated by blue shading.
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Figure S3. Horizontal depth slices for the checkerboard tests for a selection of model layers.
Input for neutral layers (0% velocity deviation) is not shown. Output for neutral layers (455 and
715 km depth) is shown in the left column. Resolution of velocity anomalies in neutral layers
shown here indicates that some vertical smearing is occurring. On the right is the input and
output for the layers with the checkerboard anomalies. The checkerboard tests show that while
amplitude recovery remains good in the center of the model space, lateral smearing increases
towards the edge of the model, particularly in the lower mantle.
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Figure S4. Trench perpendicular cross sections through checkerboard tests. Cross section
locations are as shown in Figure 1. Irregular distribution of anomalies with depth in synthetic
input (left) is due to the dilation of the node spacing with depth.
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Figure S5. Horizontal depth slices for the upper mantle (95 to 365 km depth) from the
tomography model. Dashed lines are the same as in Fig. 5. Stars mark locations of seismic
stations used in the study. Red triangles mark location of Holocene volcanoes (Global Volcanism
Program, 2013). Solid black lines are slab contours from Slab1.0 model (Hayes et al., 2012).
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