Fig. 2
From: Seismological evidence for a localized mushy zone at the Earth’s inner core boundary
ICB study region and PKiKP–PcP differential travel time residuals. a Map view of the ICB study region (solid black box, with detailed results shown in Fig. 2b), along with seismic events (red stars, labeled by event ID listed in Supplementary Table 1) and stations (black triangles) used in the analyses. b Geographic distribution of PKiKP–PcP differential travel time residuals in the study region (corresponding to the solid black box in Fig. 2a), averaged over caps with a radius of 1° covering the PKiKP reflected points at the ICB (Supplementary Fig. 1 for a complete version). Cap-averaged residuals are plotted at the center of each cap and color-coded with each event, with positive and negative values denoted by circles and triangles respectively and the size of the symbol proportional to the absolute value of travel time residual. The ICB is grouped into regions according to their structural characteristics inferred based on seismic data, with black boxes (labeled as A: A1, A2, A3, and A4) indicating flat and sharp regions and blue box (labeled as B) a region with a laterally varying double-layered structure (mushy zone) across the ICB
