Fig. 5: Spatial configuration of historic earthquakes and BBP stations.

The epicentral location and focal mechanism are shown as a beachball for a Landers, b Hector Mine, c Northridge, d North Palm Springs, and e Whittier earthquakes. The BBP stations where the observations analyzed in this work were acquired are plotted in blue and separated into `inside' (stars) and `outside' (triangles) stations, referring to whether the stations are within or beyond the area covered by the synthetic training sites (magenta dots). This division stems from the generally poor extrapolation performance of ML models—we expect lower-quality predictions for stations that are far from the training locations. See the main text for a full definition of `inside' and `outside' locations.