Figure 1
Stations used in this study to measure differential traveltimes between two stations as the function of frequency. Red and blue triangles indicate the broadband ocean bottom seismometers and island stations of the OJP array, respectively. The island stations operated by the Pacfic21 network are represented by blue triangles and the stations from IRIS data management center by yellow triangles. Red points indicate bounce points of the PP phase of which traveltime differences from the P phase are used for the inversion. Violet dotted line indicates the track of the Caroline hot spot41. Profiles of the cross sections in Fig. 2 are shown by red lines AB and CD with yellow dots at intervals of 5° from A and C, respectively. Pa Pacific plate, Au Australia plate, Ca Caroline plate, OJP Ontong Java Plateau, CH Chuuk, PN Ponape, KS Kosrae, NBT New Britain Trench, SCT San Cristobal Trench, and NFB North Fiji Basin. The Generic Mapping Tools (GMT) 5.4.553 was used to make this figure.
