Correlation of the observed and synthetic magnetic anomaly profiles in the West Philippine Basin. The vertical-component anomalies are presented. (a) Synthetic magnetic anomaly profile assuming a half spreading rate of 1.8 cm/year, (b) observed anomaly profiles, (c) shaded topographic relief along 130° E from swath bathymetry data, and (d) synthetic profile assuming a half spreading rate of 4.4 cm/year. Skewness of 160°, magnetization intensity of 2.5 A/m, and magnetized layer top depth of 6 km and thickness of 1 km were assumed. The geomagnetic polarity timescale of Gradstein et al. (2004) is used. See Figure 2 for the locations of the magnetic profiles. Color scale of the shaded topographic relief is the same as Figure 2.