Fig. 2: Morphometry of the ISM coastal plain.

a Map of fitted plane to ridge crest points (topography data authors’ own). Note dip toward the northwest. Boxes indicate surveyed areas used for the composite topographic profile shown in (d). The inset shows a histogram of plane-fit residuals with a normal distribution curve. b Tilt during the 2010 earthquake and along the coastal plain. c Number of 2010-like tilt events required to achieve the plain tilt. Note the similarity with a number of beach ridges. d Composite topographic profile across the coastal plain indicating ridge numbers and width measurements (with 1 SD uncertainties).