How Thick Is the Ground Beneath You? Lithosphere Thickness from Two Open Global Models

The lithosphere, the rigid outer shell of the Earth that makes up the tectonic plates, varies greatly in thickness, but most maps of it are published as images rather than numbers. I compare two openly licensed global models of the depth to the base of the lithosphere, LithoRef18 (Afonso et al. 2019) and WINTERC-G (Fullea et al. 2021), on a common 0.25 degree grid, and combine them with sea-floor ages, plate outlines, volcanoes and diamond mines. The two models give the same area-weighted global mean, 105 km, and correlate cell by cell at r = 0.74, with a median absolute difference of 19 km; they differ by more than 50 km over 8% of the surface, mostly beneath the East European Platform and Tibet. In the oceans, LithoRef18 thickens from a median of 42 km on sea floor younger than 2 million years to 118 km on sea floor older than 150 million years, tracking the square root of age (r = 0.88). On land the deepest roots lie under cratons. Of 1,828 volcanoes listed in Wikidata with a Global Volcanism Program number, 71% stand on lithosphere thinner than 100 km, while 87% of 63 diamond mines sit on lithosphere thicker than 150 km, with a median deeper than 92% of continental ground. The United Kingdom averages 115 km, close to the continental median. An interactive map accompanies the note. Both models are coarse and use thermal definitions of the boundary, so all values carry uncertainties of tens of kilometres. Interactive version: https://maps.tristanhotham.com/lithosphere-thickness/. Data and code: https://github.com/Tristan-Hotham/lithosphere-thickness. Blog post: https://blog.tristanhotham.com/2026/10/29/lithosphere-thickness/.