Post‐Subduction Tectonics of Sabah, Northern Borneo, Inferred From Surface Wave Tomography

We use two-plane-wave tomography with a dense network of seismic stations across Sabah, northern Borneo, to image the shear wave velocity structure crust and upper mantle. Our model is used estimate crustal thickness depth lithosphere-asthenosphere boundary (LAB) beneath region. Calculated ranges between 25 55 km suggests extension in NW-SE direction, presumably due back-arc processes associated subduction Celebes Sea. β-factor be 1.3–2, well below initiation seafloor spreading. The LAB is, on average, at 100 km, which inconsistent models that ascribe Neogene uplift wholescale removal mantle lithosphere. Instead, region Plio-Pleistocene volcanism southeast, we 50–100 where lithosphere has thinned <50 supporting recent suggestions lower lithospheric through Rayleigh-Taylor instability.