Lake Unloading Drives Fault Slip and Rift Asymmetry in Southern Tibet

Abstract

The extent to which surface processes drive continental deformation remains a pivotal question in geodynamics. Here, we demonstrate that Late Quaternary lake-water unloading is a primary driver of fault slip and rift asymmetry in southern Tibet. Since the last interglacial (∼116 ka), significant water-level drops of large lakes have induced crustal rebound and Coulomb stress changes. At Nam Co Lake, a ∼130 m drop produced ∼0.1 MPa of stress change, preferentially reactivating the adjacent fault and contributing ∼15 m of vertical displacement ∼23% of the total near Damxung. Likewise, the southern lakes (Yamzho Yumco and Puma Yumco) caused ∼70 m of vertical displacement on the adjacent fault. We establish that climatically-controlled lake unloading can directly shape continental rifting by selectively enhancing fault slip on the lake-bounding side of the rift, thereby amplifying its structural asymmetry. This highlights a significant, quantifiable role of surface processes in actively shaping tectonic deformation.