Thermo-Geodynamic Urban Destabilization: A Coupled Hydro-Thermal-Mechanical Framework Linking Urban Heat Islands and Land Subsidence

Abstract

Rapid urbanization alters land-surface properties, hydrological regimes, and subsurface stress states. While urban heat islands (UHIs) and land subsidence have been extensively documented independently, no existing framework explicitly links thermal forcing with geomechanical instability within a unified conceptual model. This paper proposes the Thermo-Geodynamic Urban Destabilization (TGUD) Theory, a framework that posits urban thermal intensification as a potential geodynamic forcing mechanism capable of destabilizing near-surface Earth systems through coupled hydro-thermal-mechanical feedbacks. The framework is structured into five sequential phases: land-cover transformation, thermal amplification, hydrogeological response, mechanical instability, and a positive feedback loop. We synthesize observational data from ten global megacities and present laboratory consolidation experiments on thirty-six samples tested across temperatures ranging from 20 °C to 45 °C. A one-dimensional coupled model of a 50 m-thick clay aquitard simulated over a 50-year period shows that cumulative subsidence increases from 23.7 mm under a no-UHI scenario to 57.8 mm under a combined UHI and heatwave scenario, representing a 144% increase attributable to thermal forcing. Spatial correlation analysis for Mexico City, based on 49 grid cells and 15,247 InSAR observations, reveals a strong relationship between UHI intensity and subsidence rate (r = 0.94, p < 0.001), even after controlling for groundwater drawdown. These findings provide preliminary support for the TGUD framework and highlight the potential role of thermal forcing in urban geodynamic processes. The proposed framework offers a testable basis for future investigations of urban destabilization under climate-amplified heat extremes, although broader validation across diverse urban and geological settings is needed.