A decade-long silent ground subsidence hazard culminating in a metropolitan disaster in Maceio, Brazil

Ground subsidence caused by natural or anthropogenic processes affects major urban areas worldwide. Sinkhole formation and infrastructure fractures have intensified in the federal capital of Maceio (Alagoas, Brazil) since early 2018, forcing authorities to relocate affected residents and place buildings under demolition. In this study, we present a 16-year history (2004-2020) of surface displacement, which shows precursory deformations in 2004-2005, reaching a maximum cumulative subsidence of approximately 200 cm near the Mundau Lagoon coast in November 2020. By integrating the displacement observations with numerical source modelling, we suggest that extensive subsidence can be primarily associated with the removal of localized, deep-seated material at the location and depth where salt is mined. We discuss the accelerating subsidence rates, influence of severe precipitation events on the aforementioned geological instability, and related hazards. This study suggests that feedback destabilization mechanisms may arise in evaporite systems due to anthropogenic activities, fostering enhanced and complex superficial ground deformation.

Automated summary

Ground subsidence, whether caused by natural or anthropogenic processes, is a global issue affecting major urban areas worldwide. The case study in Maceio, Brazil, highlights the accelerated sinking rates and the primary association of extensive subsidence with the removal of deep-seated material at the location and depth where salt is mined. This research suggests that destabilization mechanisms in evaporite systems due to human activities can lead to enhanced and complex ground deformation.