Prof. Hemin Koyi

Biography

Professor Hemin Koyi earned a PhD in Tectonics and Geodynamics from Uppsala University. He was a Research Fellow at the Bureau of Economic Geology at the University of Texas at Austin. Since 2007, he has been leading the renowned Hans Ramberg Tectonic Laboratory at Uppsala University. Hemin Koyi has served as a chair and panel member on both national and international research council committees.

Hemin Koyi’s research interests focus on rock deformation in the crust and upper mantle, covering the fields of Structural Geology, Tectonics, and Geodynamics. In his work, he combines geological and geophysical data with geomechanical modeling to study the 4-D evolution of geological structures in both brittle and ductile tectonic settings. Beyond their fundamental importance, Hemin Koyi’s research applies to various fields: energy and mineral resources; waste disposal sites (Environment); seismic activity, landslides, and slope stability (Natural hazards); and groundwater flow and aquifer deformation. These studies have led to over 180 peer-reviewed articles in international journals.

Introduction of the Lecture

How safe is the “safe”? Salt diapirs as repositories for radioactive waste and storage sites

Thick evaporite layers in different sedimentary basins have formed salt structures of varying sizes. Besides serving as seals for hydrocarbons, salt structures are targeted worldwide as geological storage sites and long-term repositories for hazardous waste disposal. Some salt successions include interbedded denser lithologies. The long-term stability of salt structures depends on numerous factors, including the dynamic interaction between denser layers and evaporite layers. During the formation and rise of salt structures, the interbedded denser lithologies break into slabs, sometimes up to kilometres long, and are carried by the rising diapir. Understanding the deformation caused by such entrained inclusions within a diapir used for storage is crucial. We examine the Gorleben salt diapir in Germany, which has been considered for high-level radioactive waste disposal, to assess risks posed by entrained blocks. This extensively studied salt diapir contains large blocks of denser Anhydrite, up to 1 km long, transported upward by the rising diapir. The blocks are detached segments of layers that were initially part of the interbedded lithologies within the salt. However, such dense blocks are unstable within an inactive diapir and could sink over time. Field examples, along with results from analogue and numerical models, suggest that these sinking denser blocks could significantly impact the stability of any repository established within such salt diapirs.