How to generate deep earthquakes in the Hindu Kush? - A data driven modelling approach

Earthquake nests are defined as volumes of intense intermediate-depth seismicity which are isolated from any surrounding seismic activity. The high seismic activity within these earthquake nests occurs continuously and thus sets them apart from other seismic sequences such as earthquake swarms or aftershocks. Among the known earthquake nests, the Hindu Kush earthquake nest is the most active and has produced a large earthquake (MW ≥7) every 10-15 years. The intermediate-depth seismicity in this nest extends to a larger depth (up to 250 km) than in other earthquake nests and it is characterized by a bimodal distribution with an earthquake gap at approximately 150 km depth. Despite the depth of these earthquakes, they pose a significant seismic hazard. The continuous seismic activity is commonly related to subducting and detaching slabs.  
To understand the physical mechanisms and the tectonic environment of this intermediate-depth earthquake nest, we aim to conduct data-driven numerical simulations. These will determine the deformation state in the Hindu Kush and the controlling mechanisms of the detachment process. These data-driven models require two main ingredients: 1) a synopsis of existing data and 2) an understanding of the impact of model parameters (e.g. the rheology of crust, lithosphere and mantle). 
We used the open-source Julia package GeopyhscialModelGenerator.jl to create a synopsis of existing datasets of earthquake locations, seismic tomographies, Moho topographies and other datasets that will serve as the basis for the three-dimensional models.   
Based on this synopsis, we constructed 2D thermomechanical models incorporating a non-linear visco-elasto-plastic rheology to investigate the deformation state of a detaching slab and the underlying mechanisms controlling the detachment process. This analysis includes the effects of the subducted lower crust as well as the rheological properties of the eclogitized lower crust and the lithospheric mantle.
First results show that slab detachment depends on the viscosity ratio between the lower crust and lithosphere. Deeper initial depths of the lower crust, generate shorter detachment times. The detachment times increase linearly for shallower initial depths and the detachment time offset is smaller for increasing viscosity ratios. Increasing viscosity ratios create higher ratios of detachment depth to initial depth. The depth ratio offset is higher for larger viscosity ratios and shallower initial lower depths. The depth ratio varies by about 20% of the initial depth which is in the range of the Hindu Kush's earthquake nest.