Modelling the relative time-scales of the Rayleigh-Taylor Instability and delamination, using Underworld With Adam Beall, Cardiff University. Why model sub-continental gravitational instabilities? Within the plate tectonics framework, continents are generally considered to have a much lower density than the asthenosphere below and therefore avoid the kind of recycling that the oceanic crust and lithosphere undergoes.

Using physical units and how to appropriately scale a model is a top question users ask when beginning with Underworld. The equations Underworld solves are stated in a physically correct form, they remain valid as long as every material constant, geometry, time, etc., are expressed in the same system.  There is no explicit concept of units no scaling in Underworld, the choice is entirely left to the user.

In honour of Hans Mühlhaus' 70th birthday this month, here are some shear band simulations made with Underworld. We are investigating the role of dilatancy in the geometry of the shear bands for a box of material when a small trapdoor is opened. The extent to which large-scale deformation is needed to release material through the trapdoor depends on how much the material dilates when shear bands form.

Underworld2 is a python-friendly version of the Underworld geodynamics code which provides a programmable and flexible front end to all the functionality of the code running in a parallel HPC environment. This gives signficant advantages to the user, with access to the power of python libraries for setup of complex problems, analysis at runtime, problem steering, and coupling of multiple problems.

By the way, before you read this post, catch up with how we use docker by reading part 1 Docker allows us to distribute pre-built applications which are hosted in a virtual machine and are therefore platform independent.

While huge improvements in usability have been achieved in Underworld2, the installation process is still unfortunately as painful as ever. This difficulty is in large part due to Underworld's numerous dependencies, and also the multiple platforms we try to support. Compounding this, the legacy of a individual user's machine often conspires against success, rarely in obvious ways. Simply, compiling is not fun. Enter docker.

(aka the Underworld renovation project) Underworld is our parallel, particle-in-cell, finite element geodynamics code [1]. For the past year or so, the Underworld team has been working on a refurbished user interface. We've known for a long time that it needed to be done but we finally bit the bullet.

In a recent paper [1], we used Underworld models to examine subduction congestion associated with the ingestion of a continental ribbon. The SE Australian geological record turned out to be a wonderful place to study this process. Here is a short summary of the work for a relatively non-technical audience that we put together and some additional figures which I prepared.