Subduction without Subduction

Last week, we made a progress in analogue modelling of the so called ‘subduction zones’ without the process of subduction, just only via material cooling. The first ever experiment we performed was the one with Tonga/Lau Region.

We have learned a lot and based on the last experiment, we made a new experimental device and decided to run a new long-term project – SuZo-WiSu (Subduction Zones Without Subduction). The aim of the project is to create the subduction zones, as we observe them via P-wave seismic tomography, without the process of subduction. The aim is to study material cooling on the interfaces in deeper parts of materials via numerical and analogue modelling.

New Experimental Device

The experimental device is very simple. It consists of:

• heat source
• desk
• glassy ‘Section of Earth’
• continental oblique granitic block
• oceanic crust excavator
• paraffin wax (oceanic crust)

First, we put hard pieces of paraffin wax into the ‘Section of Earth’. Then, we light up the heat source and wait. We put the continental block inside the section and wait again. The process of material solidification is starting.

Now, it’s time to get the oceanic crust. We carefully raise the continental block and get the sample of the oceanic crust with our excavator.

The final results are here:

We see that we are able to create the so called presumed subduction zones also via cooling of a material. Without need for subduction. Here you can watch a video where I briefly explain the basic pillars of the new SuZo-WiSu project.

Problems

At the beginning of our experiments, we had a few problems. The biggest one was with isolation, as you can see here:

Every time you create a new device, you must test it and search for mistakes you made. We also had problems with the first desk. It almost exploded due to stress field that arised when lighting up the heat source. We decided to use a new desk that has really a shape of a desk, the last one was like ‘pool’ that we made out of 5 single glassy desks.