The moment for nuclear power to save us was twenty years ago – and it didn’t happen

Via Dr. Jonathan Foley on Twitter, a recent opinion piece in the NYT argues that despite it remaining popular amongst some advocates, “Nuclear power still doesn’t make much sense”.

The problem with nuclear is that we’ve been having the same conversation for 20 years or more. In the absence of heavy government subsidy, no one has built much. And we seem no closer to working out how to build nuclear plants more quickly and cheaply.

Is an alternative reality where massive oil & gas subsidies were shifted to nuclear in the 1990s and 2000s one where we’d be in a better climate & emissions situation? Maybe. However, the need in that parallel universe to overcome strong environmental & petrobusiness headwinds seem to make it a rather unlikely counterfactual.

In our actual reality, as the NYT piece argues, other solutions have now emerged with compelling speed and cost advantages, and less environmental baggage – however unfair you think the latter is. And because we’ve left our response so late, speed matters most of all.

[collated from this Twitter thread]

Categories: environment, society

A deep origin for the Tohoku earthquake?

So if I’m reading this summary in Eos right, there is a new study suggesting that there was significant deformation of the subducted plate in the lead up to the M9 2011 Tohoku earthquake occurred – enough mass was redistributed to measurably change the local gravity field.

There is a mechanical connection between the sinking/subducting plate and the surface – that’s what generates the ‘slab pull’ force that is one of the main drivers of plate tectonics. So a connection – whereby deformation deeper beneath Japan influenced the behavior of the the megathrust near the trench – is not implausible.

Cross-section through subduction zone at Japan Trench, illustrating the proposed sequence of events suggested by gravity data ahead of the 2010 Tohoku earthquake, where deformation in the deep slab preceded the shallow rupture at the trench.

However, the normal caveats about stuff like this apply:

  • finding a signal after the fact for one earthquake does not mean that we can reliably detect such signals before other earthquakes.
  • finding a potential signal does not mean we can predictably understand what it means.

In other words, we still can’t predict earthquakes.

[post collated from this Twitter thread]

Categories: earthquakes, geohazards, geophysics, tectonics

Just published: can sandbox models be educational and fun?

Just out: a paper by me and education expert Bridget Mulvey grapples with the question: analogue sandbox models are cool, but are they effective teaching tools?

Analogue sandbox models are a way of demonstrating tectonic deformation processes in the classroom: the weirdness of physical scaling laws means that slowly squeezing and stretching a tub of sand produces faults and folds like those produced in the crust over geological timescales.

Example of a sandbox model experiment where layers of colored sand have been deformed by horizontal compression. Photo by Chris Rowan.
Another compressional experiment, but this time with a layer of icing sugar (confectioner’s sugar), which is more cohesive and therefore stronger, beneath the layers of sand, and a layer of glass microbeads, which are weaker, within them. Photo by Chris Rowan.

After building a sandbox model for some research, I wanted to use it in my classes, but the results of the first attempts were… disappointing. The students enjoyed running the experiments, but it didn’t seem to help them understand any better what structures you get in response to different strains, and the effect of weaker or stronger layers.

So, inspired by this article in Eos on cycle-based learning, I developed an activity where we did multiple runs of experiments, with students sketching predictions of what would happen beforehand, assessing those predictions afterwards and also reassessing predictions for experiments that have yet to be run. We kept track of how students’ understanding developed during the multiple cycles by scoring their predictive sketches for how realistic they were. We also tested their general spatial skills with a test before and after the activity.

And we did see improvements! Especially in students who had low scores in the spatial skills test taken before the activity, who did much, much better in the post-test. And importantly, students still seemed to enjoy this more structured activity.

So yes: analog sandbox models are cool, and can be effective teaching tools – if you design an activity that helps students focus on the things you want them to learn.

This post was collated from this Twitter thread.

Categories: geology, publication, science education, structures, tectonics

The long-term seismic impact of mega thrust earthquakes

Here’s a very interesting analysis of aftershock patterns in the wake of M9+ megathrust events: the aftershocks in a ‘core’ region closest to the rupture shut off within a few years of the main shock, after which seismicity might remain very low for centuries. However, within a larger ‘corona’ of stressed rocks around this core region, seismicity is boosted for decades.

Graph of aftershock rate against time relative to background levels for 300 years after a large megathrust earthquake. Schematic in top right shows relative distribution of core (blue) and corona (red) zones, which are plotted separately. In the core, the blue line shows a period of activity below background starting within a few years and persisting for several centuries; in the corona the red line shows a decline to background within a few decades.
Model of aftershock rate against time relative to background levels for 300 years after a large megathrust earthquake. Schematic in top right shows relative distribution of core (blue) and corona (red) zones, which are plotted separately. From Stein & Toda (2022).

One think I like about this model is how it reconciles the known history of large earthquakes on the Cascadia megathrust with its historical lack of much seismicity at all, which for some time led us to dangerously underestimate the risk it posed to the Pacific Northwest. It’s still recovering from the last rupture in 1700. Furthermore, perhaps as it starts to evolve towards rupturing again in the future, we might expect to see a bit more low-level seismicity in the ‘core’ region.

[collated from this Twitter thread]

Categories: earthquakes, geohazards, geology

Not enough people get taught Earth Science, and that’s a problem for all of us

This article articulates an increasingly concerning question: in a world where increased exposure to natural hazards, resource scarcity and the consequences of climate change are amongst the most critical issues facing our society, why does Earth Science get no love in our education system?

I spend a lot of time teaching non-science majors basic Earth Science, and it does sting a little when students say they took your class because they thought it would be easy, not because it’s interesting or important. Sometimes, I manage to change their minds, which is quite nice. And my job!

But I can’t help but worry about the many, many people who I don’t even get the chance to convince. Should people having the information they need to make well-informed decisions about the defining issues of this century be dependent on them going to college and taking a non-compulsory course to meet their general education requirements? I’d argue not.

Furthermore, we can’t ignore the potential impact this has on the lack of diversity in Earth Science: how many fantastic people who could have contributed to our understanding of the planet, and how to sustainably live on it, have passed Earth Science by, not even realising it was there?

Categories: geology, science education