LC: So the “big questions” in biology are like where did life come from, what causes disease, how can we fight disease, how does the brain work, etc… What are your geology questions, what are the Nobel prize targets?
ML: I’ll reel off a few, and first I’ll build on what I said about subduction zones. Subduction zones are the fundamental plate tectonics setting that drives how the earth evolves, and we don’t know how they start and there’s a lot we don’t know about how they behave.
In thinking about the deep earth, there’s a lot. We have a pretty amazing ability to make images of the deep earth. You might think that you go deep into the mantle and it’s a bunch of mantle rocks, how exciting can it possibly be? But, it turns out that when you make a map or an image of the Earth’s interior, there are these two enormous, giant blobs of rock through which seismic waves are slower, maybe they’re hotter or maybe they have different chemical composition, sitting around. One is right beneath Africa and one is beneath the Pacific Ocean, both near Earth’s equator. We have known about these things for a while, at least a couple decades, and with time we get better and better images of them but we don’t know what they are, how they got made, what maintains them, what role they play in helping to set the pattern of mantle convection. We kind of have no idea. So that’s another one.
I don’t work on earthquakes myself–that’s a funny thing for a seismologist to say. I mostly use earthquake waves to image the deep earth, but it’s a question that people have been asking for a very long time: I don’t want to use the P word Predict, because I don’t think the way earthquake prediction the way the public would understand it is actually doable, but how do we make sense of earthquake hazards and mitigate damage. I don’t know how many tens of millions of people, just how much human life and infrastructure is vulnerable to earthquakes. How we wrap our heads around that and prepare for it is a major question.
I’m also curious, mostly out of sheer ignorance, what you think Earth Science and Geology’s greatest accomplishments have been.
Okay, so I’m going to come at this from my own perspective as a seismologist who mostly works on solid earth problems. Both of my answers are going to tie closely to what I see as the unsolved problems because they’re not unrelated.
The theory of plate tectonics is an amazing tour de force accomplishment on par with like Darwin articulating the theory of evolution. Of course there’s still much we don’t understand and a lot of questions that have come out of the formulation of the theory, but that is just a major intellectual accomplishment in the history of humans. No one has asked me, but I think there should’ve been a Nobel Prize for plate tectonics. I think it’s that big of a deal. That is certainly one.
I’ll also say, for all that we don’t know still about earthquake hazards and how to mitigate damage from earthquakes, we have learned so much over the last thirty years about where earthquakes happen, why different types of earthquakes happen in different places. In areas where we have good instrumentation and good data, it’s not very many regions, but in those places our knowledge of what the likely earthquake scenarios are and how likely they are is actually pretty advanced. That, I would say, is a major accomplishment.