UPDATE: A seismologist has replied on my Twitter thread about this episode, and you can see her comments here. (As I mention in the episode, I had written to four different seismologists before speaking with Brent, asking for their take on what he has to say, but had not received a response from any of them.) I'm guessing there will be some back and forth here for a few days at least, and I'll post my thoughts after that has run its course.