Knowing exactly where faults are located is important both for scientific reasons and for assessing how much damage a fault could inflict if it ruptured and caused an earthquake. In the podcast, Rufus Catchings describes how we can use natural and artificial sources of seismic waves to create high-resolution images of fault profiles. He also explains how faults can act as seismic waveguides, an effect that enables us to determine whether faults are connected to each other. In Napa, a famous wine-growing area near San Francisco, he used guided waves to determine that an active fault is actually ten times longer than previously thought. Rufus Catchings is a Research Geophysicist at the US Geological Survey (USGS). Over the past 40 years, he has studied many dozens of faults in California and elsewhere to pin down their precise locations and help assess the risks they pose.

During the past couple of decades, we have discovered that stars with planetary systems are not rare, exceptional cases, as we once assumed, but actually quite commonplace. However, because exoplanets are like fireflies next to blinding searchlights, they are incredibly difficult to study. Yet, as Sara Seager explains, we are making astonishing progress. Various ingenious methods and the use of powerful space telescopes enable us to learn about exoplanet atmospheres and even, in some cases, what their surfaces consist of.

Sara Seager’s research concentrates on the detection and analysis of exoplanet atmospheres, and she has just won the prestigious Kavli Prize for this work. She has had leadership roles in space missions designed to discover new exoplanets and find Earth analogs orbiting a sun-like star. She is a Professor of Aeronautics and Astronautics, Professor of Planetary Science, and Professor of Physics at the Massachusetts Institute of Technology.

We have only a tantalizingly small number of sources of information about the Earth’s deep mantle. One of these comes from the rare diamonds that form at depths of about 650 km and make their way up to the base of the lithosphere, and then later to the surface via rare volcanic eruptions of kimberlite magma. In the podcast, Evan Smith talks about a new class of large gem-quality deep-mantle diamonds that he and his coworkers discovered in 2016. Inclusions within these diamonds serve as messenger capsules from the deep mantle. They show an unmistakable genetic link to subducted oceanic slabs, and thus give us clues as to what happens to subducted slabs as the pass through the lower mantle transition zone.

Evan Smith is a Senior Research Scientist at the Gemological Institute of America, New York.