GD
Geodynamics

Rajani Shrestha

Rajani Shrestha is a graduate student in the Division of Geological and Planetary Sciences at Caltech. She is interested in both earthquake seismology and global seismology for earth structure and dynamics. She completed her MS from the University of Delaware where she investigated the deformational signals observed along the eastern North American margin using seismic anisotropy. You can reach Rajani via e-mail.

Dislocation Creep and the Development of Deformation Fabrics

Dislocation Creep and the Development of Deformation Fabrics

Assume you are under stress. What do you do? Take a walk in the park, order your favorite takeout, have a breakdown, or internally slip along preferred slip systems and develop a fabric? The response will mostly depend on what kind of material you are, how much stress you are under, and what environmental conditions you are subjected to. For instance, someone might listen to classical music after ...[Read More]

Don’t Stop Me Now: A Fracture Mechanics Perspective on Earthquake Nucleation

Schematic for a possible earthquake nucleation scenario. Inset figure adapted after Lebihain et al. (2021) and McLaskey (2019).

How do earthquakes start? Earthquakes occur when a block of rock rapidly slides past another along an interface or a discontinuity in the medium and release energy in the form of seismic waves. Turns out, the surface of the earth is riddled with a lot of these discontinuities, which we call “faults”. If we plot the locations of earthquakes on a world map (Figure 1a), we will see that they highligh ...[Read More]

Going Around Mars

Going Around Mars

One of our closest neighbors in the universe, the red planet, has long intrigued geoscientists. Mars has been the destination for multiple spacecraft missions. Two rovers, Curiosity and Perseverance, are still exploring the planet as of 2025. This week, let us go on a short tour around Mars and show a little love to this fascinating planet. We will start our tour by looking at the global topograph ...[Read More]

4th Cargèse School on Earthquakes: Nucleation, Triggering, Rupture, and Relationships to Aseismic Processes

Group photograph of the participants of the 4th edition of Cargèse school on earthquakes. Credit: Anthony Sladen.

How do earthquakes nucleate? How do they arrest? Can we predict or control them? How do fault zone structure and rheology influence rupture? What do earthquakes in the lab tell us? How does fluid injection modulate seismicity? The Institut des Etudes Scientifiques de Cargèse (IESC) premise in Corsica, France was abuzz with discussions about these and many other related questions this October. The ...[Read More]

Ambient seismic wavefield: how noise can be a signal

Ambient seismic wavefield: how noise can be a signal

Every now and then, the surface of our planet shakes violently during earthquakes like the recent magnitudes 7.8 and 7.5 Kahramanmaraş Earthquake Sequence in Türkiye. These vibrations are recorded by instruments called seismometers and are then processed and analyzed by seismologists to study the earthquake processes themselves as well as other deep Earth structures. Interestingly, seismometers al ...[Read More]

Magnets are cool, and….. so is the Earth!

Magnets are cool, and….. so is the Earth!

Magnets are cool, who does not like them? And the planet that we live in, the Earth, itself is a huge magnet. Not only does the Earth’s magnetic field protect us from harmful radiation from space, but it can also help us reveal some of the secrets of our planet. Local variations in the magnetic field can be used to probe the subsurface of the Earth from crustal to mantle depths. Although there is ...[Read More]

LLSVPs: Mysteries in the Deep Mantle

LLSVPs: Mysteries in the Deep Mantle

Did you know that there are big, blob-like anomalies in the deep mantle which are larger than a continent and rise up to hundreds of kilometers from the core-mantle boundary? Today’s post is all about those blobs and what we know and do not know about them. If you want to know more about why these blobs are so interesting to study, check out this other cool blog post by Jamie Ward. If you look at ...[Read More]

Into the anisotropic Earth

Into the anisotropic Earth

While we have sent several rovers to Mars, drilling down even just to the mantle of our own planet is a challenge that we are yet to overcome. How is it then that we know all these things about our planet’s interior? It turns out, we do not need to be inside the Earth to know what is happening there. Observations from geophysics and geochemistry can inform us about the processes and the properties ...[Read More]