Current projects:

  • Measuring mantle attenuation in Cascadia I'm working to understand surprisingly high attenuation beneath the Juan de Fuca and Gorda ridge axes. We have the most comprehensive body wave measurements of mid-ocean ridge attenuation to date, and the high attenuation (Q<30 down to >100 km) implicates a strong signal from melt beneath the ridge axes. 

  • Geodynamical models of mantle convection with dynamically evolving grain size  We harness experimentally derived scaling relationships to turn the output of our collaborators' fantastic dynamical models (giving temperature, pressure, and grain size that evolves with stress) into predictions for the things we'd seismically observe (wave speed, attenuation). This gives us a tool to quantitatively compare the model outputs to each other and to the real Earth. We find that we can constrain some of the important parameters in the lower mantle. We also learn that tradeoffs between grain size and temperature mean that standard interpretations of tomographic models might be significantly under-estimating temperature variations in the mantle.

  • Imaging cratonic structure in the Northern Central US  Working with Karen Fischer, I'm developing a joint inversion of S-p and P-s receiver functions and surface wave phase velocities to pin down the 3-D velocity structure of the Wyoming Craton. We're particularly interested in constraining the character of the (seismic) lithosphere-asthenosphere boundary, and its implication for the long-term evolution and stability of continental interiors. 

Research areas:

Structural seismology

 

I use seismology as a tool to study the Earth's interior. I seek to understand regional and global tectonics, asking questions such as: What is the deep structure of continental rifts? How cold are subduction zones? What limits the depth and distribution of earthquakes? How much (if any) melt is there beneath the plates?

Selected papers:
Eilon et al. (2015) Imaging continental breakup using teleseismic body waves: The Woodlark Rift, Papua New Guinea
Eilon et al. (2016) A Joint Inversion for Shear Velocity and Anisotropy: The Woodlark Rift, Papua New Guinea

Vertical slice through tomography model from Eilon et al. [2015] showing slow (red) rift axis, and local seismicity.


Inverse theory

 

Most geophysical research rests either implicitly or explicitly on ideas from inverse theory - the mathematical framework for relating what we can observe to what we want to know.   I employ seismic tomographic techniques to make detailed models of the Earth's interior, relating sparse data at the surface to complicated 3-D structure at depth.  I am interested in: How well do observations constrain models? What lies hidden beyond the resolution of our data? What are the relative strengths and implications of different inverse theoretical methods (e.g. Bayesian, least squares, Newton's method)?

Selected papers:
Menke & Eilon (2015) Relationship Between Data Smoothing and the Regularization of Inverse Problems
Eilon et al. (2016) A Joint Inversion for Shear Velocity and Anisotropy: The Woodlark Rift, Papua New Guinea
Eilon & Fischer (in prep.) Constraints on mid-lithospheric cratonic structure from a Bayesian inversion of multiple seismic datatypes.

By stacking error surfaces from individual shear wave splitting measurements we can tightly constrain average splitting for a station. From Eilon et al.. [2014].

Result of a joint body-surface wave inversion within the Wyoming Craton, showing Vs profile and histograms of posterior model parameters


Anisotropy

 

Anisotropy (directional dependence of some physical property, often wave speed) offers a fascinating insight into fabric or structures within the Earth. In turn, this can tell us about flow of rocks over time, the mineralogy at depth, and/or the presence of organised melt. 

Selected papers:
Eilon et al. (2014) Anisotropy beneath a highly extended continental rift
Eilon et al. (2016) A Joint Inversion for Shear Velocity and Anisotropy: The Woodlark Rift, Papua New Guinea

Figure from Eilon et al. [2016] showing shear wave splitting through a hexagonally symmetric anisotropic fabric.


Attenuation and anelasticity

 

Attenuation, or loss of seismic energy due to frictional processes as waves propagate, offers a powerful complement to seismic velocity for discriminating the physical state of the Earth's interior. I am interested in making observations of seismic attenuation and harnessing laboratory-derived anelastic scaling relationships to translate those observations into estimates of temperature, composition, melt content, water content, etc. at depth. It's an exciting time to work on this: the experimental rock mechanics community and seismological communities are converging steadily on robust links between what we see in the Earth and what we know from the lab. This collaboration holds real promise for allowing us to not just image, but understand, the Earth beneath our feet. 

Selected papers:
Eilon & Abers (2017) High seismic attenuation at a mid-ocean ridge reveals the distribution of deep melt
Dannberg et al. (2015) Grain size evolution in the mantle and its effect on geodynamics, seismic velocities, and attenuation

Attenuated waveforms recorded across the Juan de Fuca plate, coloured by distance from the ridge axis.

 

Schematic figure of melt distribution beneath a mid-ocean ridge, and the accompanying Qs and Vs profiles 'seen' by synthetic seismic rays arriving at seismometers on the seafloor. 


Useful links

None of these is my work...  I wanted to provide a selection of resources that I have found helpful and that I recommend you check out. 

 

Excellent article on "The Really Big One"  –  Pulitzer Prize winning New Yorker article by Kathryn Shulz on the potential consequences of a M9 earthquake in Cascadia. Aside from a taking a couple of liberties describing the extent of the damage, I think this is the most accurate and best-written 'popular' Earth Science article I've ever read.

USGS latest earthquakes page  –  Nice interactive map with recent large earthquakes worldwide. Filter the data by time and magnitude and select events on the left panel to drill down into the many data products available through this portal, including tectonic summaries,  moment tensors,  waveforms, and much more. 

Temblor earthquake hazard estimator  –  Be forewarned! This fantastic and informative tool helps you understand seismic hazard in your area and provides tools to help you think about retrofitting and earthquake insurance.  If you live in California, this is VERY relevant and deserves your serious attention.

        For seismologists:

GCMT catalog search  –  Catalog of large (M>5.5ish) globally recorded earthquakes collated by the Global Centroid Moment Tensor project. 

International registry of seismography stations  – Complete registry of operational seismographic stations, maintained by the International Seismological Centre.

IRIS DMC Network List - Aggregated list of all seismic network codes (with description) that have data available through the Data Management Center, including virtual networks that group stations in some relevant way (e.g. GSN, US Transportable Array, OBSIP stations)