My name is Hannah Mark, and I am a PhD student in the MIT-WHOI Joint Program in Oceanography/Applied Ocean Science and Engineering studying marine geology and geophysics.
I am interested in seismology, fault mechanics, plate boundary processes, and the structure and evolution of oceanic lithosphere. Below are a few current and past projects:
Pacific upper-mantle anisotropy from NoMelt
Analyzing active source data recorded by an OBS array. Mantle refraction travel times show upper mantle seismic velocities vary with azimuth. Azimuthal anisotropy is the result of the alignment of olivine crystals in a crystal-preferred orientation during corner flow at mid-ocean ridges.
Rate and state friction models of oceanic normal faults
Frictional properties on fault surfaces depend on slip velocity (rate) and slip history (state). Rate and state friction models can be used to simulate earthquake cycles on faults and explore the parameter space (fault geometry, thermal gradients) controlling seismic coupling and moment release rates.
Modeling seismic reflection imaging for steeply-dipping faults near subduction zones
Lineations on the ocean floor are the surface expression of bending-related faults near subduction zones. Such faults, as permeable pathways for fluid flow, have implications for the fluid budgets of arc volcanoes. However, high angle faults are difficult to image using seismic reflection. Synthetic seismograpms allow us to test whether we should be able to see such faults at depth in seismic images.
Wavelength-dependence of emissivity for shock-compressed iron
Temperatures of shock-compressed materials have been measured using spectral radiance. The wavelength dependence of emissivitiy must be taken into account for calculations of temperature from optical measurements. Reanalyzing the data of Bass et al.  with wavelength-dependent emissivity gives a high-pressure melting temperature for iron that agrees with other experimental and theoretical results. This work was done with Dion Heinz at the University of Chicago.
A general-audience view of a chunk of my thesis research can be found in the 2018 student issue of Oceanus: How is the seafloor made?
I've also written a few short pieces for my program's student blog:
- The erstwhile king of Siluria
- A brief history of the Wide Receiver Functions
- Harry Potter and the 12-minute conference talk
- SCARF 2017 cruise recap
You can occasionally find me writing even shorter science-related things on twitter @tellurianite.
Grad school occupies the vast majority of my time, but even PhD students occasionally do things other than read papers and debug code. I imagine that it would be difficult to stay sane without some hobbies. Mine include running, quilting, baking, playing carillon, librarian-ing, and choral singing. I'm always happy to talk about bells, pie crust, Renaissance choral music, or the merits of the Dewey Decimal system with anyone who cares to listen.
hmark (at) whoi.edu
Woods Hole Oceanographic Institution
266 Woods Hole Road, MS #24
Data files for WHOI Summer Math Review exercises:falmouth_temp