William B. Durham: Research

Research themes

My students, colleagues, and I measure the strength of earth and icy planetary materials at high pressures and extreme temperatures (hot or cold). The work is mostly experimental and mostly done indoors. The overriding purpose of our experiments is to provide constraint for dynamic models--from deep interiors to near surface--anywhere that strength of materials comes into play. To say it another way, we reach out to any area of perceived relevance where the state of deviatoric stress is non-negligible. We currently concentrate in two areas:

Flow and fracture of water ice (including its high-pressure phases through ice VI), and of other frozen volatiles (such as methane, ammonia, carbon dioxide) to help constrain models of planetary dynamics and surface geology on Mars and icy satellites of the outer solar system.

(Click on the images for an enlarged view)

Flow of mantle rocks (especially olivine) to help us constrain the internal dynamics of our own planet. These experiments involve new kinds of deformation apparatus and the use of synchrotron x rays to measure stress and plastic strain.

Current research programs

"Laboratory Study of the Effects of Impurities on the Flow and Fracture of Icy Materials on Mars," 2011-2014, NASA [See proposal summary]

"Rheological Properties of Earth’s Upper Mantle at High Pressure: Roles of Melt, Water and Pressure," 2012-2015 (pending), Office of Science, Basic Energy Sciences, DOE [See proposal summary]

"Rheological behavior of icy mixtures with application to the outer planets," 2013-2016, NASA [See proposal summary]

Ressearch highlights (Click on the images)

	One two-phase icy mixture with important ramifications for the martian North Polar Layered Deposits is water ice + magnesium perchlorate hydrate (MP6). A small amount of MP6 has a big weakening effect on ice.			How much ice must be added to a frozen sand pack to make it unjam, and what might this tell us about water content of the martian megaregolith?
	The strength of two-phase icy mixtures during plastic deformation is a common theme of several of our recent projects.			Using the D-DIA, we have finally been able to measure the effect of overburden pressures on the creep of olivine (the prime component of Earth's mantle) at pressures > 2 GPa.
	Grain-size sensitive creep of high-pressure ice II			Grain size-sensitive vs. grain size-insensitive flow in ice I.
	Gas clathrate hydrates may appear "ice-like," but we have discovered that they are rock-hard.			New views of materials bring new questions. We we are starting to use numerical modeling to solve fresh problems in strength of materials.
	Not everything works the first time. Check out our attempt to measure the creep strength of solid nitrogen and other so-called "vander Waals solids."			Is the Mars south polar cap made of CO₂? Lab experiments come through again.
	Measuring rates of dissolution of methane and CO₂ clathrate hydrates in a seafloor laboratory