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Crevassing in a shear margin

Ice Streams and the Physics of Meltdowns

The Antarctic Ice Sheet holds about 61% of all fresh water and is thus a crucial component in climate models. Observations indicate that Antarctica is warming, with most of the mass loss occurring in West Antarctica. The principal drainage routes for the inland ice are the West Antarctic ice streams - regions of several km width and hundreds of km length in which the ice flows more than an order of magnitude faster than in the surrounding ice ridges. Despite the importance of ice streams for the mass balance of West Antarctica, the mechanism that sets their width and flow speed is largely unknown. The goal of this project is to shed some new light on the thermal and fluid-dynamical processes that control the dynamics of ice streams. 
Collaborators: Jim Rice, Thibaut Perol, John D. Platt

Strombolian eruptions

Slug or Plug: Why does Stromboli volcano erupt?

Stromboli volcano is famous for its relatively mild but astonishingly persistent eruptions. The leading paradigm for these so-called normal eruptions posits that each eruption represents the burst of a large gas slug ascending through liquid magma in the volcanic conduit. Numerous petrological studies, however, have established the existence of drastic contrast in the crystallinity of the magma at shallow depth. These observations shed doubt on a purely fluid-dynamical view of the conduit dynamics at Stromboli. We suggest an alternative view of the mechanism of normal eruptions, which is based on the insight that the magma in the uppermost plumbing system is sufficiently crystalline to form a porous plug.  
Collaborators: Kathy Cashman, Isolde Belien, Brad Hager, Per Olof Persson

Map of the lunar surface

Crystals stirred not shaken

The lunar crust is thought to have formed through flotation of buoyant plagioclase crystals (which are apparent even from Earth due to their white color) at a time when the rocky mantle of the Moon was still largely molten. Despite the observational evidence in favor of this hypothesis, it remains unclear how plagioclase would have been able to float in a turbulently convecting magma ocean. To better understand crust formation on the moon, we couple the geochemical and fluid dynamical evolution of the lunar magma ocean and investigate under which conditions the mineral phases are able to settle and float. 
Collaborators: Lindy Elkins-Tanton, James Sethian, Jiun-der Yu

Tsunami hitting Natori City, Japan, March 11, 2011

Rethinking tsunami preparedness

The role of coastal forests in the mitigation of tsunami disasters has become a hotly debated topic in the aftermath of the devastating tsunami in the Indian Ocean in 2004 and Japan in 2011. Unfortunately, our knowledge of the interactions between tsunamis and vegetation is limited and the associated danger of ineffective or even potentially harmful policies is concerning. Through this project, we hope to contribute to bridging the gap between science and policy and provide new insights on whether and how coastal trees or forests may be promising for protective purposes.
Collaborators: Miho Mazereeuw

Injection model

Under the Macroscope: Constraining Spatiotemporal Characteristics of Triggered Seismicity at the Reservoir Scale Using Data-driven Models

One challenge facing triggered seismicity hazard assessment is an apparent lack of readily-available, strong predictors: it is difficult or expensive to obtain the necessary data to determine whether injection at a particular site is likely to induce earthquakes. Susceptibility to induced seismic activity is influenced by a host of site- and operation-specific parameters, such as ambient stress magnitudes, presence of faulting, and the volume of fluid injection. Modern machine learning techniques can help us make sense of these multi-dimensional spaces, first, by dividing the parameter space into discrete regions of seismic susceptibility and, second, by probing the functional (predictive) relationships between predictors and outcome.