Research

Fluid-driven fractures shape glaciers, volcanoes, geothermal reservoirs, carbon-storage systems, and engineered subsurface operations. Yet many fracture theories are still tested mainly against laboratory experiments, idealized models, or indirect observations. The group uses controlled field experiments, dense sensing, and mechanics to test how pressure, elasticity, freezing, heterogeneity, and boundaries control crack growth and arrest.

Controlled experiments and fracture resonance

Vibrations generated within a fluid-filled crack provide a direct connection between measurable wavefields and otherwise hidden fracture properties. Early work showed how resonance can constrain crack geometry, fluid properties, and coupled fluid–solid response [2]. Current experiments build on that framework by combining controlled pressure forcing with dense measurements of deformation and radiated waves.

Growth, arrest, and freezing

A central question is how a fracture transitions from initiation to sustained growth or arrest. In ice, freezing adds a thermomechanical feedback: the fluid that drives a crack can also freeze, change its pressure and compliance, and alter the conditions for propagation. Field observations and mechanical models are being developed to test how this feedback changes hydrofracture and ice-sheet stability. Related work couples ice flow, flexure, and fracture to resolve how cracking alters shelf-scale evolution [32].

Fluid–fracture coupling at full scale

Ice-shelf rifts provide a large-scale test of the same mechanics. Observations show that the surrounding ocean limits rupture velocity, while tides and ocean waves supply time-dependent loading that can trigger or regulate propagation [24, 6]. These systems connect controlled experiments to fractures that span an entire floating ice shelf.

Glaciers and ice sheets are natural laboratories where fracture, friction, and deformation can be observed over scales that are inaccessible in conventional experiments. Their behavior is governed by boundaries: where ice meets rock, water, ocean, and atmosphere. The group combines mechanical models with seismic, fiber-optic, remote-sensing, and field observations to test how these interfaces control failure and stability.

Ice-shelf rifts and calving

Ice-shelf rifts are the largest fractures in glacier systems. Mechanics-based models and observations constrain when they remain stable, when they propagate, and how geometry, tides, ocean swell, temperature, flexure, and shear margins alter rupture [13, 11, 14, 18].

Glacier-bed friction

A series of studies showed that basal icequakes are best explained by rock-on-rock grinding rather than ice sliding directly over rock or sediment [3, 5, 10, 15, 16, 19]. A full-thickness fiber cable frozen into Store Glacier now provides a direct view of time-varying basal friction [21].

Calving and ice–ocean coupling

Seafloor observations in Greenland showed that iceberg calving generates internal waves and fjord circulation that enhance submarine melting. The Nature study, led by postdoctoral scholar Dominik Gräff, identified calving as an active source of ocean mixing rather than only a response to ocean forcing [31]. At the global scale, work led by former student Simon-Hans Edasi showed how marine-terminating geometry links ice-cliff mechanics to glacier thickness and stability [35].

Slow deformation and ancient ice

At the other end of the rate spectrum, the group studies how multimillion-year-old ice survives in the Allan Hills of Antarctica. Microstructure, ice flow, thermodynamics, and boundary interactions constrain both deformation of the archive and the pathways by which very old ice can be preserved [38].

Fiber sensing is the observational platform that makes many of these field tests possible. Distributed acoustic and temperature sensing turn cables into dense measurements of strain, strain rate, temperature, and wave propagation, allowing mechanical theories to be tested in systems that are otherwise inaccessible.

The measurement principle is that light changes as it travels through an optical fiber in ways that depend on the cable’s mechanical and thermal state. Distributed Acoustic Sensing (DAS) records dynamic strain or strain rate, while Distributed Temperature Sensing (DTS) resolves temperature. Measurements can be made every few meters along cables extending roughly 100–150 kilometers—and farther when existing telecommunications infrastructure can be used [34].

Field experiments, laboratory calibration, theory, and comparisons with broadband seismometers have established when DAS can be interpreted as a dense array of one-component strain seismometers [28]. The group also develops data compression, reconstruction, wavefield separation, and edge-computing methods so that large fiber datasets retain the signals needed to test mechanics [23, 26].

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These collaborations extend the same field-mechanics approach to earthquake source physics, volcanic deformation, offshore sensing, geothermal systems, and monitoring applications [1, 7, 12, 27]. The questions remain mechanical: where deformation localizes, how rupture develops, and what dense wavefields reveal about structure and forcing.

Current projects include volcanic systems such as Mount Rainier, Cordón Caulle, and Yellowstone; ocean-wave and shallow-seafloor observations; and hybrid fiber–seismic monitoring through Brad’s joint appointment at Pacific Northwest National Laboratory [29, 37].

Controlled field tests of fluid-driven fracture

A central direction is to measure pressure, deformation, and radiated wavefields while fractures initiate, grow, and arrest. These observations will test how elastic response, heterogeneity, and boundaries determine fracture evolution, building on earlier work that connects fracture resonance to geometry and fluid state [2].

Freezing, hydrofracture, and ice-sheet stability

Field observations and mechanical models will test how freezing within a water-filled crack changes pressure, compliance, and propagation. This direction extends models that couple ice flow, flexure, and fracture [32] and has parallels in magma transport, geothermal systems, and carbon storage.

Ice-shelf–ocean coupling

A planned 2027–28 Antarctic deployment will observe ice-shelf–ocean interaction directly, treating the ocean as part of the fracture system rather than as external forcing alone. The work builds on evidence that ocean coupling limits rift rupture and that calving drives circulation and melt [24, 31].

Pressure sensing and ice deformation

Deep, frozen-in pressure sensors may resolve small changes in overburden and surface mass balance. The experiment tests whether deformation and pressure at depth can provide a direct, high-resolution record of ice-sheet mass change [4, 17].