Brent Delbridge Brent Delbridge
Email: bdelbridge@fas.harvard.edu
Postdoctoral Fellow

Harvard Seismology Group
Department of Earth and Planetary Sciences
Harvard University


Download CV
Research Interests

My research focuses on developing new tools and constraints to evaluate mathematical models of physical processes and Earth structures. I am currently working to develop new theoretical and observational frameworks to utilize the information about earthquake source processes and Earth structure contained within long-period recordings of seismic energy.

1) Seismological constraints of the the Inner core

The inner core, plays a crucial role in our planet’s formation and evolution, as well as powering the Earth’s magnetic field that protects life from harmful cosmic rays. Despite its importance, it is the least well understood of the Earth’s interior. Its remote location (more than 5000 km below ground) and harsh environment( high T-P) make it difficult to simulate in the laboratory or computer simulation, and we must rely upon information collected at the Earth’s surface. When large earthquakes occur, they cause the Earth to ring like a bell and by observing and listening to these sounds, we have determined that the inner core is solid iron, and it is surrounded by the outer core which is liquid iron. However, the liquid outer core isolates the inner core, obscuring our understanding of the detailed structure and composition of the Earth’s inner core. We are currently working to develop new methods to circumvent the obstacles posed by the Earth’s liquid outer core to better determine the inner core structure and composition. We are investigating issues with and limitations of current seismological constraints, especially in light of comparison with mineral physics constraints, and how to resolve these observational biases to better constrain the inner-core composition.

2) Seismological constraints on Surface Rupture

Current techniques used to determine whether slip reached the seafloor in submarine earthquakes are expensive and cannot be applied generally to all earthquakes of interest. This lack of observations has hindered the scientific community's understanding of the physical conditions controlling rupture of the shallowest part of the plate interface which result in displacement of the seafloor and increased likelihood of generating a significant tsunami. We are currently developing a theory to determine whether or an earthquake rupture reached the surface and distinguish events for which slip reached and did not reach the surface using long-period seismology (normal modes and long-period surface waves). A simple methodology, which uses the amplitude of excited modes modes (or equivalently specific period bands within surface waves), has been developed and can be used to indicate the presence of surface rupture. Armed with this new diagnostic tool and observations from current and historical seismic networks (e.g., WWSSN, GSN) it should be possible to imporove our current understanding of the physical mechanisms controlling submarine surface rupture by vastly increasing the number of observation of surface rupture - this includes important events such as the 2011 Tohoku, 2004 Sumatra, and 2010 Chile earthquakes as well as the 1964 Alaska earthquake.


Education

2017 Ph.D. (Earth and Planetary Science), University of California, Berkeley, CA

2011 B.Sc. & B.Sc. (Physics & Applied and Computational Mathematical Sciences), University of Washington, Seattle, WA


Professional Experience

2017 Postdoctoral Fellow, Harvard University, Cambridge, MA

2013 GROW Visiting Research Fellow, Tohoku University RCPEVE, Sendai, Japan




Brent Delbridge

Publications

Delbridge, B., Nadeau, R., Bürgmann, R, (2017). Geodetic Signature of Slow-Slip and Tremor in Parkfield, CA, J. Geo-phys. Res. Solid Earth. (In Prep.)

Delbridge, B., Kita, S., Houston, H., Bürgmann, R., (2017). Variations in intraplate stress Beneath NE Japan following the 2011 Tohoku-oki Eathquake from Earthquake Focal Mechanisms, Geophys. Res. Lett. (In Prep.)

Nelson, O., Delbridge, B., Mittal, T., Randolph-Flagg N., Manga, M. 2017. Internal Flow Dynamics of Dikes in Analog Experiments and Their Controls on Magma Ascent Processes, Geophys. Res. Lett. (In Prep.)

Mittal, T. Delbridge, B., (2017). Global detection of submarine eruptions using the Argo data set and its implications for ocean dynamics, Submitted.

Saltiel, S., Bonner, B., Mittal, T., Delbridge, B., Ajo-Franklin, J. (2017). Stress-strain hysteresis loops and harmonics show rate-dependent nonlinearity of mated dolomite fracture. J. Geophys. Res. Solid Earth, 122, doi:10.1002/2017JB014219.

Delbridge, B., Johnson, C.W., Kita, S., Matsuzawa, T.,Uchida, N.,Bürgmann, R., (2017). Temporal variation of intermediate-depth earthquakes around the time of the M 9.0 Tohoku-oki earthquake. Geophys. Res. Lett., 44, doi:10.1002/2017GL072876.

Delbridge, B., Bürgmann, R., Fielding, E., Hensley, S. and Schulz, W.H., (2016). Three-dimensional surface deformation derived from airborne interferometric UAVSAR: Application to the Slumgullion Landslide. J. Geo-phys. Res. Solid Earth, 121, 3951–3977, doi:10.1002/2015JB012559.

Delbridge, B., Bürgmann, R., Fielding, E. and Hensley, S., (2015), July. Kinematics of the Slumgullion Landslide from UAVSAR derived interferograms. IGARSS (pp. 3842-3845). IEEE.

Birch, S.P.D., Manga, M., Delbridge, B. and Chamberlain, M., (2014). Penetration of spherical projectiles into wet granular media. Physical Review E, 90(3), p.032208.

Milillo, P., Fielding, E.J., Shulz, W.H., Delbridge, B. and Bürgmann, R., (2014). COSMO- SkyMed spotlight interferometry over rural areas: The Slumgullion landslide in Colorado, USA. IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, 7(7), pp.2919-2926.

Knecht, A., Hong, R., Zumwalt, D.W., Delbridge, B., Garcia, A., Müller, P., Swanson, H.E., Towner, I.S., Utsuno, S., Williams, W. and Wrede, C., (2012). Precision measurement of the 6 He half-life and the weak axial current in nuclei. Physical Review C, 86(3), p.035506.

Houston, H., Delbridge, B., Wech, A.G. and Creager, K.C., (2011). Rapid tremor reversals in Cascadia generated by a weakened plate interface. Nature Geoscience, 4(6), pp.404-409.

Knecht, A., Zumwalt, D.W., Delbridge, B., Garcia, A., Harper, G.C., Hong, R., Müler, P., Palmer, A.S.C., Robertson, R.G.H., Swanson, H.E. and Utsuno, S., (2011). A high-intensity source of 6 He atoms for fundamental research. Nuclear Instruments and Methods in Physics Research, 660(1), pp.43-47.

Freeman, B.M., Wrede, C., Delbridge, B., Garcia, A., Knecht, A., Parikh, A. and Sallaska, A.L., (2011). Branches of S 33 (p, γ) at oxygen-neon nova temperatures. Physical Review C, 83(4), p.048801.

Department of Earth and Planetary Sciences / Harvard University / 20 Oxford Street / Cambridge / MA 02138 / U.S.A. / Telephone: +1 617 495 2350 / Fax: +1 617 496 1907 / Email: reilly@eps.harvard.edu