Apr. 13, 2012: There was a large "boom" felt in San Diego. My preliminary analysis is presented here here.
Dec. 23, 2011: "Acoustic Ray Tracer, 2D" or "ART2D" has been released. Check out the link here.
Dec. 13, 2011: My USArray work has been published. Many thanks to JGR Solid Earth and two anonymous reviewers for helping this go to press so quickly. Click here for the paper.
Jan. 13, 2011: UCSD infrasound arrays are detecting microbaroms coming from the eastern Pacific Ocean. CLICK HERE FOR AN OCTOBER 2011 UPDATE or HERE FOR A JANUARY 2012 UPDATE. Each of the arrays comprise several infrasonic microphones separated by several hundred meters. Pressure signals generated just above the ocean surface, likely from beating due to interfering opposing swells, travel great distances through the atmosphere. These signals are detected by each of the sensors in the arrays. Array processing identifies the direction from which the signals originated (back azimuth). We project these back azimuths outward from these arrays to form an intersecting back azimuth density color map, where reds indicate high densities. The color map has been converted to signal-to-noise ratio. The black contour is the statistical 95% confidence region for a model where there is only one source to explain all the detections at the arrays. The OFIS CHIAR array provided results that were consistent with those of the other arrays. This is the first time that the OFIS technology has been used for infrasound source physics research. Click here for a movie.
Assoc. Research Geophysicist
Inst. of Geophysics and Planetary Physics
Scripps Institution of Oceanography
University of California, San Diego
Contact info858-534-0126 (o)
Revelle 2000, Rm. 2110
9500 Gilman Ave., MC 0225
La Jolla, CA 92093-0225
8785 Biological Grade, Room 4114
La Jolla, CA 92037
Who Am I?
I'm a geophysicist interested in infrasonics, seismology, explosion monitoring, and interferometry. My general interest is in advancing our knowledge of Earth systems by adapting methods that are routinely used in well-developed communities to solve problems in emerging fields, especially problems that involve extensive computational resources. I have experience in managing research projects, designing arrays of geophysical instruments, and collaborating with researchers, engineers, and students. I also am experienced in writing white papers and proposals. I've published my work in 20 peer-reviewed papers and ∼60 abstracts (7 of them being invited). Lastly, I'm a reviewer of journal manuscripts and proposals, convener of special sessions at conferences, and member of SIO committees.
Curriculum Vitae [PDF]
- 2013-current: Assoc. Research Geophysicist, IGPP, Scripps, Univ. of California, San Diego
- 2009-13: Asst. Project Scientist, IGPP, Scripps, Univ. of California, San Diego
- 2005-06: Cecil & Ida Green Scholar, IGPP, Scripps, Univ. of California, San Diego
- 2004-09: Postdoctoral Researcher, IGPP, Scripps, Univ. of California, San Diego
Walker, K. T., A. Le Pichon, T. S. Kim, C. de Groot-Hedlin, Il.-Y. Che, and M. Garcés (2013), An analysis of ground shaking and transmission loss from infrasound generated by the 2011 Tohoku earthquake, J. Geophys. Res. Atmos., 118, doi:10.1002/2013JD020187.
de Groot-Hedlin, C., Hedlin, M., and Walker, K. T., 2013, Detection of gravity waves across the USArray: A case study, Earth Planet. Sci. Lett., doi:10.1016/j.epsl.2013.06.042.
DeWolf, S., Walker, K. T., Zumberge, M. A., and Denis, S., 2013, Efficacy of spatial averaging of infrasonic pressure in varying wind speeds, J. Acoust. Soc. Am., 133, 3739-3750, doi:10.1121/1.4803891.
Walker, K. T., 2012, Evaluating the opposing-wave interaction hypothesis for the generation of microbaroms in the eastern North Pacific, J. Geophys. Res, 117, C12016, doi:10.1029/2012JC008409.
Hedlin, M., and Walker, K., A study of infrasonic anisotropy and multipathing in the atmosphere using seismic networks, Phil. Trans. R. Soc. A , 371:20110542; doi:10.1098/rsta.2011.0542.
Hedlin, M.A.H., Walker, K., Drob, D. and de Groot-Hedlin, C.D., 2012, Infrasound: Connecting the Solid Earth, Oceans and Atmosphere, Annu. Rev. Earth Planet. Sci., 40, 327-354.
Walker, K.T., Shelby, R., Hedlin, M., de Groot-Hedlin, C., and Vernon, F., 2011, Western U.S. Infrasonic Catalog: Illuminating infrasonic hot spots with the USArray, J. Geophys. Res., 116, B12305, doi:10.1029/2011JB008579.
de Groot-Hedlin, C., Hedlin, M., and Walker, K., 2011, Finite difference synthesis of infrasound propagation through a windy, viscous atmosphere: application to a bolide explosion detected by seismic networks, Geophys. J. Int., doi: 10.1111/j.1365-246X.2010.04925.x.