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 computational geophysicist with expertise in reflection seismology, earthquake seismology, explosion seismology, acoustics, potential fields, and interferometric sensing. My passion is using computers to solve large problems. I typically do this in the form of software development for the purposes of multi-dimensional array processing of massive data sets, data modeling, data mining, and uncertainty quantification. I'm experienced in project management from the stages of proposal writing to the publication of results. I've published 23 refereed papers and more than 60 abstracts/reports. My diverse research background has provided me with the experience necessary to efficiently cross disciplines, as well as a knowledge base from which I routinely adapt and improve techniques to solve problems in emerging fields.
2004: Stanford University, Ph.D., Teleseismic Seismology (Thesis)
2000: Stanford University – M.S., Active-source Seismology
1998: University of Delaware – B.S. w/ Distinction, Geophysics, Cum Laude (Thesis, Plates 1/2, Plates 3/4, Plate 5, Plates 6/7, Plate 8) )
- 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. [web, pdf]
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. [web, pdf]
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. [web, pdf]
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. [web, pdf]
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. [web]