HR: 0800h
AN: S31A-0269    [Abstracts]
TI: Extracting the response of a building with seismic interferometry
AU: * Snieder, R
EM: rsnieder@mines.edu
AF: Center for Wave Phenomena and Dept. of Geophysics, Colorado School of Mines 1500 Illinois Str., Golden, CO 80401 United States
AB: The motion of a building depends on the excitation, the coupling of the building to the ground, and the mechanical properties of the building. I separate the building response from the excitation and the ground coupling by deconvolving the motion recorded at different levels in the building, and apply this to recordings of the motion in the Robert A. Millikan Library in Pasadena, California. The waveforms obtained from deconvolution with the motion in the top floor show a superposition of one upgoing and one downgoing wave. The waveforms obtained by deconvolution with the motion in the basement can be formulated either as a sum of upgoing and downgoing waves, or as a sum over normal modes. Since these deconvolved waves for late time have a monochromatic character, they are most easily analyzed with normal-mode theory. For this building I estimate a shear velocity c=322 m/s and a quality factor Q=20. These values explain both the propagating waves as well as the normal modes. I show for this application of seismic interferometry that deconvolution of waveforms is superior to correlation.
DE: 7212 Earthquake ground motions and engineering seismology
DE: 7260 Theory
SC: Seismology [S]
MN: Fall Meeting 2005