Abstract Finite-frequency travel time tomography is a newly developing method. The main procedure in this new method is to compute the traveltime sensitive kernel. The travel time of the same scatterer needs to be used for computing the traveltime sensitive kernel many times. It is a time-consuming task. It is easy and fast to get the travel time from analytic equations in a simple model such as a homogenous or linear velocity media. However, most of the earth models are layered. It is cumbersome to get the travel time from analytic equations. In order to enhance the computation effi ciency, we used the table look-up method to compute the finite-frequency travel time sensitive kernel for P-waves in a layered structure model. We chose the AK135 earth model for the velocity model. The table look-up method saved about 50% of the computation time. We enhanced the computation speed by using the table lookup method in the same velocity model, which was very useful for enhancing the computation effi ciency for the fi nite-f equency travel time tomography.
This research is supported by the National Natural Science Foundation of China (Grant No. 90814013).
About author: Zhang Feng-Xue, obtained his bachelor degree from the Ocean University of China in 2006. Now he is studying successive postgraduate and doctoral programs at the Institute of Geophysics, China Earthquake Administration. His PhD thesis interests include seismic tomography and raytracing.
Cite this article:
ZHANG Feng-Xue,WU Qing-Ju,PAN Jia-Tie et al. The computation of a finite-frequency travel time sensitive kernel for P-waves in the AK135 earth model[J]. APPLIED GEOPHYSICS, 2011, 8(2): 158-163.
[1]
Aki, K., and Lee, W. H. K., 1976, Determination of three-dimensional velocity anomalies under a seismic array using first P arrival times from local earthquakes 1. A homogeneous initial model: J. Geophys. Res., 81(23), 4381 ? 4399.
[2]
Capdeville, Y., 2005, An efficient Born normal mode method to compute sensitivity kernels and synthetic seismograms in the Earth: Geophys. J. Int., 163, 639 ? 646.
[3]
Dahlen, F. A., Hung, S. H., and Nolet, G., 2000, Fréchet kernel for finite-frequency traveltimes －Ⅰ. Theory: Geophys. J. Int., 141, 157 ? 174.
[4]
Huang, J. L., and Zhao, D. P., 2004, Crustal heterogeneity and seismotectonics of the region around Beijing, China: Tectonophysics, 385, 159 ? 180.
[5]
Huang, J. L., and Zhao, D. P., 2006, High-resolution mantle tomography of China and surrounding regions: J. Geophys. Res., 111(B09305).
[6]
Hung, S. H., Dahlen, F. A., and Nolet, G., 2000, Fréchet kernels for finite-frequency traveltimes －Ⅱ. Examples: Geophys. J. Int., 141, 175 ? 203.
[7]
Hung, S. H., Dahlen, F. A., and Nolet, G., 2001, Wavefront healing: a banana-doughnut perspective: Geophys. J. Int., 146, 289 ? 312.
[8]
Hung, S. H., Shen, Y., and Chiao, L. Y., 2004, Imaging seismic velocity structure beneath the Iceland hot spot: A finite frequency approach: J. Geophys. Res., 109(B08305).
[9]
江燕, 广义走时有限频层析成像:博士论文,北京大学, 2009.
[10]
Kennett, B. L., Engdahl, E. R., and Buland, R., 1995, Constraints on seismic velocities in the Earth from traveltimes: Geophys. J. Int., 122, 108 ? 124.
[11]
Liu, Q., and Tromp, J., 2006, Finite-Frequency Kernels Based on Adjoint Methods: Bull. Seism. Soc. Am., 96(6), 2383 ? 2397.
[12]
Moser, T. J., 1991, Shortest path calculation of seismic rays: Geophysics, 56(1), 59 ? 67.
[13]
Nolet, G., and Dahlen, F. A., 2000, Wave front healing and the evolution of seismic delay times: J. Geophys. Res., 105(B8), 19043 ? 19054.
[14]
Tromp, J., Tape, C., and Liu, Q., 2005, Seismic tomography, adjoint methods, time reversal and banana-doughnut kernels: Geophys. J. Int., 160, 195 ? 216.
[15]
Wessel, P., and Smith, W. H. F., 1995, New version of the generic mapping tools released: EOS Trans： AGU, 76(33), 329.
[16]
Zhao, D. P., Hasegawa, A., and Kanamori, H., 1994, Deep structure of Japan subduction zone as derived from local, regional, and teleseismic events: J. Geophys. Res., 99(B11), 22313 ? 22329.
[17]
Zhao, L., Jordan, T. H., and Chapman, C. H., 2000, Three-dimensional Frechet differential kernels for seismic delay times: Geophys. J. Int., 141, 558 ? 576.
[18]
Zhao, L., Jordan, T. H., Olsen, K. B., and Chen, P., 2005, Frechet Kernels for Imaging Regional Earth Structure Based on Three-Dimensional Reference Models: Bull. Seism. Soc. Am., 95(6), 2066 ? 2080.
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