Earthquake ground motions have been observed at the New A Runway, the Sky Arch, the New B Runway and a railroad tunnel at Haneda Airport. The Port and Airport Research Institute have been in charge of collection and analyses of the data. Through the analyses of the data, the authors would like to retrieve a wide range of technical information which would play a vital role in the future construction of facilities not only at this particular airport but also at other airports which are located on soft soil layers.
　In the present technical report, as the first step of the research, the authors investigate the basic characteristics of surface waves (back azimuth, phase velocity and wave length) at this particular airport. These characteristics have significant effects on the seismic performance of long structures such as runways, submerged tunnels and pipelines because the ground motions acting on various parts of a long structure show phase difference, which is mainly due to the transmission of surface waves in case without significant horizontal heterogeneity. In the present report, F-K analysis is applied to the array records at the New A Runway to examine the characteristics of surface waves.
　As a result of the analyses, it was revealed that the phase velocity of the fundamental-mode Love wave, which has the shortest wave length among various surface waves here at Haneda Airport and hence which is the most dangerous from the structural safety point of view, is approximately 400m/s at the period of one second and approximately 750m/s at the period of 3 seconds. Accordingly, its wave length is approximately 400m at the period of one second and approximately 2250m at the period of 3 seconds. It should be noted that these values may become even smaller if the ground show a non-linear behavior during large earthquakes. The observed dispersion curve agrees well with the theoretical one obtained from a subsurface structure based on conventional articles.