Electronic Supplement to
A seiche hazard study for Lake Union, Seattle, Washington
by A. Barberopoulou
Evolution of wave propagation into the Lake Union basin
These four figures show the propagation of water waves in Lake Union after the initiation of various types of ground shaking. There are four types of ground shaking used for the figures below. For the first two (Figure 2, Figure 3) we used simple sinusoidal forcing of period 100 seconds in the EW and NS directions correspondingly. Figures 5 and 8 (Figure 5, Figure 8) contain true ground motion recordings from the Mw7.9 Denali, Alaska earthquake of 3 November, 2002, the M6.8 2001 Nisqually earthquake and the Japanese Mw8.0 Tokachi-oki subduction zone earthquake of September 2003 (seismic data courtesy of the Kyoshin Network of Japan).
Figures and Animations
Figure 2. Snapshots of waveheights in Lake Union taken at 50 second intervals up to 300 seconds after the initiation of ground shaking. The lake is forced with a sinusoidal forcing (100 seconds period and amplitude 0.01m/sec2) in the east-west direction (x-axis). The time step used was 1/10 of a second. Red corresponds to crest of wave and blue to trough. Amplitudes of waves in the colorchart are in meters.
A movie corresponding to this scenario (Lake Union forced at 100 seconds period in the East West direction) follows next:
Figure 3. Snapshots of waveheights in Lake Union taken at 50 second intervals up to 300 seconds after the initiation of ground shaking. The lake is forced with a sinusoidal forcing (100 seconds period and amplitude 0.01m/sec2) in the north-south direction (y-axis). The time step used was 1/10 of a second. Red corresponds to crest of wave and blue to trough. Amplitudes of waves in the colorchart are in meters.
A movie corresponding to this scenario (Lake Union forced at 100 seconds period in the North South direction) follows next:
Figure 5. Top. Snapshots of Lake Union taken at 15 second intervals up to 60 seconds after the initiation of Nisqually ground shaking. The lake is forced with the WISC station recordings (both NS and EW components of ground motions;fig.6). Bottom. Snapshots of Lake Union taken at 50-150 seconds after the initiation of Denali ground shaking. The lake is forced with the WISC station recordings (both NS and EW components from the Denali earthquake; fig.4). The time step used was 1/10 of a second. Red corresponds to crest of wave and blue to trough. Amplitudes of waves in the colorchart are in meters.
Figure 8. Snapshots of Lake Union taken at 50 second intervals up to 200 seconds after the initiation of ground shaking. The lake is forced with both NS and EW components from a subduction zone earthquake recording made in Japan from the M8.0 Tokachi-Oki earthquake of 2003 (see fig.8). The time step used was 1/10 of a second. Red corresponds to crest of wave and blue to trough. Amplitudes of waves in the colorchart are in meters.
A movie corresponding to this scenario (Lake Union forced with Tokachi-Oki earthquake ground motion records) follows next:
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