7.1.1 The application of an inverse analysis

Urauchi Bay shows the oscillation resemble to a T-type harbor, with antinodes at

In order to study the damping process of oscillation in the T-type harbor shown in Figure 31, we continuously give incident waves to obtain a quasi-steady state of harbor oscillation, after which the incidence of waves is stopped when t = 0.0 s. Figure 35 shows the time variations of the maximum water level at point A indicated in Figure 31, during the damping of harbor oscillation for the first, second, and third modes after t = 0.0 s. The wave period of the incident waves,T, for the first, the second, and the third modes are 1150, 650, and 300 s, respectively, based on Figure 32. The damping of the oscillation for the second mode is slower than that for both the first and the third modes, because part of wave energy is trapped in the

Conversely, Figure 36 shows the time variations of the maximum water level at Oshima and Kuwanoura Fishing Ports facing Urauchi Bay shown in Figure 1. The wave period of the incident waves,T, is 1600 s for near the first mode, and 720 s for the second mode, based on Figure 33. The first-mode oscillation remains longer than the second-mode oscillation, which is not applicable to the T-type harbor mentioned above. Although future work is required to make this reason clear, we can tell the following difference between an actual bay and a typical T-type harbor:

The time variations of the maximum water level at point A in the T-type harbor shown in Figure 31, for the

The time variations of the maximum water level at Oshima and Kuwanoura Fishing Ports facing Urauchi Bay shown in Figure 1. The wave period of the incident waves,T, is 1600 s for near the first mode, and 720 s for the

6.7.3 The damping processes of oscillations in the T-type harbor and Urauchi Bay

two heads and a node at near the bifurcation.

Natural Hazards - Risk, Exposure, Response, and Resilience

second-mode oscillation between two harbor heads.

harbor oscillation of the first, the second, and the third modes.

Figure 35.

Figure 36.

102

second mode, based on Figure 33.

We discuss disaster measures against meteotsunamis, generated to propagate toward the west coasts of Kyushu. In order to predict the generation and propagation of meteotsunamis in real time, it is necessary to obtain atmospheric-pressure variation far from Kyushu. If we know the sites, concerning the generation of meteotsunamis through atmospheric-pressure variation, the valuable information on atmospheric pressure is restricted, such that the following inverse analysis is available:


According to the real-time variation in atmospheric pressure at the important sites, we can pick up bays and ports, which involve the risk of meteotsunami attack, to make adequate preparations for the meteotsunamis over a few days.

Conversely, we can also utilize a pattern recognition system for atmosphericpressure distributions, instead of the inverse analysis, to exemplify dangerous atmospheric-pressure patterns.
