# Realtime Tsunami Prediction System Using Ocean Floor Network for Local Regions
## 3 Implementation of the Prediction System  
### System Specification  
We considered that the system should be basically simple. The main tasks of the prediction system are receipt of data, management of the database, production of tsunami prediction data, and visualization. One server handles all these tasks (Figure 9). If local governments and companies are users of the system, the cost of implementation needs  
Figure 8: Examples of S-net records after processing of STA, LTA, and VLTA, and add a profile of the ratio of STA and LTA. (**Upper**) Pressure gauge data of S1N01 observatory with much noise. (**Middle**) S1N02 observatory with good quality. (**Lower**) S2N06 observatory with long frequency noises.  
to be low. In Japan, users have to obtain permission from the JMA to transmit predicted tsunami information to other organizations. We consider that the task burden and database should be as small as possible. For this reason, we reduced the number of fault models as described in Section 2.3. Many users can connect to the server installed in our tsunami prediction application as clients using a PC.  
We included many mechanisms to avoid various types of problems. For example, the 2011 earthquake off Tohoku cut some seafloor transmission cables off the Boso area. If the backbone cables had been cut on the seafloor, it would have been difficult to continue to predict tsunamis. Users should know the condition of the ocean floor network system in real time. Therefore, we prepared a monitoring system of seismometers and pressure gauges to detect waveforms in real time. We have asked users to check waveforms in real time when earthquakes and tsunamis are triggered.  
How the predicted information is distributed can also be controlled. Some users want to control it using the JMA tsunami warning system, so such a switch has been installed in our system. Users may sometimes want to use their mobile devices to inform residents along a coastal area that a tsunami is coming. The system can be expanded to incorporate a variety of inputs that control the distribution of data and to output data to many types of devices.  
The topography around the predicted point of landfall can be changed by construction projects, such as the replacement of breakwaters, renovation of fishery ports, and introduction of tetrapods to prevent erosion by ocean currents. In such cases, part of the tsunami database should be updated to maintain its accuracy. The prefecture can collect such construction information, and the prefecture itself can replace the database by recalculating the tsunami waveforms. Easy updating of the tsunami database is also one of the issues to be taken into consideration.  
Figure 9: Example for social implementation of this system. Input data is observed data from seismometers and pressure gauges of the ocean floor network system, and tsunami warning from JMA to control the distribution of tsunami prediction information. Inside the same organization and from the outside, clients can access the server.  
We have already implemented this system for some organizations. Many of them have prepared two systems to ensure redundancy. For example, some organizations use one of them for real-time prediction and the other for evacuation drills. We have prepared an option for evacuation drills that enables users to send calculated waveforms for seafloor observatories and the predicted points of landfall to the system as real-time input data. Users can select arbitrary waveforms using many fault models, for example, the Nankai fault models with M9 [23].