Construction of Quasi-Real-Time Observation System for Earthquakes at (Uninhabited) Islands and Its Experimental Observation

建立了包括无人地震在内的海岛地震准实时观测系统。对于现有地震台网检测到的所有地震，观测波形数据通过卫星移动电话从地震台自动采集到观测站。该系统由地震台设备和观测站控制软件组成。请求命令(起始时间、时间窗口长度和波形数据的分量)在观测站参考现有网络系统中的触发信息发出并发送到站。在地震台，观测数据被连续记录在数据记录仪上，其中的时钟由GPS管理。在接收命令时，将连续记录中的切割数据付诸实施，并将提取的数据与电源、GPS时间校正和设备内部温度的日志文件一起传输到天文台。电力由太阳能和汽车电池提供。例如，为了节省电力，只有在与天文台通信的预设时间才向卫星移动电话供电。设备的特点之一是具有自恢复功能，大部分工作在缺电时停止，充电后重新启动。这有利于免维护。本系统的实验观测是在日本托卡拉群岛南端的无人居住的横滨-吉马岛上进行的。实验结果表明，该系统运行良好，具有实际应用价值。

Quasi-real-time system for observation of earthquakes at island including uninhabited one was constructed. The observed waveform data are collected to observatory from seismic station by satellite mobile phone automatically for all the earthquakes detected by the existing seismic network. This system is composed by the equipment at seismic station and the controlling software at observatory. The command of request (onset time, length of time window and component of waveform data) is made at observatory on referring to the triggered-information in the existing network system and is sent to station. At seismic station, the observed data are recorded continuously on data logger, in which the clock is managed by GPS. Cutting data from the successive records is put into practice at the reception of the command and the extracted data are transmitted to observatory together with the log-files of power supply, time correction by GPS and temperature within the equipment. The power is supplied by solar and car batteries. For saving power, for example, it is supplied to satellite mobile phone only at the preset time of communication to observatory. One of the characteristics of equipment is the function of self-recovery, the greater part of works stop at the shortage of electric power and restart when the power is recharged. This is advantageous for maintenance free. Experimental observation of the present system was carried out at the uninhabited island, Yokoate-jima, at the southern, end of Tokara-islands, Japan. This experiment was operated well and the present system was confirmed to be valuable for practical usage.