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

建立了包括无人岛在内的海岛地震准实时观测系统。现有的地震台网所监测到的所有地震，其观测波形数据都是通过卫星移动的电话从地震台站自动采集到观测台的。该系统由台站设备和观测站控制软件组成。在观测站参考现有网络系统中的触发信息，发出请求命令（起始时间、时间窗长度和波形数据分量），并发送到台站。在地震台站，观测数据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，从连续记录中切割数据，并将提取的数据与设备内的电源、GPS时间校正和温度的日志文件一起传输到观测站。电力由太阳能和汽车电池提供。例如，为了节省电力，它只在与天文台通信的预定时间提供给卫星移动的电话。设备的特点之一是具有自恢复功能，大部分工作在电力不足时停止，并在电力补充时重新启动。这对于免维护是有利的。本系统的实验观测进行了无人居住的岛屿，横手岛，在南部，日本Tokara群岛的结束。实验结果表明，该系统具有较好的实用价值。

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.