Systematic research on low-frequency tremor, "very" low-frequency earthquake and slow slip event

(1)为了实时监测日本西南部发生的低频地震的活动，我们研制了一套地震自动监测系统ATMOS。该系统使用分布在宽带网络上的实时地震数据，采用基于数值统计假设检验的方法，每隔两分钟分析一次是否发生地震。如果检测到震动，则确定其震源。该系统还创建显示监测结果的图像，并通过WWW自动向公众开放。(2)为了调查本戈海峡地区的低频地震活动，我们在广岛安装了宽带地震仪，该岛位于距离爱美县上和岛市约25公里的本戈海峡。安装的传感器为Streckeisen STS-2，数据记录器为QUATERRA Q330+PB14。地震数据是通过互联网使用ISDN电话线下载的。对地震图的分析表明，广岛台在2-20赫兹的震颤频带内的噪声水平低于九州岛靠近本戈海峡的地震台。广岛地震仪的安装使我们能够比以前更精确地观测本戈海峡地区的低频地震。

(1) To monitor activity of low-frequency tremors occur in southwest Japan in real-time, we have developed an automatic tremor monitoring system, ATMOS. The system uses real-time seismic data distributed on broadband network, and analyzes to examine whether tremor occur or not on every two minute by using a method based on a numerical statistical hypothesis test. If tremor is detected, then its hypocenter is determined. The system also creates images showing monitored results, and they are automatically opened to the public with WWW.(2) To investigate activity of low-frequency tremors in the Bungo channel region, we have installed a broadband seismometer at Hiburijima Island, which locates in the Bungo channel about 25 km away from Uwajima city, Ehime prefecture. The sensor installed is Streckeisen STS-2, and the data logger is QUATERRA Q330+PB14. Seismic data is downloaded by way of Internet using the ISDN telephone line. Analyses of seismograms have shown that the noise level at the Hiburijima station in the tremor frequency band between 2 and 20 Hz is lower than those at seismic stations in Kyushu Island near the Bungo channel. The installation of seismometer in Hiburijima island has allowed us to observe low-frequency tremors in Bungo channel region more precise than before.