著者

川北 優子 酒井 慎一

出版者

東京大学

雑誌

東京大學地震研究所彙報 (ISSN:00408972)

巻号頁・発行日

vol.84, no.2, pp.127-139, 2010-01-28

---

The Special Project for Earthquake Disaster Mitigation in the Tokyo Metropolitan Area has been ongoing (2007−2012). Under this project, the Metropolitan Seismic Observation network (MeSO-net), which consists of about 400 observation sites, has been constructed. The correlations of waveform from local and teleseismic events are high because observation sites are deployed at about 2 or 3-km intervals. In addition, the later phase is easily identified although artificial noise is very intense. However, we are attempting to improve quality by characterizing the various types of noise. In the metropolitan area, various human activities are observed that generate noise such as trains, automobiles, aircrafts, factories, and electrical power. These adversely affect our observations. We recognize various types of noise from continuous records. A spectral graph and a spectrogram in each station are useful for characterizing signals and noise. We also discovered a form of system noise obtained from the relationship between sensor and electrical circuit. We named it Aurora Noise. The strength of Aurora Noise was reduced by improving the electrical circuit. Our study will lead to improving the quality of observed data, and contribute to a new assessment of seismic hazard in the Tokyo Metropolitan Area in Japan.

著者

中川 茂樹 鶴岡 弘 川北 優子 酒井 慎一 平田 直

出版者

東京大学地震研究所

雑誌

地震研究所彙報 (ISSN:00408972)

巻号頁・発行日

vol.84, no.2, pp.107-114, 2009

---

We launched the Special Project for Earthquake Disaster Mitigation in the Metropolitan Tokyo area to obtain high-resolution images of three-dimensional seismic wave velocity and attenuation structures. The core item of this project is a dense seismic array called MeSO-net for making observations in the metropolitan area. MeSO-net consists of 400 seismic stations, from which data are continuously collected at the Data Center at ERI. At the Sub-Center at NIED, data are backed up and integrated with Hi-net data. Seismic data with a sampling rate of 200 Hz are transmitted to the Data Center using ACT protocol. Data from all stations are received at the Data Center at ERI. After checking the quality (including lost packets) of data received, data are automatically processed and archived using the WIN system. This observational network and the Data Center are equipped with several new functions for reliable data transmission and ease of maintenance.

著者

川北 優子 酒井 慎一

出版者

東京大学地震研究所

雑誌

地震研究所彙報 (ISSN:00408972)

巻号頁・発行日

vol.84, no.2, pp.127-139, 2009

---

The Special Project for Earthquake Disaster Mitigation in the Tokyo Metropolitan Area has been ongoing (2007−2012). Under this project, the Metropolitan Seismic Observation network (MeSO-net), which consists of about 400 observation sites, has been constructed. The correlations of waveform from local and teleseismic events are high because observation sites are deployed at about 2 or 3-km intervals. In addition, the later phase is easily identified although artificial noise is very intense. However, we are attempting to improve quality by characterizing the various types of noise. In the metropolitan area, various human activities are observed that generate noise such as trains, automobiles, aircrafts, factories, and electrical power. These adversely affect our observations. We recognize various types of noise from continuous records. A spectral graph and a spectrogram in each station are useful for characterizing signals and noise. We also discovered a form of system noise obtained from the relationship between sensor and electrical circuit. We named it Aurora Noise. The strength of Aurora Noise was reduced by improving the electrical circuit. Our study will lead to improving the quality of observed data, and contribute to a new assessment of seismic hazard in the Tokyo Metropolitan Area in Japan.

著者

川北 優子 酒井 慎一

出版者

東京大学地震研究所

雑誌

地震研究所彙報 (ISSN:00408992)

巻号頁・発行日

vol.84, no.2, pp.127-139, 2009

---

The Special Project for Earthquake Disaster Mitigation in the Tokyo Metropolitan Area has been ongoing (2007−2012). Under this project, the Metropolitan Seismic Observation network (MeSO-net), which consists of about 400 observation sites, has been constructed. The correlations of waveform from local and teleseismic events are high because observation sites are deployed at about 2 or 3-km intervals. In addition, the later phase is easily identified although artificial noise is very intense. However, we are attempting to improve quality by characterizing the various types of noise. In the metropolitan area, various human activities are observed that generate noise such as trains, automobiles, aircrafts, factories, and electrical power. These adversely affect our observations. We recognize various types of noise from continuous records. A spectral graph and a spectrogram in each station are useful for characterizing signals and noise. We also discovered a form of system noise obtained from the relationship between sensor and electrical circuit. We named it Aurora Noise. The strength of Aurora Noise was reduced by improving the electrical circuit. Our study will lead to improving the quality of observed data, and contribute to a new assessment of seismic hazard in the Tokyo Metropolitan Area in Japan.

著者

中川 茂樹 鶴岡 弘 川北 優子 酒井 慎一 平田 直

出版者

東京大学地震研究所

雑誌

地震研究所彙報 (ISSN:00408992)

巻号頁・発行日

vol.84, no.2, pp.107-114, 2009

---

We launched the Special Project for Earthquake Disaster Mitigation in the Metropolitan Tokyo area to obtain high-resolution images of three-dimensional seismic wave velocity and attenuation structures. The core item of this project is a dense seismic array called MeSO-net for making observations in the metropolitan area. MeSO-net consists of 400 seismic stations, from which data are continuously collected at the Data Center at ERI. At the Sub-Center at NIED, data are backed up and integrated with Hi-net data. Seismic data with a sampling rate of 200 Hz are transmitted to the Data Center using ACT protocol. Data from all stations are received at the Data Center at ERI. After checking the quality (including lost packets) of data received, data are automatically processed and archived using the WIN system. This observational network and the Data Center are equipped with several new functions for reliable data transmission and ease of maintenance.