Title :
The development and evaluation of sensors for long-term borehole monitoring system
Author :
Kimura, T. ; Araki, E. ; Takayama, H. ; Kitada, K. ; Namba, Y. ; Kinoshita, M. ; Kyo, M.
Author_Institution :
Inst. for Res. on Earth Evolution, Japan Agency for Marine-Earth Sci. & Technol. (JAMSTEC), Yokosuka, Japan
Abstract :
In Integrated Ocean Drilling Program (IODP), the Long Term Borehole Monitoring System (LTBMS) is planned to be installed to sea bottom boreholes in the Nankai Trough area. LTBMS sensors are very sensitive instruments for collecting broadband dynamics with wide dynamic range for understanding earthquake mechanism. However, in IODP Exp.319, it was apparent that the strong ocean current “Kuroshio” cause vortex induced vibration (VIV) that gives damage to sensors in installation scheme. Thus, the LTBMS sensors have to be not only high sensitive but also rugged to survive against VIV. For this purpose, sensors with anti-vibration mechanism were developed by JAMSTEC project team. After development, noise evaluation test and vibration and shock tests that simulate vibration and shock in installation scheme were conducted for confirming the mechanism was working well. Furthermore, before and after the vibration and shock tests, power Spectral Density analysis was carried out using background noise recorded in low noise location, Matsushiro Seismological Observatory. As a result of this analysis, it was observed that the responses of sensors were not changed by the vibration and shock tests. Finally, all of these sensors were loaded to D/V Chikyu for installation to C0002 observatory in Exp.332.
Keywords :
earthquakes; oceanographic regions; oceanographic techniques; seafloor phenomena; seismology; seismometers; shock waves; vibrations; Integrated Ocean Drilling Program; JAMSTEC project team; Kuroshio ocean current; Long Term Borehole Monitoring System; Matsushiro Seismological Observatory; Nankai Trough area; antivibration mechanism; background noise; broadband dynamics; earthquake mechanism; low noise location; noise evaluation test; sea bottom borehole; sensor damage; sensor response; shock test; spectral density analysis; vibration test; vortex induced vibration; Accelerometers; Broadband communication; Electric shock; Noise; Sensors; Thermistors; Vibrations;
Conference_Titel :
Underwater Technology (UT), 2011 IEEE Symposium on and 2011 Workshop on Scientific Use of Submarine Cables and Related Technologies (SSC)
Conference_Location :
Tokyo
Print_ISBN :
978-1-4577-0165-8
DOI :
10.1109/UT.2011.5774128
