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We have developed an automated cable-laying system that is operated with a remotely operated vehicle (ROV) and can automatically dispense a thin optical-fiber submarine cable at a rate that keeps pace with the ROV's ground speed. The use of an ROV allows to install a thin optical-fiber submarine cable on the deep seafloor accurately and safely. The ROV-based automated cable-laying system is being...
NEC is participating in the development of the next-generation marine resource investigation technology “The development of the cable type observation system” which is one of the development items in the SIP project. Under the technical guidance of JAMSTEC, NEC developed DONET system which has NODE equipment. Special feature of NODE system is ocean bottom observation equipment mobility, expandability...
DONET (Dense Oceanfloor Network System for Earthquakes and Tsunamis) is a cabled observation system for long-term and real time monitoring using precision sensors on the seafloor. The development and the manufacturing of DONET2 system were commenced in 2013, and the construction was completed on schedule in 2016. In this paper, the DONET2 system and its installation technologies are introduced.
Real-time borehole observation system for seismogenic zone monitoring called long-term borehole monitoring system (LTBMS) was developed to give better access to the seismogenic faults nucleating earthquakes while avoiding observational effects of dampening by shallow soft sediment and oceanographic noise commonly experienced in the seafloor observation. Installation of the LTBMS has been conducted...
As part of the Next-Generation Technology for Ocean Resources Exploration project in the Cross-ministerial Strategic Innovation Promotion Program (SIP) of the Japanese government, Japan Agency for Marine-Earth Science and Technology (JAMSTEC) is promoting the development of the cabled seafloor observatory system which allows long-term monitoring of hydrothermal vents and ecological changes. Exploring...
Utilizing a variety of substances which exist in seafloor as resources has a possibility to influence on the environment. The practical use of seafloor resources needs a development of environmental impact prediction method and a development of framework to carry out the continuous environmental impact assessment. A submarine cabled observatory is plant to deploy to hydrothermal activity area in submarine...
We have installed the Dense Oceanfloor Network System for Earthquakes and Tsunamis (DONET) that includes 20 observatories at Kumanonada (called DONET1) for the purpose of monitoring the seismogenic zone around the Nankai Trough. During the construction of DONET1, a remotely operated vehicle (ROV) was successfully used to lay the optical-fiber submarine cables that connect the observatories with the...
The seismometer used in Dense Oceanfloor Network system for Earthquakes and Tsunamis (DONET), is buried under the seabed to suppress the background noise [1]. To make a hole for burying the seismometer, a new caisson installation technique using hydraulic vibration hammer is developed. This paper describes the detail of the hammer, a field test, and a trial test in deep sea.
DONET (Dense Ocean-floor Observatory Network for Earthquakes and Tsunamis) is a submarine cabled real-time seafloor surveillance infrastructure for earthquake activity at assumed focus region of mega-thrust earthquake around Japan. The original system DONET1 was constructed in To-Nankai earthquake focus region and twenty seafloor observatories are working in operation beginning in 2011 to contribute...
This paper describes a ROV-based automated cable-laying system that can automatically payout a thin optical-fiber submarine cable while keeping balance with the ground speed and adjusting the degree of cable tautness. This system has been developed to reduce the physical and mental burdens on the ROV operator(s) and to speed up the construction of DONET (Dense Oceanfloor Network System for Earthquakes...
Underwater repair method for insulator of the optical submarine cable has been developed and test samples were successfully repaired in deep-sea field tests.
This paper describes an automated cable-laying system that can automatically pay out a submarine cable on the seafloor while keeping balance with the ground speed. We have installed DONET (Dense Oceanfloor Network System for Earthquakes and Tsunamis) at Kumanonada and a ROV (Remotely Operated Vehicle) was successfully used to lay the cables which connect observatories to the nodes of the DONET. However,...
One of the observation target of the seafloor cabled observation network called Dense Ocean Network for Earthquake and Tsunamis (DONET) in the Nankai Trough, south of Japan, is slow and weak seismic motion. The target necessitated installation of broadband seismometers in the seafloor in a very quiet background noise environment. We developed a technique to install seismometer in a buried caisson...
Underwater repair method for insulator of the optical submarine cable has been developed and test samples were successfully repaired in deep-sea field tests. In this paper, the detail of the new repair method, equipment, trial test in a laboratory and the deep-sea field experiments are described.
Institute of Industrial Science, University of Tokyo (IIS) has launched a five-year long project to develop next-generation seafloor geodetic observation system in 2005. Principal idea of the observation system is to utilize AUV, seafloor platform and submarine cable in place of using a research vessel and a stand-alone type seafloor benchmark transponder. This observation system aims at promoting...
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