Submarine Cabled Real-time Seafloor Observatory and Subsea - - PowerPoint PPT Presentation

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Katsuyoshi KAWAGUCHI

Japan Agency for Marine-Earth Science and Technology

Submarine Cabled Real-time Seafloor Observatory and Subsea Engineering ROV for Observatory Construction

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Presenter Profile

Katsuyoshi Kawaguchi 1964: Bone in Tokyo 1993: Recived Ph.D in marine science from Tokai University 1993 to 1995: Lecturer, Tokai University 1995 to1996: Post-Doctoral Research staff, University of Hawaii 1996 to 1998: Post-Doctoral Researcher at JAMSTEC 1998 to 2008: Researcher at JAMSTEC 2008-:Principal Scientist / Group Leader Background: Underwater measurement Technology / Underwater Robotics Katsuyoshi KAWAGUCHI Principal Scientist / Group Leader Email: kawak@jamstec.go.jp Tel: (+81) 46-867-9342

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Submarine Cabled Real-time Seafloor Observatory and Subsea Engineering ROV for Observatory Construction

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A lot of earthquakes occurred every year around the Japan Arc, especially under the seafloor. The real-time and long-term monitoring capability on seafloor is essential for understanding and forecasting the earthquake activity and associated phenomenon along tectonic plate and submarine cabled seafloor

• bservation is only approach to be realize the requirements.

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DONET：

(Development of Ocean-floor Network System for Earthquakes and Tsunamis) is a national program to develop an ocean floor network system for earthquakes and tsunamis observation, and has been carried out since 2006.

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The Nankai Trough is one of the region with highest concern at present

• time. In this region, the Mega thrust earthquake and associated tsunami has
• ccurred every 100-150 years.

OSAKA YOKOHAMA

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• 250km length of backbone cable system
• 8 observatory interfaces for each hub system
• 20 interfaces are reserved for standard DONET observatory
• 5 hub system (Science Node)
• Another 20 interfaces are used for future expansion

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Replaceable, maintainable and expandable functions for future

• bservatory upgrade and replacement of superannuated system

components. REQUIREMENTS FOR EARTHQUAKES AND TSUNAMIS OBSERVATION High reliability system design to maintain constant (seamless) system

• peration in the system lifetime of 20years.

System Redundancy for the internal system failure or external failures associate with the earthquakes, Mud flows, human activities or abrasions. High density deployment of observatories (interval of 15-25km, same as seismic observation network on land) System Requirement Observation Requirement

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Operation Scenario of DONET Observatory Construction 20m 10km Extension Cable 20m Termination Unit Science Node Observatory

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Modification of ROV

Cable Laying System Variable Buoyancy Control System

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Variable Buoyancy Control System Science Node Installation: 500kg in Air / 180kg in SW Observatory Construction: 250kg in Air / 100kg in SW Extension Cable Laying : 640kg in Air / 220kg in SW Cable Management (Laying and Recovery) Suspend or Resume the Operation (release cable bobbin) Lay on Complex Seafloor Terrain Cable Laying System (Performances Required) Requirement for Modification

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Outer Diameter：< 6.5mm, Conductor Resistance:17Ω/km (Twist 4 copper threads for one conductor) Weight in Air：< 50kg/km, Weight in Water：<19kg/km (measured value = 18kg/km in seawater) Breaking Strength：≧100kgf

Cross Section and Specification of Extension Cable

• Extension cable secure the point to point

power distribution and communication channel

Extension Cable

• The observatory install 10km radius area

center the hub system

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The cable payout system can control the cable payout speed to manage the reasonable cable slack by hydraulic actuator. The slip roller mechanically managed the cable payout tension 30kg maximum. The slip roller set on the hinge mechanism that limit is 60deg lock to lock to follow the cable movement on the bobbin.

Cable Laying System

Cable Payout System

(Cable Management (Laying))

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(Suspend or Resume the operation)

Cable Laying System

Cable payout system has Clamp Mechanism to Remove/set extension cable from /to slip roller

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(Suspend or Resume the operation)

Cable Laying System

The cable bobbin elevator make possible to equip and release the cable bobbin together with 10km length of extension cable in air and water. It is generate 1ton of pulling torque that is good enough to lift the cable bobbin of 650kgf in air. The cable bobbin is fixed to the chasse of cable laying system with the pair of stab rod when operating.

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Add on Equipment :VBCS (Variable Buoyancy Control System)

Ballast Tank Filter Pump Servo Valve Control Monitor VBCS

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Consideration of Buoyancy

• Total ROV System Weight with 10km extension cable: 5.9 ton in air / neutral in seawater

90 220

• Bobbin: 40kg in seawater
• Extension cable: 18kg/km in seawater

120 70

• 50

VBCS

Touch Down Release Bobbin During Laying Operation Buoyancy Variation with VBCS Adjust Initial Condition

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SYSTEM ASSEMBLY TEST

Backbone Cable Repeaters Termination Unit Test Facility Branching Unit Observatory Extension Cable Science Node

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Backbone cable Laying Operation

TUs BUs Repeaters Cable Landing Operation: Jan 15, 2010 LWS Cables in Cable Tank Armored Cable Loading Lading to Cable Ship

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Science Node Installation

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Observatory Construction

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Extension Cable Laying Operation

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2010/3/13 21:46 Off Fukushima 37.6N 141.5E 80km M5.7 2010/3/13 21:46 Off Fukushima 37.6N 141.5E 80km M5.7 Pressure Gauge Differential Pressure Gauge Hydrophone Accelerometer Horizontal-1 Accelerometer Horizontal-2 Accelerometer Vertical BBS Horizontal-1 BBS Horizontal-2 BBS Vertical DONET A3a Observatory 33-38.905’N 136-36.220’E 2063m DONET A3a Observatory 33-38.905’N 136-36.220’E 2063m 21:47 JST 10Hz LPF 210 Pa 107 Pa 1.6 mm/s2 0.2 mm/s

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Conclusions

• The DONET is a development program for novel surveillance

infrastructure for earthquakes and tsunamis. This is four years program from April 2006 to March 2010. A new observation architecture development, sensing system development, field survey and related technologies development for seafloor observatory construction were discussed and demonstrated in this duration.

• The final stage of this program, the construction of network was

started January 2010, and successfully launched the first observatory in March 2010. This observatory produce very precise data set that has the quality has never had before

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Conclusions

• In addition, at this moment in time, 19 observatories are waiting in the

backyard to deploy on the seafloor near future. These apparatuses are scheduled to be installed to the seafloor and connected to the backbone cable system shortly in the expedition schedule after current year.

• The final destination of DONET will be deploy similar or more large

scale seafloor earthquakes surveillance system to the other major mega-thrust seismogenic zone around Japan and also the world.

2010

Pacifico Convention Plaza Yokohama & InterContinental The Grand Yokohama 11 ~ 14 May 2010 www.suboptic.org

enabling the next generation of networks & services

The 7th International Conference & Convention

• n Undersea Telecommunications

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