Compact Seafloor Cabled Seismic and Tsunami Observation System Enhanced by

Information and Communication Technology

Masanao SHINOHARA1, Tomoaki YAMADA1, Shin’ichi SAKAI1, Hajime Shiobara1, and Toshihiko KANAZAWA2

1 Earthquake Research Institute, the University of Tokyo 2 National Research Institute for Earth Science and Disaster Prevention

CTBTO Science and Technology Conference 2015 T3.1 Design of Sensor Systems

KLEINER REDOUTENSAAL 14:15-14:30 June 23, 2015

Seafloor seismic tsunami observation system using optical cable off Sanriku, Japan

TM2 TM1

2 Fujii et al., 2011

n  3 seismometers and 2 tsunami gauges n  Installed in 1996 n  Total length is 120km n  Data transmission: tele-communication

technology (ITU-T G.704) n  The data contributes to estimate source

region of the tsunami n  The landing station was rebuilt

Time

OBS3 OBS2 OBS1

TM2 TM1

[m]

Seismometer + Tsunami-meter

Concept of new OBCST - larger coverage, higher density, more flexible -

n  Inline system for cost and rapid deployment n  Downsizing and technology for wide use with high reliability n  Software based system for flexibility of system

3

Seismometer + external port S-NET

n  Coverage of wide area n  Spatial higher density n  expandable, maintenance

DONET

n  Backbone cable uses traditional technology

n  Extension by external port n  Expansion of cable by ROV

n  Traditional system with high reliability

n  Large coverage by inline system

New system

n  Lower cost for total system n  Large number of observation node n  external port and flexibility

ICT and up-to-date electronics

4

First generation OBCS system in the Japan Sea

Landing station

Cabled Seismometer (CS)

Installed on Aug. 2010 Power supply Master clock Data recording

Cabled seismometer　4 Interval 5 km, Landing 1

Internal unit of CS

The system is buried 1 m below seafloor at depth greater than 20 m

Data are sent to ERI

n  ICT is used. Low-cost and high-reliability n  Down-sizing and low-power consumption of CS

by up-to-date electronics (e.g. FPGA)

Continuous recording for 5 years

The second cabled system off Sanriku

5

n  IP system (Second generation of our system) 　　Low-cost, high reliability system using TCP/IP and in-line system

n  3-C seismometer and pressure gauge/PoE port for a node n  3 nodes, total length is 105 km n  Landing station for existing system is available

Existing cable

Specifications Max depth:6,000 m Data transfer speed:1Gbps (IEEE802.3ｚ) Timing accuracy:0.1 ms 1 landing Supply voltage:250 V, current 0.8 A Sensors:JA-5 type III, 8B7000-2

6

Network configuration for new Sanriku OBCST

Duplicate for clock line Improvement of reliability and cost performance

Route turn

PoE Interface TCP/IP I/F,　10Mbps:Supplying power 12W Connection of broadband seismometer, pressure gauge, etc.

7

System development for new Sanriku OBCST Sensors for observation l  3-C accelerometer

(equipped on all nodes) l  Precise pressure

gauges(Buried nodes) l  External sensor via PoE

port (various type sensor)

Based on the first system n  Microprocessor control n  Integration with FPGA

•  GigaBit Ethernet Increase amount of data •  WDM Decrease of fiber number •  IEEE1588 Precise timing through Ethernet •  Atomic clock Stand-alone precise timing

n  Pressure gauge 　 Tsunami, crustal movement n  PoE port by UMC Replace of sensor by ROV

SFP

SFP

SFP

SFP

SFP

SFP

FPGA

Atomic Clock

A/D I/F

PLL PLL

CPU

RAM

RAM RAM

ROM

ADC

I/F

Power Reg.

Layout of electronics unit for new Sanriku OBCST

8

9

Performance of system

Pressure gauge

Electronics unit including seismometers

JAE JA-5TypeIII Paroscientific 8B7000-2-005

Optical fiber

Node0

Node1

To evaluate a performance of electronics unit, seismic observations by using proto-type was performed in April, 2013

Clock on land

400ns

Clock on a node

Installed at a vault with depth of 100 m in Nokogiri-yama geophysical observatory, ERI

Time synchronization with accuracy of 300 ns through Ethernet

10

Practical system

Pressure gauge

Electronics unit including seismometers

Fiber

Node0

Node2(PoE)

Power

Landing system

Records of pressure gauge

2014-04-09 00:02 Off Ibaraki　 Depth=58km M 4.6 D~200km

n  Electronics units are improved from the results of evaluation of proto-type.

n  PoE is implemented

Node2 (4-8Hz)

Electronics units for deployment are under evaluation from April 2014

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External devices through PoE

Electronics unit has PoE function

n  TCP/IP interface（10Mbps) n  Power of about 12W can be supplied. n  After deployment system, additional sensor

can be attached by using UMC n  Cable system functions for ethernet line.

Example (pressure gauge) n For a test, p. gauge with digital output is connected.

n P. gauge seems to connect a server directly on landing

Pressure canister for new Sanriku OBCST

12

Pressure gauge Electronics unit

c.a. 1300

c.a. 4800 c.a.1300 Φ265

Pressure canister for observation node　　　　　　　 •  Use of existing canister •  Optimal heat-radiation •  Enclosing by welding •  Feed-through •  Mount of pressure gauge or UMC

UMC (PoE port)

Electronics unit

Pressure gauge

Production and installation

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October, 2014 n  Completion of production of three

observation node. March, 2015 n  The observation nodes were connected

with seafloor optical fiber cable September, 2015 (Plan) n  System deployment

Seafloor survey for cable route had been carried out in August, 2013.

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Cabled seismometers

15

Summary n  Compact OBCS using ICT has been developed for monitoring of

seismic activities and tsunami.

n  First installation of the ICT system was performed in the Japan Sea in 2010.

n  The observation continues for 5 years.

n  Sanriku system deployed in 1996 caught the 2011 huge tsunami 15-20 minutes before it reached the coastline.

n  A second ICT system based on the first ICT system is installing in this September close to the 1996 system.

n  Each node has a seismometer. Two nodes equips with a pressure gauge, and the other has a PoE external port.

n  The system has 1Gbps Ethernet, and IEEE1588 for timing. n  The system is ready.