Advanced ocean floor observatory for mega-thrust earthquakes and tsunamis around the Nankai Trough, Southwestern Japan Yoshiyuki KANEDA DONET GROUP Department.

Advanced ocean floor observatory for mega-thrust

earthquakes and tsunamis around the

Nankai Trough, Southwestern Japan

Yoshiyuki KANEDA DONET GROUP

Department of Oceanfloor Network System Development for Earthquakes and Tsunamis

DONETJapan Agency for Marine-Earth Science ant Technology

JAMSTEC

Previous research in the Nankai trough

NANKAI TROUGH

KII peninsula

year age A B C

1605 KEICHO

1707 HOUEI

1854 ANSEI

1944 SYOWA

1946 SYOWA

Historical EQs. in the Nankai trough

A;Nankai EQ.B;Tonankai EQ.C;Tokai EQ.

？

PSP

Tonankai TokaiNankai

111 years

7days

103 years

97days

①①

②②

③③

103years

97days

TonankaiNankai③③

111 years7days

Tonankai ＋ Tokai Nankai②②Tonankai ＋Nankai

①①

The results of mega-thrust EQ. recurrencecycle simulation in the Nankai trough

Advanced Ocean Floor Cable System

Outline & Concept

Image

Ocean floor cable network system as MEXT project

Sensors

・　 over20 Seismometers・　 20 Pressure gauges

海底ネットワークシステムコンセプト

Backbone cable system

Brunch unit

Sensor system

Extendable Advanced Sensor System

Replaceable Observatory Node

High Reliability Backbone Cable System

Landing Station

Seismometers,Pressure gauge

Outline of ocean floor cable system

・ Speedy evaluation and notification for earthquakes and tsunamis.

・ Provide observed data such as ocean floor deformation derived from pressure gauges to improve the simulation and modeling researches about the mega- thrust earthquakes. (Data assimilation)・ Understanding of the interaction between the crust and upper mantle around subduction zone.

Data Application

Maintenance systems of JAMSTEC３０００ｍ Class ROV 「 HYPER-DOLPHIN 」

７０００ｍ class deep sea ROV「 KAIKO7000 」

Deep Sea Cruising AUV 「 URASHIMA 」

Network Array Planning

Advanced Ocean Floor Cable System

Network array planning

Kii PeninsulaTonankai Seisomogenic Zone

Nankai Seisomogenic Zone

sensor

node

Back bonecable

Advanced Ocean Floor Cable System

Image

海域でおこる地震活動の検知The resolution test of hypocenter

determination using oceanfloor network

Network Array Good resolution!!

▲： Land GPS and Pressure gauge

Resolution

　・ Land GPS ：horizontal; 1mmvertical; 　 3mm

・ Pressure gauges: 10mm

Ocean network system(36 pressure gauges)+ Land GPS

The checker board test for offshore geodetic data analyses

Land GPSModel

40 ｋｍ square checker boardSlip rate : ±1m

Good resolution!!Around network array

Advanced Ocean Floor Cable System

Sensors １） Multi seismometers for ・ Broad band phenomena ・ Strong Motion ・ Micro EQs.２） Precise pressure gauges for ・ Tsunami ・ Ocean floor deformation３） Data s ｔ o ｒａｇｅ function at the trouble

Under development＊ Precise ocean floor deformation monitoring system＊ Advanced in lined sensor cable system

Provide the estimated results before arriving seismic wave in populated area

Observe seismic wave by network

・ Magnitude・ Focal mechanism・ Asperity area

Synthetic waveform

Research on real time estimation Research on real time estimation of source elements using network of source elements using network data (regional analysis)data (regional analysis)

K-net

Ocean floor network

Tonankai Eq.

Analyze with theoretical data

Database

①

②

③

Gather data

④⑤

Construct source model and pre-estimate Tsunami waveform

Analyze③

Structure model by JAMSTEC

Improve simulation model

　　　　 Data assimilation ：　　　　 using pressure gauge data as

ocean floor deformation monitoring

Keyword: Long term observatory

Improve the simulation model

Observation data

Data assimilation

Predict 2

Predict (n)

Time range for data assimilation

Optimization

time

Long-term predictusing predict (n)

time

Without improvement

Improvement

Improvement Simulation model

Network data flow

Network

Land Station

JAMSTECData center

JMAOthers

analyses

analyses

Advanced Ocean Floor Cable System

Image

Ocean floor cable network system as MEXT project

Sensors

・　 over20 Seismometers・　 20 Pressure gauges

Project・　 FY2006-FY2009 4 years

System Concept

・ Redundancy, Extension and advanced maintenance system using the looped cable system, junction boxes and the ROV/AUV etc.

・ Speedy evaluation and notification for earthquakes and tsunamis.

・ Provide observed data such as ocean floor deformation derived from pressure gauges to improve the simulation and modeling researches about the mega-thrust earthquakes.

・ Understanding of the interaction between the crust and upper mantle around subduction zone.

Data Application

Keywords: Landing both cable end, Node, Brunch unit

Nicoya

Osa

Future Plan??

Ocean floor cable network system