Real time Monitoring System for Earthquakes and Tsunamis (DONET)

Transcription

1 Real time Monitoring System for Earthquakes and Tsunamis (DONET) NankaiTrough Yoshiyuki Kaneda Japan Agency for Marine-Earth Science and Technology (JAMSTEC) Presentation 1

2 Earthquakes in the Nankai Trough Tokyo Osaka Nagoya Tokai Hyuga nada Nankai 5-6cm/y Tonankai 2-3cm/y 4-5cm/y DONET target area Seismogenic Zone Philippine Sea Plate M8+ class earthquakes occur every years. 2 2

3 The historical EQs. around the Nankai trough Complex recurrence patterns! 1707 CD(TONANKAI) + E(TOKAI) + AB(NANKAI) 1854 CD(TONANKAI) + E(TOKAI) 32hours AB(NANKAI) 1944 CD(TONANKAI) 2years AB(NANKAI) 1946 M8 class EQs. are occurring with the interval of years 3

4 Simulation of Earthquake Occurrence in the Nankai Trough Relative velocity along to the plate boundary Earthquake Nankai Tonankai Tokai Coupled (Non Earthquake) 4

5 Simulation of Earthquake Occurrence in the Nankai Trough Variations of recurrence patterns are simulated qualitatively. First ruptures are starting from the Tonankai seismogenic zone. These results are consistent with past two earthquakes 1944/1946 and1854 EQs. The Tonankai seismogenic zone is very important field to understand the recurrence system of mega thrust earthquakes around the Nankai trough. 5

6 Dense Ocean floor Network System for Earthquakes and Tsunamis DONET Real time monitoring system for Seismogenic zone 6

7 Concept of DONET Osaka Tokyo Number of Science Node : 5 Nodes Number of User Interface : 8 ports / Node Power Distribution : 30 W / Port Data Transmission : 50 Mbit / s / Port Precise Timing Control : < 1μsec 7

8 Ground Motion Sensing System Observation Target : Broad Band Phenomena Long period seismic wave: Hz; m/s 2 - (at 0.05Hz) Micro earthquake: Hz; m/s 2 (at10hz) Large earthquake: Hz; m/s 2 (at 10Hz) Strong motion accelerometer Gimbals Mechanism Broadband seismometer

9 Pressure Sensing System and Peripherals Observation Target : Broad Band Phenomena Crustal Deformation: 1day sec; >1 Pa Tsunami: sec; >1 Pa Long period seismic wave: Hz; >1 Pa Micro earthquake: Hz; >1 Pa Large earthquake: Hz; >3MPa differential pressure gauge quartz pressure gauge hydrophone precision thermometer for sensor calibration

10 Dense network array Concept of DONET Multi kinds of seismometers and pressure sensors Redundancy: Equipping redundant configuration on backbone cable and node Expandability: Branching unit enables wide-spread distribution of observation points. Node plays the role of hub that connects underwater instruments to the backbone cable system. Replaceable function: Replacing observation unit at the seafloor by using underwater removable connector Maintainability: Operation on the seafloor by using Remotely Operated Vehicle (ROV) 10

11 Data transfer system (DONET)

12 Landing Station Node Branching Unit 1900m Backbone Cable 4300m Ground Motion Sensing System Pressure Sensing System and Peripherals Extension Cable Remotely operated vehicle 12

13 Installation of Science Node Japanese research ROV Hyper Dolphin Installed Termination Equipment N, E,Depth:2009m Construction of Installation hole for seismometer Port Installation hole Installation of sensors N, E Installed Science Node(A010) N, E,Depth:2009m

14 Movie of DONET deployment 14

15 Installation of DONET(2011 Jan.) 8 Observatories are working 5 Nodes are deployed Construction of Installation hole for seismometer Installation of seismometer Deployment of extension cable Installation of sensors

16 Choosing appropriate sensors for target phenomena DONET sensor chooses seismometers and pressure gauges suitable to observe very small to large earthquakes, Tsunamis, and slow ground deformation. We need set of sensors of very broad frequency range and wide dynamic range. Tsunamis Slow ground deformation Long period Seismic waves Earthquakes Slow ground deformation Long period Seismic waves Earthquakes

17 Earthquake early warning 4sec 2sec 4sec 2sec 4sec 2sec The red parts show the DONET detects earthquakes earlier than land stations. 17

18 Tsunami early warning 0.1=6min 0.1=6min 0.2=12min 0.2=12min The red parts show the DONET detects tsunamis earlier than land stations. 18

19 2010/08/13 21:19 (UTC) Mariana (M=6.9) Location:12.5N, 141.5E Depth:10km (USGS) Broadband seismometer DONET Strong motion accelero meter Seismic wave Pressure gauge Observed Tsunami sec Pressure gauge 19

20 2010/10/16 16:59(JST) Kumano-nada (M=2.3) DONET data (Sea bottom) NanTro SEIZE area :Earthquake Epicenter Location:33.3N, 136.9E Depth:47.3km (JMA) The seismic signals recorded by the DONET installed in the Kumano-nada reached 5 to 10 seconds earlier than land stations. 10sec Hi-NET data (Land station) 20

21 Tsunami observation by the ocean-bottom pressure gauges of DONET: An earthquake off Marianas on 13, August, 2010 JMA OWASE DONET KMA03 21:19 August 13, 2010 (UTC) Epicenter : off Marianas Depth :12 km Mw : 6.9 Position of DONET observation point and JMA Normal fault with some strike slip compornent 21

22 Comparison of the observed tsunami between the offshore and costal stations DONET KMA03 JMA OWASE Original seismic wave 1 cm Tsunami 10 cm Tsunami Band-pass filtered ( sec) noise level 0.5 cm noise level 5 cm Earthquake occurrence time DONET Data The tsunami signal is very clear in comparison with the background noise. The seismic wave is also recorded at the data. Non-linearity of tsunami propagation could not be required because of open sea observations 22

23 DONET 2 23

24 DONET 2 Concept A similar seafloor network system (DONET2) is needed for region off Kii Peninsula and Shikoku to decrease disasters caused by the seduction zone earthquakes in the Nankai Trough. Achievement of early detection of earthquake and tsunami in a wider area Advancement of earthquake occurrence simulation Development of Most Advanced and Leading Technologies DONET2 24

25 DONET2 High Voltage System After DONET completion, move on to DONET2 with High Voltage System, then observational area expand to the Nankai seismogenic zone Middle voltage system 3000V High voltage system 10KV Cable length 300km + DONET type NODE 5 (40 ocean floor sites) Cable length1000km + DONET type NODE over 10 (100 ocean floor sites) DONET1 DONET2 25

26 Improvement of Simulation Models -Data assimilation- Observation data Predict 2 Predict (n) Optimization Time range for data assimilation Long term predict using predict (n) time Improvement Simulation model Without improvement Improvement time 26

27 Expected slip velocity on the plate interface before the Tonankai earthquake Fast (rupture) Slip acceleration before Tonankai earthquake Red:DONET1 Blue and Green:DONET2 Slow (locked) 27

28 Expected seafloor crustal deformation before the Tonankai earthquake Slip acceleration before Tonankai earthquake DONET1(Node E) Vertical displacement Tonankai Earthquake Subsidence Uplift 1cm Years before Tonankai Earthquake 28

29 Expected slip velocity on the plate interface after the Tonankai earthquake Fast (rupture) After slip of Tonankai earthquake propagates westward and triggers nucleation of Nankai earthquake starts Slow (locked) 29

30 Expected seafloor crustal deformation after the Tonankai earthquake Simulation of Nankai earthquake After slip of Tonankai earthquake Slip acceleration following after slip Tonankai Vertical displacement Nankai Tonankai Vertical displacement Subsidence Uplift Nankai Days after Tonankai earthquake Days after Tonankai earthquake Days after Tonankai earthquake Vertical displacement Tonankai Nankai 30 30

31 DONET, DONET2, and DONET3 Tokyo Osaka Nagoya DONET DONET2 DONET3 Extended Part 31

32 Collaboration and Integration Further, we have to develop more network systems ESONET DONET: JAPAN MACHO: TAIWAN Korea:? NEPTUNE CANADA/US Seoul Tokyo INDIAN OCEAN SOUTH AMERICA Map: Wikipedia The international collaboration is very important 32

33 Connection of NantroSEIZE borehole observatories These observatories will be connected to DONET to assure long-term monitoring. Riser ~ 2.5km hole Riser less ~ 1km hole below sediment layer. Riser less ~ 500m hole penetrating shallow splay fault Location of the borehole observatories are planned within the reach (10km or 20km) of DONET. Connection of the borehole observatories will be funded as a part of JAMSTEC s borehole observatory project (not by DONET). 33

34 Appearance of Installation of Long-term borehole measuring device broadband seismometer m depth Seafloor surface hole entrance device Screen (The hole to measure for Stratum Temperature/pressure ) thermometer Sensor career (clinometer, seismometer) Packer (Blockage of inside of casing) Casing (about 24.4cm in diameter) 888m Strain indicator (Depth of casing) Head_Landing_5times.avi on desktop cement [photo] descent to moat grinding borehole of the appearance of installation of long-term The photograph of appearance of work for seafloor at an unmanned probe on Dec. 8th, 2011 Video (five times faster) Head_Landing_5times.avi on desktop 34 seawater 987m (moat grinding depth) Reference : CDEX/JAMSTEC

35 Advanced estimation of the earthquake and Tsunami Evaluate of Seismic Linkage around the Nankai trough Ocean floor network system Seismogenic zone drilling Simulation Precise survey DONET CHIKYU Super Computer R/V KAIREI Prevention and mitigation It s important to collaborate with many countries 35

36 Thank you for your attention 36