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Amphibious Monitoring of Earthquake Cycle Deformation at Subduction Zones Kelin Wang, Earl Davis, Herb Dragert Pacific Geoscience Centre, Geological Survey.

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Presentation on theme: "Amphibious Monitoring of Earthquake Cycle Deformation at Subduction Zones Kelin Wang, Earl Davis, Herb Dragert Pacific Geoscience Centre, Geological Survey."— Presentation transcript:

1 Amphibious Monitoring of Earthquake Cycle Deformation at Subduction Zones Kelin Wang, Earl Davis, Herb Dragert Pacific Geoscience Centre, Geological Survey of Canada

2 1973 (Bott and Dean) 1984 (Thatcher and Rundle) Today We’ve come a long way in monitoring and modeling earthquake deformation GPS satellites

3 East component North component Vertical component GSI website (Feb 26, 2012) GPS sites after the M 9.0 Tohoku earthquake Japan Trench

4 GSI website (Jan 29, 2012) Japan and Sumatra: shortly after a great earthquake All sites move seaward Grijalva et al (2009) Japan Trench

5 Alaska and Chile: ~ 40 years after a great earthquake: Opposing motion of coastal and inland sites M = Freymueller et al. (2009) M = Wang et al. (2007)

6 Cascadia: ~ 300 years after a M ~ 9 earthquake: Wells and Simpson (2001) All sites move landward

7 Inter-seismic 2 (Cascadia) Inter-seismic 1 (Alaska, Chile) Co-seismic Coast line Post-seismic (Japan, Sumatra)

8 Rupture Viscoelastic Stress relaxation Stress relaxation Afterslip Locking ETS Rupture Characteristic timescales: Afterslip – months to a few years Viscoelastic relaxation (transient) – a few years Viccoelastic relaxation (steady-state) – several decades Locking – length of the earthquake cycle ETS type transients – whatever it takes (weeks to years)

9 Central part of Sumatra mesh MM KK   Hu and Wang submitted

10 A couple of years after 2004 M=9.2 earthquake (also NE Japan) Four decades after 1960 M=9.5 earthquake (also Alaska) Three centuries after 1700 M~9 earthquake GPS observations and viscoelastic earthquake cycle model Wang, Hu, He, submitted

11 Inter-seismic 2 (Cascadia) Inter-seismic 1 (Alaska, Chile) Co-seismic Coast line Post-seismic (Japan, Sumatra) ? ? ? ? ? ?

12 Co-seismic Coast line ? Tohoku Rupture from Inversion of GPS

13 Post-seismic Coast line ? coseismic slip (2 m contours) Hsu et al. (2006) GPS stations Coseismic (contours) and 1-yr postseismic (color) slip of 2005 Nias-Simeulue earthquake JCG website

14 Inter-seismic Coast line ? ? GPSA off Peru (Gagnon et al., 2005) Updip segment not slipping. Locked or fully relaxed?

15 Inter-seismic Coast line ? ? Moored Buoy/GPS, (Chadwell et al. Poster, this meeting) Tilt and pressure, (MaGuire & Collins, Funded project)

16 Coast line ? ? Fluid pressure during an ETS episode Davis, Heeseman & Wang (2011) Pressure decrease: Dilatation Pressure increase: Contraction Site 1253 Incoming plate Site 1255 Overriding prism Tremor beneath Nicoya Peninsula (minutes of activity per day)

17 Coast line ? ? Fluid pressure during an ETS episode Davis, Heeseman & Wang (2011)

18 Coast line Very-low-frequency earthquakes in Nankai accretionary prism ? ?

19 Coast line ? Fluid pressure during a VLF episode VLF events Near-trench boreholes off Mutoto Davis et al. (2006) ? Site 808 Acc. Prism Site 1173 Incoming Plate

20 ODP Hole 1173 ACORK, Just Seaward of Nankai Trench

21 Volumetric strain (dashed: Dilatation, pressure decrease)

22 Scientific targets for amphibious monitoring 1.Coseismic behaviour of the shallow, tsunamigenic part of the subduction fault. Strengthening or weakening? Slip gradient? 2.Postseismic motion of the shallow subduction fault. Is afterslip common? Does the rupture zone itself exhibit afterslip? Coseismic stress drop or increase? 3.Interseismic motion of the megathrust. 4.Strain transients during the interseismic period. Nature of “partial locking”? Modes of creeping? Connection with deep slow slip? 5.Interseismic deformation of incoming plate. 6.Rheology of the oceanic mantle in earthquake-cycle deformation. More viscous than mantle wedge in steady state? Similar transient behaviour to mantle wedge?

23 Cascadia tsunami warning using land and seafloor geodesy Victoria Vancouver Cherniawsky et al., (2007)

24 Seafloor pressure during Tohoku-earthquake tsunami propagation (ERI, U Tokyo website)

25 NEPTUNE Canada pressure sensors for tsunami detection/warning

26 Cascadia Subduction zone Nootka Fault JDF Ridge Vancouver Victoria Tsunami warning using land GPS

27 Cascadia Subduction zone Nootka Fault JDF Ridge Vancouver Victoria Tsunami warning using land GPS

28 Cascadia Subduction zone Nootka Fault JDF Ridge Vancouver Victoria Tsunami warning using land GPS

29 Cascadia Subduction zone Nootka Fault JDF Ridge Vancouver Victoria Tsunami warning using land and seafloor geodesy

30 Cascadia Subduction zone Nootka Fault JDF Ridge Vancouver Victoria Tsunami warning using land and seafloor geodesy McGuire and Collins, funded project

31 Cascadia since the 1700 earthquake England and France began to fight in eastern North America (Queen Anne’s War). First Europeans (Chirikov of Russia) landed on northwest coast of North America (Prince of Wales Island). Scientists discuss seafloor geodesy at UNAVCO workshop First Nations people of Nootka Sound traded with Captain Cook who was sailing along west coast of North America. Nootka Sound

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