Amphibious Monitoring of Earthquake Cycle Deformation at Subduction Zones Kelin Wang, Earl Davis, Herb Dragert Pacific Geoscience Centre, Geological Survey of Canada
We’ve come a long way in monitoring and modeling earthquake deformation 1973 (Bott and Dean) Today 1984 (Thatcher and Rundle) GPS satellites
GPS sites after the M 9. 0 Tohoku earthquake GSI website (Feb 26, 2012) North component Japa n Tre nch East component Vertical component
Japan and Sumatra: shortly after a great earthquake All sites move seaward Japa n Tre nch GSI website (Jan 29, 2012) Grijalva et al (2009)
Alaska and Chile: ~ 40 years after a great earthquake: Opposing motion of coastal and inland sites M = 9. 2 1964 Freymueller et al. (2009) Wang et al. (2007) M = 9. 5 1960
Cascadia: ~ 300 years after a M ~ 9 earthquake: All sites move landward Wells and Simpson (2001)
Coast line Inter-seismic 2 (Cascadia) Inter-seismic 1 (Alaska, Chile) Post-seismic (Japan, Sumatra) Co-seismic Coast line
Lou Rc ki u Rupture ptng re Afterslip ET S Stress relaxation Viscoelastic Stress relaxation 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)
Hu and Wang submitted Central part of Sumatra mesh M K
GPS observations and viscoelastic earthquake cycle model 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 Wang, Hu, He, submitted
Coast line Inter-seismic 2 (Cascadia) ? Inter-seismic 1 (Alaska, Chile) ? Post-seismic (Japan, Sumatra) ? Co-seismic ? ? ? Coast line
Coast line Tohoku Rupture from Inversion of GPS Co-seismic ? Coast line
Coast line JCG website Coseismic (contours) and 1 -yr postseismic (color) slip of 2005 Nias-Simeulue earthquake GPS stations coseismic slip (2 m contours) Post-seismic ? Hsu et al. (2006) Coast line
Coast line GPSA off Peru (Gagnon et al. , 2005) Inter-seismic ? ? Updip segment not slipping. Locked or fully relaxed? Coast line
Coast line Inter-seismic Tilt and pressure, (Ma. Guire & Collins, Funded project) ? ? Moored Buoy/GPS, (Chadwell et al. Poster, this meeting) Coast line
Fluid pressure during an ETS episode Pressure decrease: Dilatation Site 1253 Incoming plate Coast line ? ? Pressure increase: Contraction Site 1255 Overriding prism Davis, Heeseman & Wang (2011) Tremor beneath Nicoya Peninsula (minutes of activity per day) Coast line
Fluid pressure during an ETS episode Coast line ? ? Davis, Heeseman & Wang (2011) Coast line
Very-low-frequency earthquakes in Nankai accretionary prism Coast line ? ? Coast line
Coast line Fluid pressure during a VLF episode ? Site 808 Acc. Prism Near-trench boreholes off Mutoto ? Site 1173 Incoming Plate VLF events Davis et al. (2006) Coast line
ODP Hole 1173 ACORK, Just Seaward of Nankai Trench
Volumetric strain (dashed: Dilatation, pressure decrease)
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?
Cascadia tsunami warning using land seafloor geodesy Vancouver Victoria Cherniawsky et al. , (2007)
Seafloor pressure during Tohoku-earthquake tsunami propagation (ERI, U Tokyo website)
NEPTUNE Canada pressure sensors for tsunami detection/warning
Tsunami warning using land GPS t ka oo N t ul a Vancouver F JDF Ridge ia ad zone sc Ca tion uc bd Su Victoria
Tsunami warning using land GPS t ka oo N t ul a Vancouver F JDF Ridge ia ad zone sc Ca tion uc bd Su Victoria
Tsunami warning using land GPS t ka oo N t ul a Vancouver F JDF Ridge ia ad zone sc Ca tion uc bd Su Victoria
Tsunami warning using land seafloor geodesy t ka oo N t ul a Vancouver F JDF Ridge ia ad zone sc Ca tion uc bd Su Victoria
Tsunami warning using land seafloor geodesy t ka oo N t ul a Vancouver F JDF Ridge ia ad zone sc Ca tion uc bd Su Victoria Mc. Guire and Collins, funded project
Cascadia since the 1700 earthquake 1702 1741 1778 2012 Nootka Sound England 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). First Nations people of Nootka Sound traded with Captain Cook who was sailing along west coast of North America. Scientists discuss seafloor geodesy at UNAVCO workshop.
Скачать презентацию Amphibious Monitoring of Earthquake Cycle Deformation at Subduction
4c20ba35fa214fcd19d254b9fc97ed22.ppt