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Amphibious Monitoring of Earthquake Cycle Amphibious Monitoring of Earthquake Cycle
Deformation at Subduction Zones Deformation at Subduction Zones
Kelin Wang, Earl Davis, Herb DragertKelin Wang, Earl Davis, Herb DragertPacific Geoscience Centre, Geological Survey of CanadaPacific Geoscience Centre, Geological Survey of Canada
1973 (Bott and Dean)
1984 (Thatcher and Rundle)
Today
We’ve come a long way in monitoring and modeling earthquake deformation
GPSsatellites
East componentEast component
North componentNorth component
Vertical componentVertical component
GSI website(Feb 26, 2012)
GPS sites after the M 9.0 Tohoku earthquake
Japa
n T
renc
h
GSI website(Jan 29, 2012)
Japan and Sumatra: shortly after a great earthquakeAll sites move seaward
Grijalva et al (2009)
Japa
n T
renc
h
Alaska and Chile: ~ 40 years after a great earthquake:Opposing motion of coastal and inland sites
M = 9.2 M = 9.2 19641964
Freymueller et al. (2009)
M = 9.5 M = 9.5 19601960
Wang et al. (2007)
Cascadia: ~ 300 years after a M ~ 9 earthquake:
Wells and Simpson (2001)
All sites move landward
Inter-seismic 2 (Cascadia)
Inter-seismic 1(Alaska, Chile)
Co-seismic
Coast line
Coast line
Post-seismic(Japan, Sumatra)
Rupture
ViscoelasticStress relaxation
Stress relaxation
Afterslip
LockingETS
Rupture
Characteristic timescales:Afterslip – months to a few yearsViscoelastic relaxation (transient) – a few yearsViccoelastic relaxation (steady-state) – several decadesLocking – length of the earthquake cycleETS type transients – whatever it takes (weeks to years)
Central part of Sumatra mesh
M
K
Hu and Wangsubmitted
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
Inter-seismic 2 (Cascadia)
Inter-seismic 1(Alaska, Chile)
Co-seismic
Coast line
Coast line
Post-seismic(Japan, Sumatra)
?
?
?
?
?
?
Co-seismic
Coast line
Coast line
?
Tohoku Rupture from Inversion of GPS
Post-seismic
Coast line
Coast line
?coseismicslip (2 m contours)
Hsu et al. (2006)
GPS stations
Coseismic (contours) and 1-yr postseismic (color) slip of 2005 Nias-Simeulue earthquake
JCG website
Inter-seismic
Coast line
Coast line
?
?
GPSA off Peru (Gagnon et al., 2005)
Updip segment not slipping. Locked or fully relaxed?
Inter-seismic
Coast line
Coast line
?
?
Moored Buoy/GPS,(Chadwell et al.
Poster, this meeting)
Tilt and pressure,(MaGuire & Collins,
Funded project)
Coast line
Coast line
?
?
Fluid pressure during an ETS episode
Davis, Heeseman& Wang (2011)
Pressure decrease:Dilatation
Pressure increase:Contraction
Site 1253Incoming plate
Site 1255Overriding prism
Tremor beneathNicoya Peninsula
(minutes of activity per day)
Coast line
Coast line
?
?
Fluid pressure during an ETS episode
Davis, Heeseman& Wang (2011)
Coast line
Coast lineVery-low-frequency earthquakes in Nankai accretionary prism
?
?
Coast line
Coast line
?
Fluid pressure during a VLF episode
VLF events
Near-trench boreholes off Mutoto
Davis et al. (2006)
?
Site 808Acc. Prism
Site 1173Incoming Plate
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 and seafloor geodesy
VictoriaVictoria
VancouverVancouver
Cherniawsky et al., (2007)
Seafloor pressure during Tohoku-earthquake tsunami propagation
(ERI, U Tokyo website)
NEPTUNE Canada pressure sensors for tsunami detection/warning
Cascadia
Subduction zone
Nootka
Fau
ltJD
F R
idge
VancouverVancouver
VictoriaVictoria
Tsunami warning using land GPS
Cascadia
Subduction zone
Nootka
Fau
ltJD
F R
idge
VancouverVancouver
VictoriaVictoria
Tsunami warning using land GPS
Cascadia
Subduction zone
Nootka
Fau
ltJD
F R
idge
VancouverVancouver
VictoriaVictoria
Tsunami warning using land GPS
Cascadia
Subduction zone
Nootka
Fau
ltJD
F R
idge
VancouverVancouver
VictoriaVictoria
Tsunami warning using land and seafloor geodesy
Cascadia
Subduction zone
Nootka
Fau
ltJD
F R
idge
VancouverVancouver
VictoriaVictoria
Tsunami warning using land and seafloor geodesy
McGuire and Collins, funded project
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.
1702 1741 20121778
First Nations people of Nootka Sound traded with Captain Cook who was sailing along west coast of North America.
Nootka Sound