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)

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?

?

?

?

?

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

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?

Coast line

Coast line

?

Fluid pressure during a VLF episode

VLF events

Near-trench boreholes off Mutoto

Davis et al. (2006)

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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