Water Tectonics and the Roots of Utah's Earthquakes
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Transcript of Water Tectonics and the Roots of Utah's Earthquakes
Water Tectonics andthe Roots of Utah’s
Earthquakes
Tony Lowry
Weather Forecasting:
TemperaturePressure
Water
Flow of Energy
& Matter
Seismic Forecasting?
Seismic Forecasting?
Seismic Forecasting?
Mw 6.9 Borah Peak earthquake
? ? ?
Seismic Forecasting?
Inte
rmou
ntai
nS
eism
ic B
elt
Crust(Feldspar,Quartz)
Mantle(Olivine,Pyroxene)
Cold (~0°C)
Hot (~1350°C)
Brittle Stre
ngth
Crustal Flow Strength
Mantle Flow Strength
Earthquakes here!
Active TA Seismic
Past TA Seismic
Permanent Seismic
Permanent GPS
Electrical (MT)
EarthScope
Higher H2O
Property Higher Temp.
Seismic Velocity
Electrical
Conductivity
MassDensity
Flow
Strength
Partial Melt
Hot?Wet?
Slow
High
Cold?Dry?
Fast
Low
!
!
These arethe oneswe need formodeling.
From Becker, Lowry, et al., Nature, 2015
Earthquake Distribution Gravitational Potential Energy Crustal Thickness
Lithosphere Strength Seismic Lithosphere Depth Dynamic Topography
Becker, Lowry, et al., Nature, 2015
Wait… Dynamic topography? What is that?
Dynamic Topography
Schmandt & Lin, GRL, 2014 Becker, Lowry, et al., Nature, 2015
Then serendipity strikes…
Bec
ker,
Low
ry, e
t al.,
Nat
ure,
201
5
Random at
95 %confidence
Bec
ker,
Low
ry, e
t al.,
Nat
ure,
201
5
Bec
ker,
Low
ry, e
t al.,
Nat
ure,
201
5
And what does it mean for earthquakes?Our model neglected the lithosphere:
But in reality “dynamic elevation rate” is better thought of as a“lithospheric loading rate”
that adds to membrane stress and stretching of thelithosphere.
High viscosity fluid
Low viscosity fluid
Visco-elasto-plastic lithosphere
“Uplift”
So where does water come into this?
“Dry” mantle peridotite “Hydrous” mantle serpentinite
How would water get there?
Kanda et al., in prep, 2015
Wannamaker et al., Nature, 2009
Schmandt & Lin, GRL, 2014
Higher H2O
Property Higher Temp.
Seismic Velocity
Electrical
Conductivity
MassDensity
Flow
Strength
Partial Melt
Te and StrengthBritt
le Stre
ngth
Flow
Crust
Mantle
zn
f
YSE
Elastic
Inviscid
zn
f
Flow Strength…
depends on:• Temperature• Rock Type (pyroxene > olivine > feldspar > quartz)
• Water Content.
Crust
Mantle
Flow Strength…
depends mostly on:
• Rock Type (crust thickness)• Temperature
• Water Content
Flow Strength…
depends mostly on:
• Rock Type (Qtz or Fsp?)• Temperature
• Water Content
Flow Strength…
depends mostly on:
• Rock Type
• Temperature
• Water Content
Flow Strength…
depends mostly on:
• Rock Type
• Temperature
• Water Content
Wet (saturated) end-member Dry end-member
Bec
ker,
Low
ry, e
t al.,
Nat
ure,
201
5
Thank You
Inte
rmou
ntai
n S
eism
ic B
elt
Electrical Conductivity Seismic Velocity
Electrical conductivity structure is dominantly water variation below ~200 km depth…
But difficult to interpret at shallower depths, even when coupled with seismic imaging
Schmandt & Lin, GRL, 2014
Meq
bel e
t al.,
EP
SL,
201
4