Triggering a perturbation in the loading deformation that leads to a change in the probability of fa

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Overview of Evidence for Dynamic Triggering
Triggering a perturbation in the loading
deformation that leads to a change in the
probability of failure.
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Triggering a perturbation in the loading
deformation that leads to a change in the
probability of failure. How do we know it
happens?
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Triggering a perturbation in the loading
deformation that leads to a change in the
probability of failure. How do we know it
happens? Measure or infer a loading
perturbation, observe a change in seismicity
rate (fault population or single fault
recurrence), possibly its spatial variation too.
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The Reference State
Central California Ambient Seismicity
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The Perturbation
Coyote Lake Mainshock Ambient Seismicity
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The Perturbation Response
Coyote Lake Mainshock Aftershocks
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• Dynamic loads
• Seismic waves (oscillatory, transient)

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• Dynamic loads
• Seismic waves (oscillatory, transient)
• Aseismic slip (not oscillatory, may be
  permanent)

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• Dynamic loads
• Seismic waves (oscillatory, transient)
• Aseismic slip (not oscillatory, permanent)
• Solid earth tides and ocean loading
  (oscillatory, ongoing)

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• Dynamic loads
• Seismic waves (oscillatory, transient)
• Aseismic slip (not oscillatory, permanent)
• Tides (oscillatory, ongoing)
• Surface/shallow snow and ice, reservoir
  filling/draining, mining, ground water, fluid
  injection or withdrawal (localized)
• Magma movement (temperature, pressure, and
  chemical changes too)

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Whats unique about dynamic loads?
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Whats unique about dynamic loads? Theyre
transient!
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Static Load Change
Dt
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Static Load Change
Dt
failure threshold
Dt
shear stress
time
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Dynamic Triggering
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Dynamic Triggering
failure threshold
Dt
shear stress
time
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Whats unique about dynamic loads? Theyre
transient the failure conditions must change!
failure threshold
Dt
shear stress
time
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Whats unique about dynamic loads? Theyre
transient the failure conditions must
change! Theyre oscillatory, but they only
enhance failure probability (ASSUMPTION) no
stress shadows.
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Whats unique about dynamic loads? Theyre
transient the failure conditions must
change! They only enhance failure probability
(ASSUMPTION) no stress shadows. Slower distance
decay than static stress changes.
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Dynamic Triggering Observations (by load
type) Seismic waves (transient,
oscillatory) Remote (many source
dimensions) Near-field (few source dimensions)
Distance-independent Quasi-seismic
responses Laboratory Aseismic slip (slow,
permanent) Tides (oscillatory,
ongoing) Surface/Shallow snow and ice,
reservoir filling/draining, mining, ground
water, fluid injection or withdrawal (localized)
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Dynamic Triggering Observations (by loading
type) Seismic waves Remote (many source
dimensions) Seismicity rate increases following
large earthquakes.
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Dynamic Triggering Observations (by loading
type) Seismic waves Remote (many source
dimensions) Seismicity rate increases following
large earthquakes.
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Dynamic Triggering Observations (by loading
type) Seismic waves Remote (many source
dimensions) Seismicity rate increases following
large earthquakes.
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Dynamic Triggering Observations (by loading
type) Seismic waves Remote (many source
dimensions) Seismicity rate increases following
large earthquakes. Missing? rate increases.
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Dynamic Triggering Observations (by loading
type) Seismic waves Remote (many source
dimensions) Near-field (few source dimensions)
Correlation of spatial rate increase with
directivity.
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Dynamic Triggering Observations (by loading
type) Seismic waves Remote (many source
dimensions) Near-field (few source dimensions)
Correlation of spatial rate increase with
directivity. Correlation of (no) rate change
with co-located seismic aseismic events.
Pollitz Johnston, 2007
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Dynamic Triggering Observations (by loading
type) Seismic waves Remote (many source
dimensions) Near-field (few source dimensions)
Correlation of spatial rate increase with
directivity. Correlation of (no) rate change
with co-located seismic aseismic events.
Pollitz Johnston, 2007
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Dynamic Triggering Observations (by loading
type) Seismic waves Remote (many source
dimensions) Near-field (few source dimensions)
Correlation of spatial rate increase with
directivity. Correlation of (no) rate change
with co-located seismic aseismic events.
Early excess of aftershocks. Rate increases
in stress shadows.
Chi-Chi earthquake shadows start with 3-month
rate increases.
Ma et al., 2005
1998 1999 2000 2001
2002
1998 1999 2000 2001
2002
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Observed seismicity rate decreases in the Santa
Monica Bay and along parts of the San Andreas
fault are correlated with the calculated stress
decrease. Stein, 1999
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Observed seismicity rate decreases in the Santa
Monica Bay and along parts of the San Andreas
fault are correlated with the calculated stress
decrease. Stein, 1999
Time history of seismicity from Santa Monica Bay
(Marsan, 2003).
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The Stein, 1999 interpretation is made
difficult by the fact that the transient activity
modulation by the 1989 M5 Malibu earthquake was
still ongoing.the quiescence observed after 1994
can be tracked back several months before
Northridge, the latter main shock actually
triggering seismicity in the region at the very
short (i.e. days) timescale. Marsan, 2003
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Dynamic Triggering Observations (by loading
type) Seismic waves Remote (many source
dimensions) Near-field (few source dimensions)
Distance-independent view
Measured Linear Aftershock Densities
Felzer Brodsky, 2006
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Dynamic Triggering Observations (by loading
type) Seismic waves Remote (many source
dimensions) Near-field (few source dimensions)
Distance-independent view
Modeled Linear Aftershock Densities
g constant!
number of aftershocks at distance r
number of potential nucleation sites per unit
distance
probability of nucleation
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Dynamic Triggering Observations (by loading
type) Seismic waves Remote (many source
dimensions) Near-field (few source dimensions)
Distance-independent view
Modeled Linear Aftershock Densities
g constant!
number of aftershocks at distance r
number of potential nucleation sites per unit
distance
probability of nucleation
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Dynamic Triggering Observations (by loading
type) Seismic waves Remote (many source
dimensions) Near-field (few source dimensions)
Distance-independent view
triggering fault
D
Linear density number of aftershocks within a
volume defined by surface S everywhere at
distance r and width Dr
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Dynamic Triggering Observations (by loading
type) Seismic waves Remote (many source
dimensions) Near-field (few source dimensions)
Distance-independent view
Modeled Linear Aftershock Densities
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Dynamic Triggering Observations (by loading
type) Seismic waves Remote (many source
dimensions) Near-field (few source dimensions)
Distance-independent view
Modeled Linear Aftershock Densities
g constant!
number of aftershocks at distance r
number of potential nucleation sites per unit
distance
probability of nucleation
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Dynamic Triggering Observations (by loading
type) Seismic waves Remote (many source
dimensions) Near-field (few source dimensions)
Distance-independent view
Modeled Linear Aftershock Densities
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Dynamic Triggering Observations (by loading
type) Seismic waves Remote (many source
dimensions) Near-field (few source dimensions)
Distance-independent view
Modeled Linear Aftershock Densities
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Dynamic Triggering Observations (by loading
type) Seismic waves Remote (many source
dimensions) Near-field (few source dimensions)
Distance-independent view
Are dynamic deformations consistent with these
probabilities?
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Dynamic Triggering Observations (by loading
type) Seismic waves Remote (many source
dimensions) Near-field (few source dimensions)
Distance-independent view
Are dynamic deformations consistent with these
probabilities?
Peak Velocities vs r, M5.5-7.0
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Dynamic Triggering Observations (by loading
type) Seismic waves Remote (many source
dimensions) Near-field (few source dimensions)
Distance-independent view
Are dynamic deformations consistent with these
probabilities?
Peak Velocities vs r, M5.5-7.0
Peak Velocities vs r/D, M5.5-7.0
perhaps!
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Dynamic Triggering Observations (by loading
type) Seismic waves Remote (many source
dimensions) Near-field (few source dimensions)
Distance-independent view Quasi-seismic
responses Low-frequency events
Sumatra surface waves in Japan
High-passed Sumatra surface waves in Japan
Correlation with Rayleigh waves - Dilatation
Fluids
Miyazawa Mori, 2006
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Dynamic Triggering Observations (by loading
type) Seismic waves Remote (many source
dimensions) Near-field (few source dimensions)
Distance-independent view Quasi-seismic
responses Low-frequency events
Sumatra surface waves in Japan
Denali surface waves in Japan, Correlation with
Love waves - Shear Load!
High-passed Sumatra surface waves in Japan
Correlation with Rayleigh waves - Dilatation
Fluids
Miyazawa Mori, 2006
Rubinstein et al., 2007
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Dynamic Triggering Observations (by loading
type) Seismic waves Remote (many source
dimensions) Near-field (few source dimensions)
Distance-independent view Quasi-seismic
responses Low-frequency events
Creep and tilt
Response to Hector Mine waves on Imperial Fault
(260 km)
H
H
Glowacka et al., 2002
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Dynamic Triggering Observations (by loading
type) Seismic waves Remote (many source
dimensions) Near-field (few source dimensions)
Distance-independent view Quasi-seismic
responses Laboratory
Granular surface quasi-static experiments.
Our results predict that a transient dynamic
normal load during creep can strengthen a
faultgouge particles become compacted into a
lower energy configuration. Richardson and
Marone, 1999
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delayed failure
Dynamic Triggering Observations Seismic waves
Remote (many source dimensions) Near-field (few
source dimensions) Distance-independent view
Quasi-seismic responses Laboratory
delayed failure
Granite surface stick-slip experiments.
Sobolev et al., 1996
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delayed failure
Dynamic Triggering Observations Seismic waves
Remote (many source dimensions) Near-field (few
source dimensions) Distance-independent view
Quasi-seismic responses Laboratory
delayed failure
Vibration Clock-advances Failure
Granite surface, shear vibration, stick-slip
experiments.
Sobolev et al., 1996
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Dynamic Triggering Observations Seismic waves
Remote (many source dimensions) Near-field (few
source dimensions) Distance-independent view
Quasi-seismic responses Laboratory
Granular surface, acoustic vibration, stick-slip
experiments.
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Dynamic Triggering Observations Seismic waves
Remote (many source dimensions) Near-field (few
source dimensions) Distance-independent view
Quasi-seismic responses Laboratory
triggered new seismic events
triggered new seismic events
clock-delayed failure
acoustic transient
acoustic transient
Granular surface, acoustic vibration, stick-slip
experiments.
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Dynamic Triggering Observations Seismic waves
Remote (many source dimensions) Near-field (few
source dimensions) Distance-independent view
Quasi-seismic responses Laboratory
triggered new seismic events
memory
clock-delayed failure
acoustic transient
acoustic transient
Granular surface, acoustic vibration, stick-slip
experiments.
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Dynamic Triggering Observations (by loading type)
Seismic waves Aseismic slip Earthquakes
Hawaii Slow Slip Earthquakes
Number of earthquakes displacement
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Dynamic Triggering Observations (by loading type)
Seismic waves Aseismic slip Earthquakes
Tremor
Cascadia Slow Slip Tremor
Geodetic Displacement (mm east)
Tremor Activity (hrs in 10 days)
Dragert et al., 2002
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• General features
• apparent more commonly in areas of
• geothermal Quaternary to recent volcanism,
• extensional regimes,
• high strain rates,
• seismic strains required mstrains,
• sometimes instantaneous but also delayed.

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Models Coulomb-Navier failure no
delays Frictional traditional clock-advance
models cant explain long delays, require high
(near lithostatic) pressures or critical
conditions, changing frictional properties or
stability regime. Subcritical crack growth same
behavior as rate-state friction. Dynamic
nonlinear softening. Fluid and pore pressure
mechanisms decrease effective normal
stress, local, fluid-driven deformation disruption
of clogged fractures and hydraulic
fracturing bubbles rectified diffusion (volatiles
selectively pumped into bubbles during the
dilatation) advective overpressure (rising of
loosened bubbles within magma body )
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Models Coulomb-Navier failure no
delays Frictional traditional clock-advance
models cant explain long delays, require high
(near lithostatic) pressures or critical
conditions, changing frictional properties or
stability regime. Subcritical crack growth same
behavior as rate-state friction. Dynamic
nonlinear softening. Fluid and pore pressure
mechanisms decrease effective normal
stress, local, fluid-driven deformation disruption
of clogged fractures and hydraulic
fracturing bubbles rectified diffusion (volatiles
selectively pumped into bubbles during the
dilatation) advective overpressure (rising of
loosened bubbles within magma body )
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Dynamically reduced contact area (i.e. critical
slip distance)
Power-law distribution of contact areas.
Parsons, 2005
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Dynamically reduced contact area (i.e. critical
slip distance)
Power-law distribution of contact areas.
Number of events vs clock-advance for 10
reduction in critical slip distance.
Parsons, 2005
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Dynamically reduced contact area (i.e. critical
slip distance)
Number of events vs clock-advance for 10
reduction in critical slip distance.
Power-law distribution of contact areas.
Perturbed failure rate.
Parsons, 2005
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Models Coulomb-Navier failure no
delays Frictional traditional clock-advance
models cant explain long delays, require high
(near lithostatic) pressures or critical
conditions, changing frictional properties or
stability regime. Subcritical crack growth same
behavior as rate-state friction. Dynamic
nonlinear softening. Fluid and pore pressure
mechanisms decrease effective normal
stress, local, fluid-driven deformation disruption
of clogged fractures and hydraulic
fracturing bubbles rectified diffusion (volatiles
selectively pumped into bubbles during the
dilatation) advective overpressure (rising of
loosened bubbles within magma body )
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Models Coulomb-Navier failure no
delays Frictional traditional clock-advance
models cant explain long delays, require high
(near lithostatic) pressures or critical
conditions, changing frictional properties or
stability regime. Subcritical crack growth same
behavior as rate-state friction. Dynamic
nonlinear softening. Fluid and pore pressure
mechanisms decrease effective normal
stress, local, fluid-driven deformation, disruptio
n of clogged fractures and hydraulic
fracturing, bubbles rectified diffusion
(volatiles selectively pumped into bubbles during
the dilatation) advective overpressure (rising
of loosened bubbles within magma body).
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Elastic moduli decrease (soften) with increasing
dynamic load amplitude -gt weakening mechanism?
Relative Change in Modulus
Pulse Experiments, Glass Beads
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Elastic moduli decrease (soften) with increasing
dynamic load amplitude -gt weakening mechanism?
Relative Change in Modulus
Relative Change in Resonant Frequency
sinusoid amplitude (strain)
Sinusoid Experiments, Rocks
Relative Change in Modulus
Pulse Experiments, Glass Beads
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Models Coulomb-Navier failure no
delays Frictional traditional clock-advance
models cant explain long delays, require high
(near lithostatic) pressures or critical
conditions, changing frictional properties or
stability regime. Subcritical crack growth same
behavior as rate-state friction. Dynamic
nonlinear softening. Fluid and pore pressure
mechanisms decrease effective normal
stress, local, fluid-driven deformation, disruptio
n of clogged fractures and hydraulic
fracturing, bubbles rectified diffusion
(volatiles pumped into bubbles during the
dilatation), advective overpressure (rising of
loosened bubbles within magma body), liquefaction.

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-Outstanding Questions- Is our sampling biased
(e.g., best monitoring in high strain rate and/or
geothermal areas)?
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-Outstanding Questions- Is our sampling biased
(e.g., best monitoring in high strain rate and/or
geothermal areas)? How important are local
conditions are multiple mechanisms at work?
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-Outstanding Questions- Is our sampling biased
(e.g., best monitoring in high strain rate and/or
geothermal areas)? How important are local
conditions are multiple mechanisms at
work? What are the important characteristics of
the dynamic field (frequency/rate, duration, max.
value)?
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Strain Rate (acceleration)
Strain (velocity)
Displacement
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Velocity Strengthening, Slip Weakening Friction
Theoretical Frequency Sensitivity
Non-Linear, Slip Weakening Friction
Dynamically Induced Pore Pressure Change
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-Outstanding Questions- Is our sampling biased
(e.g., best monitoring in high strain rate and/or
geothermal areas)? How important are local
conditions are multiple mechanisms at
work? What are the important characteristics of
the dynamic field (frequency/rate, duration, max.
value)? How does delayed failure happen?
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Thanks! Comments?