Numerical Modeling Using Finite Difference Techniques

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Numerical Modeling Using Finite Difference
Techniques
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Modeling of Wave Propagation and Ground Motion
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M7.3 1992 Landers
M6.7 1994 Northridge

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1992 Landers

When 28 June 1992 Where Mojave
Desert Damage 56 million Deaths 1 Injured
gt400
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1994 Northridge

When 17 Jan 1994 Where San Fernando
Valley Damage 20 billion Deaths
57 Injured gt9000
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ObjectiveMitigate loss of life and property in
future large events

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Subsurface Model

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M7.5 San Andreasfrom south-east Fault-parallel

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M7.5 San Andreasfrom north-west
Fault-parallel

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3D/1D peak velocity ratios

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Validation 1994 Northridge

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• Wavefield Separation

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Modeling of Earthquake Rupture Dynamics
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Dynamic Rupture From Trial-and-Error
Finite-Difference Modeling

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Inverted (Trial-and-Error) Dynamic Radiation
Versus Data

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Modeling of Stress Transfer/Triggering
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Static Coulomb Failure Stresses Dsf among
others, Das Scholz, 1981 Harris et al.,
1991 Stein, 1999
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• However
• Dsf does not explain all observations
• e.g.,
• 1943 North Anatolian Fault event
• More aftershocks in direction of rupture
  
• propagation (for example, 1992 Landers)
• Sometimes aftershocks in the stress shadow

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Dynamic Coulomb Failure Stresses Dsf(t) Kilb et
al., 2002 Kilb, 2003
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Illustration of Dsf(t)

North Anatolian Fault 1944 Event
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Components of Dsf(t)
peakDsf(t)
Dsf(t)
Dts(t)
Dsn(t)
Dsf(t)
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Effect of Rupture Direction
peakDsf(t)
Dsf(t)
Toward the West
Bi-lateral
Toward the East
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Effect of Rupture Velocity
Dsf(t)
peakDsf(t)
Sub-shear
Super-shear
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North-Anatolian Fault, Turkey
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West-ward propagating series of events on the
North Anatolian Fault 1939-1999
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North Anatolian Fault Sequence 1939-1999
N
300 km
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Seismic Exploration