Unified California geodesy

1
Deformation modeling in support of earthquake
Probability calculations (WGCEP 11/17/5)

• Unified California geodesy
• Fault slip rate models
• Stressing rate and interaction models

2
Why do we want deformation models?
Like every working group, we have to interpret
geologic information, fill in gaps, and
estimate fault slip rates Can we use geodesy
and numerical modeling as tools to make
estimates with quantified uncertainties? Non-uni
que solutions and different strategies require
multiple models
3
All data are in a consistent North America
reference frame
4
(No Transcript)
5
(No Transcript)
6
(No Transcript)
7
(No Transcript)
8
(No Transcript)
9
Deformation modeling in support of earthquake
Probability calculations (WGCEP 11/17/5)

• A unified geodetic database is already compiled,
  and
• a full Q.C. version should be available soon
• Four block models are (or will be) available, and
  
• another is possible
• Two stressing rate models are published/in press

10
(No Transcript)
11
(No Transcript)
12
Uncertainty in stress-change calculation
Interaction probability calculation
Empirical methods Theoretical methods
Significance of impact on probability is
situational, depending on magnitude, time, local
characteristics, and methodology
13
The Aftershock Models
model complexity
Generic California Model
lowest
Generic parameters calculated using California
aftershock sequences (1932-1987) Only requires
mainshock magnitude as input
California aftershock rates (1988-2003) vs.
Generic model
14
The Aftershock Models
model complexity
Sequence Specific Model
medium
needs minimum of 100 aftershocks before
estimating parameters One set of model parameters
(Gutenberg-Richter and modified Omori laws)
calculated for the entire aftershock sequence
The aftershock zone
15
The Aftershock Models
model complexity
Spatially Varying Model
highest
Gutenberg-Richter and modified Omori law
parameters are mapped at 5km spacing
1989 M6.9 Loma Prieta, California
16
Have forecasts from 3 models but can only use 1
for the hazard forecast!!
Spatially Varying Model
Final Forecast of number of earthquakes
Akaike Information Criterion
Sequence Specific Model
Generic California Model

• number of free parameters (how many ways the
  model can be adjusted)
• sample size (number of events)
• prefers fewer free parameters -gt a more complex
  model must fit the data better to be weighted the
  same as a more simple model

17
(No Transcript)
18
(No Transcript)
19
(No Transcript)
20
Uncertainty in stress-change calculation
Interaction probability changes
Probability change time, space, method
variable Need a basis for weighting different
methods