workshop on fault segmentation and fault-to-fault jumps in earthquake rupture (march 15-17, 2006)...

Workshop on

Fault Segmentation and Fault-To-Fault Jumps in Earthquake Rupture

(March 15-17, 2006)

Convened by

Ned Field, Ray Weldon, Ruth Harris, David Schwartz, & David Oglesby

on behalf of the WGCEP (http://www.WGCEP.org)

Agenda

Weds & Thurs:

Hear from experts and discuss

Friday:

Decide what WGCEP should do

Workshop Goals

To determine the spatial extent of all possible earthquakes on explicitly modeled faults in California

(reevaluate current segmentation models and explore alternatives)

time dependence at

a future workshop

Working Group on California Earthquake Probabilities

(WGCEP)

Development of a

Uniform California Earthquake Rupture Forecast

(UCERF)

To provide the California Earthquake Authority (CEA) with a statewide, time-dependent ERF that uses “best available science” and is endorsed by the USGS, CGS, and SCEC, and is evaluated by Scientific Review Panel (SRP) and CEPEC

Coordinated with the next National Seismic Hazard Mapping Program (NSHMP) time-independent model

CEA will use this to set earthquake insurance rates (they want 5-year forecasts, maybe 1-year in future)

WGCEP Goals:

Funding:

Most from CGS, SCEC, & USGS

$1,750,000 from CEA (22% of total)

NSF

CEA

USGS

CGS

SCEC

MOC

State of CA

USGS Menlo Park

USGS Golden

Sources of WGCEP funding

Geoscience organizations

Management oversightcommittee

WGCEPExCom

Subcom.A

Subcom.B

Subcom.C

…

…

Working group leadership

Task-oriented subcommittees

Working Group on California Earthquake

Probabilities

WGCEP Organization

& Funding Sources

SCEC will provide CEA with a single-point interface to the project.

SRP

Scientific reviewpanel

WGCEP Management Oversight Committee (MOC):

SCEC Thomas H. Jordan (CEA contact)USGS, Menlo ParkRufus Catchings USGS, Golden Jill McCarthy CGS Michael Reichle

WGCEP Management:

In charge of resource allocation and approving all project plans, budgets, and schedules

Their signoff will constitute the SCEC/USGS/CGS endorsement

Responsible for convening experts, reviewing options, making decisions, and orchestrating implementation of the model and supporting databases

Role of leadership is not to advocate models, but to accommodate whatever models are appropriate

WGCEP Executive Committee:

Edward (Ned) Field; SCEC/USGS, Pasadena Thomas Parsons, USGS, Menlo Park Chris Wills, CGS Ray Weldon, SCEC/UofO Mark Petersen, USGS, Golden Ross Stein, USGS, Menlo Park

Key Scientists:

Provide expert opinion and/or specific model elements - likely receiving funding & documenting their contributions.Contributors

Scientific Review Panel:

Bill Ellsworth (chair)Art FrankelDavid JacksonJim DieterichLloyd CluffAllin CornellMike BlanpiedDavid Schwartz

CEPEC:

Lucile Jones Duncan AgnewTom Jordan Mike ReichleJim Brune David OpenheimerWilliam Lettis Paul SegallJohn Parrish

This group will ultimately decide whether we’ve chosen a minimum set of alternative models that adequately spans the range of viable 5-year forecasts for California

BlackBox

Deformation

Model(s)

Earthquake Prob Model(s)

Earthquake Rate Model(s)

BlackBox

BlackBox

(A)

(B)

(C)

(D)

UCERF Model ComponentsFaultModel(s)

Fault-slip rates & Aseismicity Estimates(at least)

Long-term rate of all possible events (on and off modeled faults)

Time-dependent probabilities

Geometries (& alternatives)

BlackBox

Deformation

Model(s)



BlackBox

BlackBox

(A)

(B)

(C)

(D)

FaultModel(s)

Fault Section Database

Paleo Sites

Database

GPS Database

Historical Qk

Catalog

Instrumental Qk Catalog

UCERF Model Components

Main Delivery Schedule

February 8, 2006 (to CEA)

UCERF 1 &

Aug 31, 2006 (to CEA)

Earthquake Rate Model 2 (preliminary for NSHMP)

June 1, 2007 (to NSHMP)

Final, reviewed Earthquake Rate Model 2(for use in 2007 NSHMP revision)

September 30, 2007 (to CEA)

UCERF 2 (reviewed by SRP and CEPEC)

1) Statewide model

2) Use of SCEC CFM (including alternatives)

3) Use GPS data via kinematically consistent

deformation model(s)

4) Relax strict segmentation (if appropriate)

5) Allow fault-to-fault jumps (if appropriate)

6) Apply consistent time-dependent models (esp.

with (4) & (5))

7) Include earthquake triggering effects

8) Deploy as extensible, adaptive (living)

model.

9) Simulation enabled

Issues/Possible Innovations

1988 1990 1995

2002

UCERF

1) Statewide model


WGCEPs:

2) Use of SCEC Community Fault Model

(including alternatives)


3) Use GPS data via kinematically consistent

deformation model(s)


e.g., Peter Bird’s NeoKinema

BlackBox

Deformation

Model(s)



BlackBox

BlackBox

FaultModels(s

)

We want:

1) Improved slip rates on major faults2) Strain rates elsewhere3) GPS data included

GPS data from Geodesy group

4) Kinematically consistent5) Accommodate all important faults6) Can accommodate alternative fault models7) Accounts for geologic and geodetic data uncertainties8) Includes viscoelastic effects9) Includes significant 3D effects10) Statewide application

BlackBox

Deformation

Model(s)



BlackBox

BlackBox

FaultModels(s

)

We want:

1) Improved slip rates on major faults2) Deformation rates elsewhere3) GPS data included4) Kinematically consistent5) Accommodate all important faults6) Can accommodate alternative fault models7) Accounts for geologic and geodetic data

uncertainties8) Includes viscoelastic effects9) Includes significant 3D effects10) Statewide application

Are any existing models better than sticking to what we have?

WGCEP recommending pursuit of:NeoKinema

Harvard-MIT Block ModelParson’s FEMShen & ZengPerhaps others …

No model has all these attributes

BlackBox

Deformation

Model(s)



BlackBox

BlackBox

FaultModels(s

) Are any existing models better than sticking to what we have?

WGCEP recommending pursuit of:NeoKinema

Harvard-MIT Block ModelParson’s FEMShen & ZengPerhaps others …

No model has all these attributes

Delivery will be revised slip rates on modeled faults (and perhaps deformation rates elsewhere, and stressing rates on faults)

4) Relax strict segmentation


All previous WGCEPs have assumed strict segmentation, more recently allowing both single- and multi-segment ruptures (cascades).

e.g., WGCEP-2002:



But ...

Viable interpretations of S. SAF paleoseismic data (Weldon et al.)



Does it matter (all models are discretized to some extent)?

SJF; SB-SJV segment intersectionSAF: Mojave-San Bernardino intersection

50% in 50 yrs

5) Allow fault-to-fault jumps


No previous WGCEPs have allowed such ruptures.



But ...



Fault Interactions and Large Complex Earthquakes in the Los Angeles Area

Anderson, Aagaard, & Hudnut (2003, Science 320, 1946-1949)

“… We find that … a large northern San Jacinto fault earthquake could trigger a cascading rupture of the Sierra Madre-Cucamonga system, potentially causing a moment magnitude 7.5 to 7.8 earthquake on the edge of the Los Angeles metropolitan region.



Can dynamic rupture modelers help define fault-to-fault jumping probabilities?

6) Figure out how to apply elastic-rebound-

motivated renewal models “properly”


Problem: how to compute conditional time-dependent probabilities when you allow both single and multi-segment ruptures (let alone relaxing segmentation)?

There seems to be a logical inconsistency with the way previous WGCEPs have modeled this …

Example of a long-term, moment balanced rupture model for the Hayward/Rodgers-Creek fault, obtained from the WGCEP-2002 Fortran code.

Segment Info

Name Length (km)

Width (km)

slip-rate (mm/yr)

Rupture Rate (/yr)

Date of Last

Event RC 52.54 12 9 3.87e-3 1868 HN 34.89 12 9 3.95e-3 1702 HS 62.55 12 9 4.08e-3 1740

Rupture Info Name mag rate HS 7.00 1.28e-3 HN 6.82 1.02e-3 HS+HN 7.22 2.16e-3 RC 7.07 3.32e-3 HN+RC 7.27 0.32e-3 HS+HN+RC 7.46 0.44e-3 floating 6.9 0

From WGCEP-2002:

The BPT distribution of recurrence intervals used to compute segment rupture probabilities (red line), as well as the distribution of segment recurrence intervals obtained by simulating ruptures according the WGCEP-2002 methodology (gray bins). The BPT probabilities assume a coefficient of variation of 0.5 and the given segment rates. Note the relatively high rate of short recurrence intervals in the simulations.

From WGCEP-2002:

How then do we compute conditional probabilities where we have single and multi-segment ruptures?

We have ideas …

7) Include earthquake triggering effects


CEA wants 1- to 5-year forecasts

This is between the 30-year forecasts of previous WGCEPs (renewal models) and the 24-hour forecasts of STEP (the CEPEC-endorsed model based on aftershock statistics)We are attempting to design a framework that could accommodate a variety of alternative approaches (e.g., from RELM)

8) Deploy as extensible, adaptive (living)

model.


i.e., modifications can be made as warranted by scientific developments, the collection of new data, or following the occurrence of significant earthquakes. The model can be “living” to the extent that update & evaluation process can occur in short order.

CEA wants this.

9) Simulation enabled (i.e, can generate

synthetic catalogs)


Needed to go beyond next-event forecasts if stress interactions and earthquake triggering are included

Helpful (if not required) to understand model behavior

Can be used to calibrate the model (e.g., % moment in aftershocks)

If we can deal with simulated events, we’ll be ready for any real events

Implementation Plan

Guiding principles:

•If it ain’t broke, don’t fix it•Some of the hoped-for innovations won’t work out

•Everything will take longer than we think

•Build components in parallel (not in series)

•Get a basic version of each component implemented ASAP, and add improved versions when available

We cannot miss the NSHMP and CEA delivery deadlines!

BlackBox

Deformation

Model 1.0

Earthquake Prob Model 1.0

Earthquake Rate Model 1.0

BlackBox

BlackBox

FaultModel 1.0

UCERF 1.0NSHMP-2002 Fault Model

NSHMP-2002Fault Slip Rates NSHMP-2002

Earthquake Rate Model

Simple conditional probabilities based on date of last earthquakes

By Feb. 8, 2006

BlackBox

Deformation

Model 2.0



BlackBox

BlackBox

FaultModels 2.X

UCERF 2.0Revision of NSHMP-2002 Fault Model

based on SCEC CFM (including

alternatives) & any desired changes for N. California

Revised slip rates for elements in Fault Model 2.0, perhaps constrained by GPS data.

New model based on reevaluation of fault

segmentation and cascades (e.g., based on Weldon et

al.); may relax segmentation

and allow fault-to-fault

jumps.

Application of more sophisticated time-dependent probability calculations

We can at least deliver this for the NSHMP 2007 time-independent hazard maps(by June 1, 2007)& This to

CEA

By Sept. 30, 2007

BlackBox

Deformation

Model 3.0



BlackBox

BlackBox

FaultModels 2.X

UCERF 3.0

e.g., relax segmentation, allow fault-to-fault

jumps, and use off-fault deformation rates to help

constrain off-fault seismicity.

e.g., enable real-time modification of probabilities base on stress or seismicity-rate changes.

Use of a more sophisticated, California- wide deformation model such as NeoKinema.

BlackBox

Deformation

Model 3.0



BlackBox

BlackBox

FaultModels 2.X

UCERF 3.0

e.g., relax segmentation, allow fault-to-fault

jumps, and use off-fault deformation rates to help

constrain off-fault seismicity.

e.g., enable real-time modification of probabilities base on stress or seismicity-rate changes.

Use of a more sophisticated, California- wide deformation model such as NeoKinema.

All of these are relatively ambitious and delivery cannot be guaranteed by 2007.

Agenda

Weds & Thurs:

Hear from experts and discuss

Friday:

Decide what WGCEP will do

Workshop Goals

To determine the spatial extent of all possible earthquakes on explicitly modeled faults in California

(reevaluate current segmentation models and explore alternatives)

“Co-Seismic”?

What’s the difference between “co-seismic” and “triggered quickly”?

1) Constructive interference (e.g., directivity)

2) My Earthquake Insurance:

“One or more earthquake shocks that occur within a seventy-two hour period constitute a single earthquake”

3) California Earthquake Authority:

“seismic event” = everything within a 15-day window

Current Practice

(WGCEP-2002, NSHMP-2002, UCERF 1)

******************

NSHMP-2002 & UCERF 1Southern California Type A Faults

= 0.12Trunc +/-1.25

NSHMP-2002 Bay Area Faults& WGCEP-2002

= 0.12Trunc +/-2

NSHMP-2002 B Faults & UCERF 1

2/3 Mo Char1/3 Mo GR

An Alternative Approach(?)

(extension of Andrews & Schwerer (2000) w/ elements of Field et al. (1999))

1) Divide faults into small sections (~5 to ~10 km in length)2) Define “all possible ruptures” as every possible combination of “contiguous” sections (“contiguous” means separated by less than ~10 km)

Use matrix Irs to indicate whether rth rupture involves the sth segment

3) Get magnitude of each rupture from mag(area) relationship; this gives average slip (ur) of each as well

4) Solve for the long term rate of each rupture (fr) via linear inversion of:


f(m) = GR (for entire region)

€

I rsr

∑ fr = fs (e.g., trench constraint)

fr ≥ 0 (positivity for all r)

€

Irs

r

∑ ur f r = vs (moment balance)

Anything else (e.g., rupture boundaries) …

Solution space represents all possible models

fr = fobs (e.g., Parkfield)

A formal, tractable, extensible, mathematical framework

What can geology or dynamic modeling tell us about what ruptures are more or less probable?


How do we define and apply these constraints in our inversion?Have the simulators solved this problem?


(extension of Andrews & Schwerer (2000) w/ elements of Field et al. (1999))

1) Divide faults into small sections (~5 to ~10 km in length)2) Define “all possible ruptures” as every possible combination of “contiguous” sections (“contiguous” means separated by less than ~10 km)

Use matrix Irs to indicate whether rth rupture involves the sth segment

3) Get magnitude of each rupture from mag(area) relationship; this gives average slip (ur) of each as well

4) Solve for the long term rate of each rupture (fr) via linear inversion of:


f(m) = GR (for entire region)

€

I rsr

∑ fr = fs (e.g., trench constraint)

fr ≥ 0 (positivity for all r)

€

Irs

r

∑ ur f r = vs (moment balance)

Anything else (e.g., rupture boundaries) …

Solution space represents all possible models

fr = fobs (e.g., Parkfield)

A formal, tractable, extensible, mathematical framework


How do we define and apply these constraints in our inversion?Have the simulators solved this problem?

workshop on fault segmentation and fault-to-fault jumps in earthquake rupture (march 15-17, 2006)...

Documents

earthquake rupturemarch

jordan cea contact usgs

cgs ray weldon

earthquake insurance

alternativesworking

scec thomas

year forecasts

current segmentation