Conveners: Kaj Johnson, Liz Hearn, David Sandwell, and Wayne Thatcher
Dates: April 1-2, 2010
Location: Kellogg West Conference Center and Lodge, Pomona, CA
Participants: 42 total (view list of attendees)

WORKSHOP REPORT: Download workshop report

SUMMARY: The purpose of the workshop is to begin scientific consideration of how to incorporate GPS constraints on strain rates and fault slip rates into the next generation California earthquake hazard assessment ("UCERF3"). A principal outcome of the meeting will be (1) an assessment of secure science ready for UCERF3 applications, and (2) an agenda of new research objectives for SCEC in support of UCERF3 and related probabilistic hazard assessments.

The format of the workshop includes three topical sessions, with limited number of invited presentations scheduled and lots of open discussion time, and an evening poster session. Time is allotted for groups to discuss main scientific issues:

• Earthquake cycle deformation and influence of postseismic transients


• Strain rate map methodologies and issues


• Block modeling methodologies and GPS fault slip rate estimation


• Reconciliation of differing GPS fault slip and strain rate estimates

All participants were requested to submit poster presentation. A small number of short (~5 minute) presentations were solicited from the submitted poster abstracts.

Actual (e.g. SCEC CMM4 GPS field) or synthetic test data sets were distributed prior to the workshop for modeling test cases. Kinematic and dynamical fault modelers, strain rate mappers, and block modelers thus were able to run their codes to supply outputs for discussion at the workshop.

DAY 1: Thursday, April 1, 2010

Introductory Remarks
08:00 Workshop goals, format, and desired outcomes (Wayne Thatcher)
08:20 Purpose of UCERF3 and potential role of space geodesy (Ned Field)
08:40 Questions and Discussion

Session 1. Strain Rate Mapping Methodologies and Issues (Chair: David Sandwell)
09:00 The science of constructing strain rate maps (David Sandwell)
09:30 Open Discussion
10:00 Selected Short Contributions (each 5 mins max, Hammond, Smith-Konter, Loveless, Shen, and Tom Herring)

10:30 Break

10:45 Results of community modeling exercise (summary by David Sandwell)
11:15 Open Discussion of community modeling results (Participants: Thorsten Becker, Peter Bird, Andy Freed, Jack Loveless, Bill Holt, Sharon Kedar, Cornee Kreemer, Rob McCaffrey, Fred Pollitz, Bridget Smith-Konter, Carl Tape, Yuehua Zeng)

12:00 Lunch

Session 2. GPS Fault Slip Rate Estimation from Block Models (Chair: Kaj Johnson)
13:00 Block modeling overview (Kaj Johnson)
13:15 Fault geometry and elastic block models (Brendan Meade)
13:30 NeoKinema Model predictions for California strain and slip rates (Peter Bird)
13:45 Open Discussion
14:15 Selected Short Contributions (each 5 mins max, Laura Wallace, Takeshi Sagiya, Wayne Thatcher, and Yuehua Zeng)

14:45 Break

15:00 Selected Short Contributions (each 5 mins max, Rob McCaffrey, Bill Hammond/Jayne Bormann)
15:15 Results of community modeling exercise (summary by Kaj Johnson)
15:30 Open Discussion of community modeling results

16:00 Breakout sessions
--Effect of transients and elastic heterogeneity on earthquake cycle deformation
--GPS slip rate estimation: Secure science and new research directions
--Strain rate field estimation: Secure science and new research directions

17:00 Adjourn

18:00 Dinner

19:00 Poster Session (2 hours)

DAY 2: Friday, April 2, 2010

Session 3. Earthquake Cycle and Other Effects on Interseismic Deformation (Chair: Liz Hearn)
08:00 How much do earthquake cycles effects influence geodetic estimates of stressing and fault slip rates? (Liz Hearn)
08:30 Physics-based models of interseismic deformation: What physics is relevant? (Yuri Fialko)
09:00 Open Discussion
09:30 Selected Short Contributions (each 5 mins max, Gina Schmalze, Brad Hager)

10:00 Break

10:30 Results of community modeling exercise (summary by Liz Hearn) (Participants: Hetland, Meade, Smith-Konter, Johnson, Fialko, Hearn)
11:00 Open Discussion of community modeling results
11:30 Reports of breakout group chairs
--Effect of transients and elastic heterogeneity on earthquake cycle deformation
--GPS slip rate estimation: Secure science and new research directions
--Strain rate field estimation: Secure science and new research directions

12:00 Lunch

13:00 Invited Presentation: Geologic slip rate estimation (Ray Weldon)
13:30 Discussion: Geologic and GPS slip rates -- What next?

14:00 Wrap-Up Session: Directed Discussion (Wayne Thatcher, Kaj Johnson, Liz Hearn, David Sandwell)
--Next steps for reconciling strain rate maps
--Next steps for reconciling geodetic estimates of fault slip rate

15:00 Workshop Adjourn

15:30 Conveners meet to draft Workshop Summary (1.5 hours)