of Slip in Surface Ruptures Glenn Biasi University of Nevada Reno 1 Glenn Biasi University of Nevada Reno Sinesqrt was the only shape used in UCERF 2 Shape from 13 events in HemphillHaley and Weldon ID: 393568
Download Presentation The PPT/PDF document "Task R1: Distribution" is the property of its rightful owner. Permission is granted to download and print the materials on this web site for personal, non-commercial use only, and to display it on your personal computer provided you do not modify the materials and that you retain all copyright notices contained in the materials. By downloading content from our website, you accept the terms of this agreement.
Slide1
Task R1: Distribution of Slip in Surface Ruptures
Glenn BiasiUniversity of Nevada Reno
1
Glenn Biasi University of Nevada RenoSlide2
--
Sinesqrt
was the only shape used in UCERF 2.
-- Shape from 13 events in Hemphill-Haley and Weldon
-- Redo analysis,
Wesnousky
dataset, normalize and stack…
<30 km ruptures >200 km ruptures All available-- Sinesqrt shape average works for all event subsets
<30 km
<30 km with reflections
>200 km
>200 km w. refl.
All ruptures
All w. refl.
Sin(x/2L)
Sqrt(sin(x/2L))
2
Glenn Biasi University of Nevada RenoSlide3
Example rupture profiles from Wesnousky (2008). Red line at average displacement
3
Glenn Biasi University of Nevada RenoSlide4
Paleoseismic Rupture Scenarios
New records since WGCEP
-
2:
Bidart
Fan Six events since ~1300 A.D., compared with five events since ~950 A.D.
Five to seven events at Coachella since ~900 A.D. vs. four at Indio since A.D. 1000.Seven new events at Frazier Park.AMS redating of Pallett Creek.Shorter period of complete records, greater variability in scenarios.Glenn Biasi University of Nevada Reno
4Slide5
Notes on Averaged Rupture Shapes
Average rupture shape affects which scenarios from pearl
-stringing
fit total displacement criteria. Feeds into
N
(M) vs. M.Proposed: Use an empirical L->
Davg regression instead of a fixed Hanks-Bakun (from Task R2?).Can average shape be used w/o removing the stress-drop?
1857 was here
Rupture Length (km)
5
Glenn Biasi University of Nevada RenoSlide6
Multiple-Fault and Multiple Section Ruptures
Geologic assessment of step-overs
should give clues to the mechanical linkage of faults.At subfault
ends:
Greater degrees of distributed displacement
Local r
otation and extensionExaggerated
displacement gradientsObliquity of GPS strain field to fault orientation may be useful.6Glenn Biasi University of Nevada RenoSlide7
7
Glenn Biasi University of Nevada Reno
Wesnousky, 2008
Wells and
Coppersmith
1994
12
events could contribute to this plotSlide8
Overlap Illustration (5%)
Glenn Biasi University of Nevada Reno
8Slide9
Considerations for UCERF-3
Displacements on shorter faults are out of proportion to their lengths.
Is this a general feature when Type B or C faults link?How do short faults “know” what displacement to have?
Up
to 12 ruptures are available to study it
Systematize slip gradients
at ends as inputs to other models. Re-stringing pearls would give one view of the MFD and rupture end points from paleoseismic data.
Alternate Length-Daverage relation would change ratio of long and short ruptures.9Glenn Biasi University of Nevada RenoSlide10
Finite-Fault Rupture Displacements
Finite-fault inversion: Seismic
data inverted for slip on the fault. Potential uses:
Rupture displacement with strike and depth.
Evaluation of overlap/tapering at fault-to-fault ruptures.
Pros and Cons
Depth filters out variability compared with near-surface measurements
Wavelengths may reflect larger, more important structuresInversions differ, sometimes even in gross structureSmoothing, resolution vary from earthquake to earthquakeAnalyses can be one plane or in sub-fault panelsResourceCompilation by Mai: 152 ruptures for 80 earthquakesGlenn Biasi University of Nevada Reno10Slide11
Glenn Biasi University of Nevada Reno
11Slide12
Finite-Fault Rupture Displacements
Evaluation approach
Develop slip differences in depth and horizontal separation (e.g., Shaw, 2010)Compare with min, max frequencies in inversion
Evaluate for patterns in slip and normalized slip
Compare with available surface slip
Recommend use (or not) in UCERF-3
Glenn Biasi University of Nevada Reno
12Slide13
Glenn Biasi University of Nevada Reno
13Slide14
Candidate ruptures to add to Wesnousky 2008 database
2010 Christchurch, New Zealand2010 El Mayor
Cucapah, Mexico2009 L’Alquila, Italy
2008
Wenchaun
, China
2006 Machaze, Mozambique2005 Pakistan2004 Parkfield, California
2004 Mid-Niigata, Japan1995 Kobe, Japan1976 Montagua, Guatemala1973 Luhuo, China1931 Funyun, China1905 Bulnay, MongoliaGlenn Biasi University of Nevada Reno14