SEISMOTECTONICS OF STRIKE-SLIP PLATE BOUNDARIES Non …thorne/EART118/Lecture_PDF/lecture19.pdf ·...
Transcript of SEISMOTECTONICS OF STRIKE-SLIP PLATE BOUNDARIES Non …thorne/EART118/Lecture_PDF/lecture19.pdf ·...
![Page 1: SEISMOTECTONICS OF STRIKE-SLIP PLATE BOUNDARIES Non …thorne/EART118/Lecture_PDF/lecture19.pdf · SEISMOTECTONICS OF STRIKE-SLIP PLATE BOUNDARIES Non-Ridge Transform/Transcurrent](https://reader034.fdocuments.net/reader034/viewer/2022050717/5e14edebb4c16d13ab5538a4/html5/thumbnails/1.jpg)
SEISMOTECTONICS OF STRIKE-SLIP PLATE BOUNDARIESNon-Ridge Transform/Transcurrent Faults
![Page 2: SEISMOTECTONICS OF STRIKE-SLIP PLATE BOUNDARIES Non …thorne/EART118/Lecture_PDF/lecture19.pdf · SEISMOTECTONICS OF STRIKE-SLIP PLATE BOUNDARIES Non-Ridge Transform/Transcurrent](https://reader034.fdocuments.net/reader034/viewer/2022050717/5e14edebb4c16d13ab5538a4/html5/thumbnails/2.jpg)
San Andreas strike-slip boundary betweenPacific and North American plates.
Right-lateral strike-slipfault. Formally a transform fault connecting spreadingridge in Gulf ofCalifornia to ridgetransform fault ofMendocino fault.
![Page 3: SEISMOTECTONICS OF STRIKE-SLIP PLATE BOUNDARIES Non …thorne/EART118/Lecture_PDF/lecture19.pdf · SEISMOTECTONICS OF STRIKE-SLIP PLATE BOUNDARIES Non-Ridge Transform/Transcurrent](https://reader034.fdocuments.net/reader034/viewer/2022050717/5e14edebb4c16d13ab5538a4/html5/thumbnails/3.jpg)
The San Andreasdoes not have uniform frictionalsliding properties.Stick-slip in northand south, but stablesliding (creeping)in the middle.
The creeping sectionhas many smallevents, but no recordof large events.
Last large event innorth was 1906,in south was 1857.
![Page 4: SEISMOTECTONICS OF STRIKE-SLIP PLATE BOUNDARIES Non …thorne/EART118/Lecture_PDF/lecture19.pdf · SEISMOTECTONICS OF STRIKE-SLIP PLATE BOUNDARIES Non-Ridge Transform/Transcurrent](https://reader034.fdocuments.net/reader034/viewer/2022050717/5e14edebb4c16d13ab5538a4/html5/thumbnails/4.jpg)
Strike-slip faults tend to have irregularitiesthat produce steps, jogs, and associatedalong-strike features.
![Page 5: SEISMOTECTONICS OF STRIKE-SLIP PLATE BOUNDARIES Non …thorne/EART118/Lecture_PDF/lecture19.pdf · SEISMOTECTONICS OF STRIKE-SLIP PLATE BOUNDARIES Non-Ridge Transform/Transcurrent](https://reader034.fdocuments.net/reader034/viewer/2022050717/5e14edebb4c16d13ab5538a4/html5/thumbnails/5.jpg)
![Page 6: SEISMOTECTONICS OF STRIKE-SLIP PLATE BOUNDARIES Non …thorne/EART118/Lecture_PDF/lecture19.pdf · SEISMOTECTONICS OF STRIKE-SLIP PLATE BOUNDARIES Non-Ridge Transform/Transcurrent](https://reader034.fdocuments.net/reader034/viewer/2022050717/5e14edebb4c16d13ab5538a4/html5/thumbnails/6.jpg)
![Page 7: SEISMOTECTONICS OF STRIKE-SLIP PLATE BOUNDARIES Non …thorne/EART118/Lecture_PDF/lecture19.pdf · SEISMOTECTONICS OF STRIKE-SLIP PLATE BOUNDARIES Non-Ridge Transform/Transcurrent](https://reader034.fdocuments.net/reader034/viewer/2022050717/5e14edebb4c16d13ab5538a4/html5/thumbnails/7.jpg)
Salton Sea is depressionin a right-stepping jumpin the fault between theImperial fault and SanAndreas. This is likelyhard for earthquake torupture through, so issouthern limit of bigruptures on San Andreas.
![Page 8: SEISMOTECTONICS OF STRIKE-SLIP PLATE BOUNDARIES Non …thorne/EART118/Lecture_PDF/lecture19.pdf · SEISMOTECTONICS OF STRIKE-SLIP PLATE BOUNDARIES Non-Ridge Transform/Transcurrent](https://reader034.fdocuments.net/reader034/viewer/2022050717/5e14edebb4c16d13ab5538a4/html5/thumbnails/8.jpg)
Transpression inthe big bendleads to slippartitioning withthrust on shallowdipping faults onsouthern side ofthe San GabrielMountains andvertical strike-slipon the San Andreas.
![Page 9: SEISMOTECTONICS OF STRIKE-SLIP PLATE BOUNDARIES Non …thorne/EART118/Lecture_PDF/lecture19.pdf · SEISMOTECTONICS OF STRIKE-SLIP PLATE BOUNDARIES Non-Ridge Transform/Transcurrent](https://reader034.fdocuments.net/reader034/viewer/2022050717/5e14edebb4c16d13ab5538a4/html5/thumbnails/9.jpg)
TRIPLE JUNCTIONS EVOLVE & MIGRATE WITH TIME:Pacific-North America - Farallon (Juan de Fuca) evolution caused
formation of San Andreas and opening of Gulf of California
USGS
![Page 10: SEISMOTECTONICS OF STRIKE-SLIP PLATE BOUNDARIES Non …thorne/EART118/Lecture_PDF/lecture19.pdf · SEISMOTECTONICS OF STRIKE-SLIP PLATE BOUNDARIES Non-Ridge Transform/Transcurrent](https://reader034.fdocuments.net/reader034/viewer/2022050717/5e14edebb4c16d13ab5538a4/html5/thumbnails/10.jpg)
TRIPLEJUNCTIONSEVOLVE &
MIGRATE WITHTIME
Kula-Farallon-Pacific TJmigrates
Kula platevanishes
Farallon breaksup into Juan de
Fuca, Rivera, andCocos
Cocos-Nazcaspreading center
forms
Atwater website
![Page 11: SEISMOTECTONICS OF STRIKE-SLIP PLATE BOUNDARIES Non …thorne/EART118/Lecture_PDF/lecture19.pdf · SEISMOTECTONICS OF STRIKE-SLIP PLATE BOUNDARIES Non-Ridge Transform/Transcurrent](https://reader034.fdocuments.net/reader034/viewer/2022050717/5e14edebb4c16d13ab5538a4/html5/thumbnails/11.jpg)
Atwaterwebsite
![Page 12: SEISMOTECTONICS OF STRIKE-SLIP PLATE BOUNDARIES Non …thorne/EART118/Lecture_PDF/lecture19.pdf · SEISMOTECTONICS OF STRIKE-SLIP PLATE BOUNDARIES Non-Ridge Transform/Transcurrent](https://reader034.fdocuments.net/reader034/viewer/2022050717/5e14edebb4c16d13ab5538a4/html5/thumbnails/12.jpg)
![Page 13: SEISMOTECTONICS OF STRIKE-SLIP PLATE BOUNDARIES Non …thorne/EART118/Lecture_PDF/lecture19.pdf · SEISMOTECTONICS OF STRIKE-SLIP PLATE BOUNDARIES Non-Ridge Transform/Transcurrent](https://reader034.fdocuments.net/reader034/viewer/2022050717/5e14edebb4c16d13ab5538a4/html5/thumbnails/13.jpg)
![Page 14: SEISMOTECTONICS OF STRIKE-SLIP PLATE BOUNDARIES Non …thorne/EART118/Lecture_PDF/lecture19.pdf · SEISMOTECTONICS OF STRIKE-SLIP PLATE BOUNDARIES Non-Ridge Transform/Transcurrent](https://reader034.fdocuments.net/reader034/viewer/2022050717/5e14edebb4c16d13ab5538a4/html5/thumbnails/14.jpg)
![Page 15: SEISMOTECTONICS OF STRIKE-SLIP PLATE BOUNDARIES Non …thorne/EART118/Lecture_PDF/lecture19.pdf · SEISMOTECTONICS OF STRIKE-SLIP PLATE BOUNDARIES Non-Ridge Transform/Transcurrent](https://reader034.fdocuments.net/reader034/viewer/2022050717/5e14edebb4c16d13ab5538a4/html5/thumbnails/15.jpg)
Atwaterwebsite
FORMATION OFTRANSVERSERANGES
LA
SAF
![Page 16: SEISMOTECTONICS OF STRIKE-SLIP PLATE BOUNDARIES Non …thorne/EART118/Lecture_PDF/lecture19.pdf · SEISMOTECTONICS OF STRIKE-SLIP PLATE BOUNDARIES Non-Ridge Transform/Transcurrent](https://reader034.fdocuments.net/reader034/viewer/2022050717/5e14edebb4c16d13ab5538a4/html5/thumbnails/16.jpg)
There are a lot of seismic stations operatingin California, most areoperated by the USGS,Caltech, Berkeley andCDMG.
With so many stations, wehave extensive catalogsof small earthquakes.
![Page 17: SEISMOTECTONICS OF STRIKE-SLIP PLATE BOUNDARIES Non …thorne/EART118/Lecture_PDF/lecture19.pdf · SEISMOTECTONICS OF STRIKE-SLIP PLATE BOUNDARIES Non-Ridge Transform/Transcurrent](https://reader034.fdocuments.net/reader034/viewer/2022050717/5e14edebb4c16d13ab5538a4/html5/thumbnails/17.jpg)
![Page 18: SEISMOTECTONICS OF STRIKE-SLIP PLATE BOUNDARIES Non …thorne/EART118/Lecture_PDF/lecture19.pdf · SEISMOTECTONICS OF STRIKE-SLIP PLATE BOUNDARIES Non-Ridge Transform/Transcurrent](https://reader034.fdocuments.net/reader034/viewer/2022050717/5e14edebb4c16d13ab5538a4/html5/thumbnails/18.jpg)
![Page 19: SEISMOTECTONICS OF STRIKE-SLIP PLATE BOUNDARIES Non …thorne/EART118/Lecture_PDF/lecture19.pdf · SEISMOTECTONICS OF STRIKE-SLIP PLATE BOUNDARIES Non-Ridge Transform/Transcurrent](https://reader034.fdocuments.net/reader034/viewer/2022050717/5e14edebb4c16d13ab5538a4/html5/thumbnails/19.jpg)
Events prior to 1906lack seismic recordings,but are well documentedfrom shaking reportsand surface offsets.
1872 is Owen’s valleyNormal faulting.
1952 is Kern CountyEarthquake on GarlockFault
1868 is on Hayward fault
1872
1857
18681906
1838
1812
1952
1992
![Page 20: SEISMOTECTONICS OF STRIKE-SLIP PLATE BOUNDARIES Non …thorne/EART118/Lecture_PDF/lecture19.pdf · SEISMOTECTONICS OF STRIKE-SLIP PLATE BOUNDARIES Non-Ridge Transform/Transcurrent](https://reader034.fdocuments.net/reader034/viewer/2022050717/5e14edebb4c16d13ab5538a4/html5/thumbnails/20.jpg)
Seismicity near the San Andreas fault is shallow, almost all events are at depthsless than 15 km.
![Page 21: SEISMOTECTONICS OF STRIKE-SLIP PLATE BOUNDARIES Non …thorne/EART118/Lecture_PDF/lecture19.pdf · SEISMOTECTONICS OF STRIKE-SLIP PLATE BOUNDARIES Non-Ridge Transform/Transcurrent](https://reader034.fdocuments.net/reader034/viewer/2022050717/5e14edebb4c16d13ab5538a4/html5/thumbnails/21.jpg)
The northern end ofthe San Andreas isthe Cape Mendocinotriple junction withMendocino transformfault, Gorda plate subduction zone, andSan Andreas Fault.
The seismicity is lowon the SAF. High inlandin the crust above theslabless window.
![Page 22: SEISMOTECTONICS OF STRIKE-SLIP PLATE BOUNDARIES Non …thorne/EART118/Lecture_PDF/lecture19.pdf · SEISMOTECTONICS OF STRIKE-SLIP PLATE BOUNDARIES Non-Ridge Transform/Transcurrent](https://reader034.fdocuments.net/reader034/viewer/2022050717/5e14edebb4c16d13ab5538a4/html5/thumbnails/22.jpg)
The Bay Area is distinctivein splaying of the San Andreas into the Calaverasand Hayward faults andthe northward extension alongthe Rodgers Creek Fault.
![Page 23: SEISMOTECTONICS OF STRIKE-SLIP PLATE BOUNDARIES Non …thorne/EART118/Lecture_PDF/lecture19.pdf · SEISMOTECTONICS OF STRIKE-SLIP PLATE BOUNDARIES Non-Ridge Transform/Transcurrent](https://reader034.fdocuments.net/reader034/viewer/2022050717/5e14edebb4c16d13ab5538a4/html5/thumbnails/23.jpg)
The creeping sectionhas lots of small eventsand ends just northof Parkfield, which hashad repeated magnitude6.0 size events. 6 since1857. The SAF is veryquiet to the south, alongthe rupture zone of the1857 event.
![Page 24: SEISMOTECTONICS OF STRIKE-SLIP PLATE BOUNDARIES Non …thorne/EART118/Lecture_PDF/lecture19.pdf · SEISMOTECTONICS OF STRIKE-SLIP PLATE BOUNDARIES Non-Ridge Transform/Transcurrent](https://reader034.fdocuments.net/reader034/viewer/2022050717/5e14edebb4c16d13ab5538a4/html5/thumbnails/24.jpg)
![Page 25: SEISMOTECTONICS OF STRIKE-SLIP PLATE BOUNDARIES Non …thorne/EART118/Lecture_PDF/lecture19.pdf · SEISMOTECTONICS OF STRIKE-SLIP PLATE BOUNDARIES Non-Ridge Transform/Transcurrent](https://reader034.fdocuments.net/reader034/viewer/2022050717/5e14edebb4c16d13ab5538a4/html5/thumbnails/25.jpg)
![Page 26: SEISMOTECTONICS OF STRIKE-SLIP PLATE BOUNDARIES Non …thorne/EART118/Lecture_PDF/lecture19.pdf · SEISMOTECTONICS OF STRIKE-SLIP PLATE BOUNDARIES Non-Ridge Transform/Transcurrent](https://reader034.fdocuments.net/reader034/viewer/2022050717/5e14edebb4c16d13ab5538a4/html5/thumbnails/26.jpg)
![Page 27: SEISMOTECTONICS OF STRIKE-SLIP PLATE BOUNDARIES Non …thorne/EART118/Lecture_PDF/lecture19.pdf · SEISMOTECTONICS OF STRIKE-SLIP PLATE BOUNDARIES Non-Ridge Transform/Transcurrent](https://reader034.fdocuments.net/reader034/viewer/2022050717/5e14edebb4c16d13ab5538a4/html5/thumbnails/27.jpg)
With extensive seismic stations, can determine focal mechanisms for all eventsdown to very small magnitude of ~2.0.
![Page 28: SEISMOTECTONICS OF STRIKE-SLIP PLATE BOUNDARIES Non …thorne/EART118/Lecture_PDF/lecture19.pdf · SEISMOTECTONICS OF STRIKE-SLIP PLATE BOUNDARIES Non-Ridge Transform/Transcurrent](https://reader034.fdocuments.net/reader034/viewer/2022050717/5e14edebb4c16d13ab5538a4/html5/thumbnails/28.jpg)
![Page 29: SEISMOTECTONICS OF STRIKE-SLIP PLATE BOUNDARIES Non …thorne/EART118/Lecture_PDF/lecture19.pdf · SEISMOTECTONICS OF STRIKE-SLIP PLATE BOUNDARIES Non-Ridge Transform/Transcurrent](https://reader034.fdocuments.net/reader034/viewer/2022050717/5e14edebb4c16d13ab5538a4/html5/thumbnails/29.jpg)
![Page 30: SEISMOTECTONICS OF STRIKE-SLIP PLATE BOUNDARIES Non …thorne/EART118/Lecture_PDF/lecture19.pdf · SEISMOTECTONICS OF STRIKE-SLIP PLATE BOUNDARIES Non-Ridge Transform/Transcurrent](https://reader034.fdocuments.net/reader034/viewer/2022050717/5e14edebb4c16d13ab5538a4/html5/thumbnails/30.jpg)
![Page 31: SEISMOTECTONICS OF STRIKE-SLIP PLATE BOUNDARIES Non …thorne/EART118/Lecture_PDF/lecture19.pdf · SEISMOTECTONICS OF STRIKE-SLIP PLATE BOUNDARIES Non-Ridge Transform/Transcurrent](https://reader034.fdocuments.net/reader034/viewer/2022050717/5e14edebb4c16d13ab5538a4/html5/thumbnails/31.jpg)
![Page 32: SEISMOTECTONICS OF STRIKE-SLIP PLATE BOUNDARIES Non …thorne/EART118/Lecture_PDF/lecture19.pdf · SEISMOTECTONICS OF STRIKE-SLIP PLATE BOUNDARIES Non-Ridge Transform/Transcurrent](https://reader034.fdocuments.net/reader034/viewer/2022050717/5e14edebb4c16d13ab5538a4/html5/thumbnails/32.jpg)
![Page 33: SEISMOTECTONICS OF STRIKE-SLIP PLATE BOUNDARIES Non …thorne/EART118/Lecture_PDF/lecture19.pdf · SEISMOTECTONICS OF STRIKE-SLIP PLATE BOUNDARIES Non-Ridge Transform/Transcurrent](https://reader034.fdocuments.net/reader034/viewer/2022050717/5e14edebb4c16d13ab5538a4/html5/thumbnails/33.jpg)
![Page 34: SEISMOTECTONICS OF STRIKE-SLIP PLATE BOUNDARIES Non …thorne/EART118/Lecture_PDF/lecture19.pdf · SEISMOTECTONICS OF STRIKE-SLIP PLATE BOUNDARIES Non-Ridge Transform/Transcurrent](https://reader034.fdocuments.net/reader034/viewer/2022050717/5e14edebb4c16d13ab5538a4/html5/thumbnails/34.jpg)
![Page 35: SEISMOTECTONICS OF STRIKE-SLIP PLATE BOUNDARIES Non …thorne/EART118/Lecture_PDF/lecture19.pdf · SEISMOTECTONICS OF STRIKE-SLIP PLATE BOUNDARIES Non-Ridge Transform/Transcurrent](https://reader034.fdocuments.net/reader034/viewer/2022050717/5e14edebb4c16d13ab5538a4/html5/thumbnails/35.jpg)