PREDICTION

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PREDICTION
Paleoseismology Documenting and evaluating past
events. 1.) Usually done with looking at offset
layers in sediments in trenches 2.) Calculate
recurrence interval by using radiometric
dating Carbon14. ND pg. 111 Fig. 4.21/4.22
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PREDICTION
E-W patterns Consider Bay area earth quakes. A
given EQ is usually followed by another in the
near future to the east or west. Fig. 4.27
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PREDICTION
Seismic Gap Areas of fault that seem to be
stuck for periods of time. Recall Elastic
Rebound Theory Consider areas of specific
fault-(Fig. 4.14) Consider general geographic
area-(ND pg. 118/fig. 4.32)
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PREDICTION and WARNING
Some other interesting techniques that we can
use US and JAPAN utilize this technology 1.)
Stainmeters measure the amount of bend in
rocks 2.) Tilt measurements - is the tilt of the
surrounding rock changing? 3.) Radon-crystals
fracture and release radon gas Earth and
Environmental fig. 1.4.2
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PREDICTION and WARNING continued
4.) Groundwater-level and temperature
fluctuations 5.) Electrical conductivity - as
rocks compress they lose resistance
(conductivity increases) 6.) Leveling surveys
and lasers - are different sides of the fault
changing up,down,side to side Earth and
Environmental fig. 1.4.2
While these all provide insight there is NO
OBVIOUS/FORMULAIC pattern to perfect
prediction/warning
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PREDICTION
Intermediate- Long-Term Predictions Can we do
it? Faults can be characterized into 3 main
groups 1.) Quasi-Periodic Major events or
events of certain magnitude happen at nearly
regular intervals 2.) Clustered Movements
movements occur for periods of time (decades)
the quiet for periods of time (centuries) 3.)
Random- Well just that. We got nothin. San
Andreas?
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PREDICTION
BUT!!!!!!! Haicheng China, Winter of
1975 Precursors 1.) land elevation changed
(laser and satellite data collection) 2.) water
level changed unexpectedly (ground and
surface) 3.) minor foreshocks increased in
frequency Action 1.) An evacuation was
ordered 2.) On Feb. 4 a 7.3 hit. 3.) killed
2,041 injured 27,538 4.) potential fatalities
could have been 150,000
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PREDICTION
BUT BUT!!!!! Tangshen China 1.) July 28,
1976 2.) 7.3 EQ 3.) similar tectonic setting NO
precursors recorded 4.) 250,000 people perished.