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

PREDICTION

E-W patterns: Consider Bay area earth quakes.

*A given EQ is usually followed by another inthe near future to the east or west.

Fig. 4.27

PREDICTION

Seismic Gap: Areas of fault that seem tobe 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)

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

While these all provide insight

there is NO OBVIOUS/FORMULAIC pattern to

perfect prediction/warning

4.) Groundwater-level and temperature fluctuations

5.) Electrical conductivity - as rocks compress they loseresistance (conductivity increases)

6.) Leveling surveys and lasers - are different sides of thefault changing up,down,side to side

Earth and Environmental fig. 1.4.2

PREDICTION and WARNING continued

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 periodsof time (decades) the quiet for periods of time (centuries)

3.) Random- Well just that. We got nothin’. San Andreas?

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 ordered2.) On Feb. 4 a 7.3 hit.3.) killed 2,041 injured 27,5384.) potential fatalities could have been 150,000

PREDICTION

BUT BUT!!!!!

Tangshen China1.) July 28, 19762.) 7.3 EQ3.) similar tectonic setting NO precursors recorded4.) 250,000 people perished.