Geology 1001.4
    Dr. Dutrow
EARTHQUAKES

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Violent oscillatory motion of the ground

 

 

Elastic rebound theory - faults remain locked while strain energy accumulates

 

 

Focus -

 

 

Epicenter -

 

 

Seismic waves - elastic energy

 

 

Damage - generally the greatest damage

 

 

 
MEASURING EARTHQUAKES

 

Seismographs - measures

 

 

Seismic waves - three types

 

P-waves (primary) -

 

 

S-waves (secondary) -

 

 

 

Surfaces waves -

 

 

 

 Locating earthquake epicenters (how to do it)

 

(1) time

 

 

 

(2) multiple seismographs

 

 

 Size of the earthquake (1) maximum

 

 

(2) developed

 

 

(3) actual effects

 

 

 

 

STRESS PATTERNS OF FAULTS

 

Earthquakes develop

 

- the direction of the slip

 

- can establish direction of slip

 

 

normal faulting -

 

 

reverse or thrust fault -

 

 

 

strike-slip faulting -

 

 

 
 
DESTRUCTIVENESS OF EARTHQUAKES

 

(1) Ground vibrations - shake

 

 

 

(2) Liquefaction - soils and sediments

 

 

 

(3) Tsunamis - waves

 

 

 

(4) Fire -

 

 

 

To reduce some hazards

 

 

 

 

Prediction of earthquakes?

 

Still difficult

 

 
 
 
HOW BIG, HOW MANY EARTHQUAKES?

 

 Typically the interval between the largest quakes

 

 

 

 

WHERE DO THEY OCCUR?

 

Most commonly occur at plate boundaries

 

(1) shallow quakes

 

 

(2) shallow quakes

 

 

(3) shallow and deep earthquakes

 

 

 

Other places

 

- quakes associated with

 

 

 

- within plate stress

 

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