foundation system of burj al arab

Searching Faults: As Earthquake Geologic Evidence (Part-2)

We are discussing about features that should be examined to find out faults in a region or site earthquake geologic evidence. In important and larger project with geotechnical investigation it is also done.

We are now discussing rest features as continuation of previous post as follows:

3. Geomorphic and topographic indicators. Land form is concerned in geomorphic indicator. These indicators include:

a. Offsets in drainage or stream 
Earthquake geologic evidence; offset stream channel by strike slip faulting
b. Change or tilt in elevation of shorelines or terraces

c. Sag ponds which includes water accumulation near faults (strike-slip) in depression
d. Anomalous gradient in streams

e. Topographic scraps
San Andreas Fault: Offset stream as earthquake geologic evidence
f. Triangular corner or ridges


4. Secondary geologic characteristics:

These includes

a. Juxtapositions of hot springs
Earthquake geologic evidence; Juxtapositions of hot springs
b. Changes in chemical composition, alignment and gradient of

–springs

-volcanic vents


5. Features of imagery found from remote sensing device which includes, contrast in

a. vegetation

b. topography

c. tone


6. Geophysical indicators which includes subsurface faulting. The indicators are

a. offsets on earthquake reflection horizons

b. difference in earthquake wave velocity

c. steep magnetic gradient or linear gravity


7. Geodetic indicators which include fault movement appeared as changes in distance or tilting from previous points in geodetic surveys.

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