Tectonic Landforms and Hazards

1. Introduction

2. Folding and faulting

3. Reverse faults

4. Normal faults

5. Transform (strike-slip) faults

6. Tectonic hazards

OROGENIES and OROGENESIS

Examples (Christopherson, 2012, p. 343-345):

1. Laramide orogeny (Rockies), 40-80 my BP

2. Nevadan orogeny, 29-35 my BP

3. Allegheny orogeny (Appalachians), 250-300

my BP

4. Alpine orogeny (European Alps), 2-66 my BP

5. Himalayan orogeny, 45-54 my BP

Continental shields. Source: Christopherson, 2012, p. 336.

Continental shields and exotic terranes.

Source: Christopherson, 2012, p. 338.

Folds and faults. Source: Christopherson, 2012, p. 340.

Compressional force

Development of folds due to compression.

Compressional force

Anticline

Syncline

Asymmetric/recumbent folds

(overturned anticline)

Development of folds due to compression.

Malan’s Peak (anticline), Ogden, UT.

Compressional force Fault plane

Development of a fault from folding: a reverse

(thrust) fault, the result of compression.

Fault plane

Reverse (thrust) fault: result

of compressional stress. Source: Christopherson, 2012, p.342.

Normal fault: result of tensional stress. Source: Christopherson, 2012, p.342.

Transform (strike-slip) fault: result of lateral

(shearing) stress. Source: Christopherson, 2012, p.342.

Fault plane

Reverse (thrust) fault: result

of compressional stress. Source: Christopherson, 2012, p.342.

Fault scarp

produced by a

reverse (thrust)

fault in Algeria,

following

magnitude 7.3

earthquake, 1980. Source: Bloom, 1998; photo by M.

Meghraoui.

Normal fault: result of tensional stress. Source: Christopherson, 2012, p.342.

Triangular facets

indicating normal fault scarps

Normal faults along the Wasatch Front.

Triangular facets near Mapleton, UT.

Source: Utah Geological Survey, 1996.

Triangular facets near Ogden, UT, viewed from Highway 89.

Triangular facets near Ogden, UT, viewed from Highway 89.

Source: David Schultz, Pictures from 2002 Winter Olympic Weather Forecaster Training

http://www.cimms.ou.edu/~schultz/olympics/images/img20.gif

Aerial photo of Weber Canyon and the Wasatch Front.

Diagram of the

Wasatch Fault:

a NORMAL fault.

Source: UGS, 1996.

Graben (down-faulted block)

Horst (up-faulted block)

Horst and graben: features of extensional stress. Source: Christopherson, 2012, p.345.

The Basin and

Range province

of the western U.S. Source: NASA Goddard Space Flight Center.

Transform (strike-slip) fault: result of lateral

(shearing) stress. Source: Christopherson, 2012, p.342.

The San Andreas Fault- An Example of a

Transform Fault. Source: Christopherson, 2012, p. 344.

Effects of a transform fault, southern California.

Source: Cornell University Geology Department, Geo 101 image gallery.

Effects of the San Andreas fault.

Source: University of Washington Department of Geophysics, magnetotellurics research.

Utah earthquakes,

1977-1996. Source: USGS National Earthquake

Information Center.

Map showing general

location of the Wasatch

Fault in Utah. Source: USGS.

Focus

Epicentre

Focus and epicentre at the Loma Prieta

earthquake, CA, 1989. Source: Christopherson, 2012, p. 350.

Diagram of the

Wasatch Fault:

a NORMAL fault.

Source: UGS, 1996.

Ground shaking

response to a M7.0

earthquake on the

Wasatch Fault. Source:

Utah Geological Survey.

Liquefaction

potential map for

Salt Lake County.

Source: Utah Geological Survey.

High: 50% in 100 years

Moderate: 10-50%

Low: 5-10%

Very low: less than 5%

Liquefaction potential:

Weber

County.Source: Utah

Geological

Survey.

High

Moderate

Low