Lecture topic 6: Tectonic landforms and hazards

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.
Development of folds due to compression.
Compressional force
Development of folds due to compression.
Compressional force
Anticline
Syncline
Asymmetric/recumbent folds
(overturned anticline)
Malan’s Peak (anticline), Ogden, UT.
Development of a fault from folding: a reverse
(thrust) fault, the result of compression.
Compressional force
Fault plane
Reverse (thrust) fault: result
of compressional stress.
Source: Christopherson, 2012, p.342.
Fault plane
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.
Reverse (thrust) fault: result
of compressional stress.
Source: Christopherson, 2012, p.342.
Fault plane
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.
Normal faults along the Wasatch Front.
Triangular facets
indicating normal fault scarps
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.
Aerial photo of Weber Canyon and the Wasatch Front.
Source: David Schultz, Pictures from 2002 Winter Olympic Weather Forecaster Training
http://www.cimms.ou.edu/~schultz/olympics/images/img20.gif
Diagram of the
Wasatch Fault:
a NORMAL fault.
Source: UGS, 1996.
Horst and graben: features of extensional stress.
Source: Christopherson, 2012, p.345.
Horst (up-faulted block)
Graben (down-faulted block)
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 and epicentre at the Loma Prieta
earthquake, CA, 1989. Source: Christopherson, 2012, p. 350.
Epicentre
Focus
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.
Low
Source: Utah
Geological
Survey.
High
Moderate

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