Download 19FaultingNormal

Faulting landforms from
extension
Normal Faulting
What is a fault?
What is an earthquake?
Online Animations
Earthquake Visualizations
http://serc.carleton.edu/NAGTWorkshops/vis
ualization/collections/earthquakes.html
Fault – rocks snapped
Fault – rocks snapped
Earthquakes occur along
active faults where
energy is stored and
suddenly released when
the stresses along the
fault exceed the frictional
forces resisting motion.
The longer the time
interval (seismic gap)
between seismic events
the greater the
magnitude of the
earthquake.
Earthquakes are the most destructive natural forces on Earth. The Alaskan
earthquake of 1964 was one of the ten most powerful seismic events in the past
century. The image was taken in down town Anchorage.
Structural damage from fire can be greater than that produced from direct groundshaking. The images above are from Kobe, Japan where a 7.0 earthquake struck in
1995. Over $100 billion damage was sustained from structure collapse and fire.
Hanshin Expressway Kobe Japan
Faults and Folds
1. Extension - Normal faulting
2. Compression - Thrust faulting
3. Transform – Strike-slip faulting
4. Folding from Compression
Compression, Tension,
and Shearing Stress
Normal
Folding &
Thrust faulting
Strike-slip
Extension - Normal faulting
Fault Scarp (escarpment)
from single event
El Centro 2010 Earthquake
From Multiple Events
Wasatch Faulting
over Millions of
Years
Over several million years
Sierra Nevada
Normal Fault Scarp Forms
Triangular Facets – produced by
erosion of the fault scarp by
river valleys
Alternating normal faults lead to a characteristic pattern called a
Horst and Graben system. An area under tension will often have
Multiple mountain ranges as a result.
Block Faulting in the
Basin and Range
Why is Basin & Range Extending?
Extension produce deep valleys
filled with gravels (and water)
Extension left blocks high
Sierra Estrella Range
So much extension that the crust
popped back up
Isostacy
demands
that if crust
thins, the root
rises up …
so Camelback
is just a flake
off the bulge
White Tank
Metamorphic
Core
Complex