The San Andreas Fault is a continental transform fault that extends roughly 1,200 kilometers through California. It forms the boundary between the Pacific Plate and the North American Plate. The fault results in right-lateral strike-slip motion, with the left side moving northward and the right side moving southward. Major earthquakes are caused by the build up of stress from this motion at various segments of the fault. The fault has had a significant impact throughout California's history, causing damage from earthquakes and other natural disasters.
The San Andreas Fault: A Geological Force Shaping California
1.
2. A Fault is a deep crack in the
earth’s crust, most of them are
found between two tectonic plate
boundaries.
The San Andreas Fault is a
continental transform fault that
extends roughly 1,200 kilometers
(750 mi) through California.
It forms the tectonic boundary
between the Pacific Plate and the
North American Plate, and its
motion is right-lateral strike-slip
San Andreas Fault was named after
San Andreas Lake by geologist A.C.
Lawson in 1895
3. The fault begins in Gulf of
California, and travels
north through Baja, past
the Salton Sea, all the way
up to San Francisco and
exit’s the bay where it
continues to run along the
coast until it ends near
Eureka, California.
The entire San Andreas
fault system is more than
800 miles long and extends
to depths of at least 10
miles within the Earth.
4. Tectonic plates are what make up the earth’s crust where
the oceans and continents rest.
The name of the tectonic plate that sits on the east side of
the San Andreas Fault Line is the North American Plate
and on the west side is the Pacific Plate.
The southwestward motion of the North American Plate
towards the Pacific is creating compressional forces along
the eastern side of the fault. The effect is expressed as the
Coast Ranges.
The northwest movement of the Pacific Plate is also
creating significant compressional forces which are
especially pronounced where the North American Plate has
forced the San Andreas to jog westward.
This has led to the formation of the Transverse Ranges in
Southern California, and to a lesser but still significant
extent,the Santa Cruz Mountains
Age: Neogene-Holocene
5. The San Andreas Fault is
a right lateral strike-slip
fault.
It means that the left side
of the fault is moving
northward towards
Alaska while the right
side is sliding southward
toward Mexico.
6. The fault divides into five segments, each with
different characteristics and a different degree of
earthquake risk.
The most significant being the southern segment,
which passes within about 35 miles (56 km) of Los
Angeles. The slip rate along the fault ranges from 20 to
35 mm (0.79 to 1.38 in)/yr.
Northern Segment
Creeping Segment
Parkfield Segment
Central Segment
Southern Segment
7. The Northern segment of the San Andreas fault
extends from Shelter Cove to south of the San
Francisco Bay area.
8. This portion of the San Andreas fault extends from San
Juan Bautista, near Monterey, to the short Parkfield
segment deep in the Coast Ranges.
It exhibits a phenomenon called aseismic creep, where the
fault slips continuously without causing earthquakes
9. This part of he fault
is at the center of the
San Andreas fault.
Hardly 30 kilometers
long, this segment is
special because it
has its own set of
magnitude-6
earthquakes that
don't involve the
neighboring
segments.
10. This Segment is
defined by the great
rupture of 9 January
1857, a magnitude-8
earthquake that
broke open the
ground for about 350
kilometers from the
hamlet of Cholame
near Parkfield to
Cajon Pass near San
Bernardino.
11. From Cajon Pass, this segment of the San Andreas
fault runs about 300 kilometers to its end on the
shores of the Salton Sea
12. The San Andreas began to form in the mid Cenozoic about 30
Mya. At this time, a spreading center between the Pacific Plate
and the Farallon Plate (which is now mostly subducted, with
remnants including the Juan de Fuca Plate, Rivera Plate, Cocos
Plate, and the Nazca Plate) was beginning to reach the
subduction zone off the western coast of North America.
As the relative motion between the Pacific and North American
Plates was different from the relative motion between the
Farallon and North American Plates, the spreading ridge began
to be "subducted", creating a new relative motion and a new style
of deformation along the plate boundaries.
These geological features are what are chiefly seen along San
Andreas Fault. It also includes a possible driver for the
deformation of the Basin and Range, separation of the Baja
California Peninsula, and rotation of the Transverse Range.
13.
14. Disasters
Earthquakes
Landslide
Flashfloods
Fires
Tsunamis
Result from Disasters
Property Damage
Property Loss
Injury
Death
15. The Great Earthquake
of 1906.
San Francisco
Earthquake of 1989
(also known as the
“World Series”
Earthquake
1994 Northridge Quake
1992Landers
Earthquake