Faults
My Blogs (olelog) are mainly based on my daily
reading of earth science news.
Here on whatonearth.olehnielsen.dk I try to weave
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Faults |
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My Blogs (olelog) are mainly based on my daily
reading of earth science news.
Here on whatonearth.olehnielsen.dk I try to weave
some of the pieces together to a greater whole with added background info.
|
||
Dip-slip faults are inclined fractures where the blocks have mostly shifted vertically.
If the rock mass above an inclined fault moves down, the fault is termed normal.
The fault
plane is the planar (flat) surface along which there is slip during an earthquake.
Reverse
FaultIf the rock mass above an inclined fault moves down, the fault is termed reverse.
Thrust FaultA thrust fault is a reverse fault with a dip of 45° or less.
The ramp is where the fault cuts across the bedding.
A thrust-fault flat is a bedding-parallel slip surface along which lateral displacement takes place.
The
rock mass displaced over a thrust fault is a hanging-wall block.
The rock below a thrust fault is a footwall block.
Strike Slip Faults
En echelon
patterns. Faults of like sense in a strike-slip fault zone and oriented
in en echelon patterns. For structures to be "en echelon" they
must be parallel to one another and they must be arranged along a common line
of bearing.
A transform fault is where plates slide past each other. Most transform faults are found on the ocean floor. They commonly offset the active spreading ridges, producing zig-zag plate margins. They are generally defined by shallow earthquakes. A few occur on land, for example the San Andreas fault in California.
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