EQ 2: Plate tectonics, Plate boundaries, Faulting

3 types of faults

Normal, reverse (thrust faulting), strike-slip

A fault is what kind of deformation

Brittle fracture

Normal fault info

Extensional or tensional stress

Blocks move away from each other

Hanging wall moves down foot wall

Reverse fault

Compressional stress

Moves towards each other

Hanging wall goes up foot wall

Thrust fault (type of reverse fault)

When the plane is closer to horizontal then vertical compared to other thrust faults

Strike-slip fault

Caused by shear stress

Motion is horizontal

Fault planes close to vertical

No hanging or foot wall

Two types of strike slip faults

Right lateral strike slip

Left lateral strike slip

Divergent plate boundary info

Plates spread across a rift zone

New oceanic lithosphere is created

Rift valley, continued rifting, mature ocean basin with a mid-oceanic ridge

Convergent plate boundary info

If ocean-ocean or ocean continent then subduction zone occurs.

If continent-continent then continent collision.

Where are earthquakes worst?

1) on plate interface

2) in overriding plate

3)within down going subduction plate

Divergent plate boundary EQ depth

Very shallow 10km but mostly 5km and up

Divergent max EQ size

Not very big, max mag 6

Subduction zone depths

3 depths

Plate interface 20-50km

Overriding plate up to 40km deep

Downgoing plate up to 700 km

3 plate boundaries

Convergent, Divergent, Transform

3 types of stresses

Tensional, Compressional Shearing

What are the Plate boundaries, Stress types associated with Normal Faults?

Divergent Boundaries

Tensional Stress

What are the Plate boundaries, Stress types associated with Reverse (and thrust) Faults?

Convergent Boundaries

Compressional stress

What are the Plate boundaries, Stress types associated with Strike slip Faults?

Transform Boundaries

Shear stress

How does compressional stress affect plate?

Plate shortens and thickens, its compressed

How does tensional stress affect plate?

plate extends and thins, its stretched

How does shear stress affect plate?

no extension or shortening