Figure 12.3 Elastic deformation, rupture, and
elastic rebound
When rocks return to their original shape after being strained what is it called?
The rocks then have three possible responses to increasing stress:
elastic deformation
, plastic deformation, or fracturing. Elastic deformation occurs when the rock returns to its original shape when the stress is removed.
What is true of reflection versus refraction?
Reflection involves a change in direction of waves when they bounce off a barrier
. Refraction of waves involves a change in the direction of waves as they pass from one medium to another. Refraction, or the bending of the path of the waves, is accompanied by a change in speed and wavelength of the waves.
What happens when the rocks are strained past a certain point?
When the accumulated strain is great enough to overcome the strength of the rocks, the result is a sudden break, or a springing back to the original shape as much as possible,
a jolt which is felt on the surface as an earthquake
.
What happens to the rocks when the built up strain on the rocks is released?
Earthquakes
& Earth’s Interior. Earthquakes occur when energy stored in elastically strained rocks is suddenly released. This release of energy causes intense ground shaking in the area near the source of the earthquake and sends waves of elastic energy, called seismic waves, throughout the Earth.
What are the 3 fault types?
There are three main types of fault which can cause earthquakes:
normal, reverse (thrust) and strike-slip
. Figure 1 shows the types of faults that can cause earthquakes.
What is it called when rocks breaks or snap due to stress?
In response to stress, rocks will undergo some form of bending or breaking, or both. The bending or breaking of rock is called
deformation or strain
. … If a rock bends and stays bent after stress is released, it is said to undergo plastic behavior. A combination of elastic and brittle behavior causes earthquakes.
Why does refraction occur?
When the light rays are on the boundary of two media (let’s say water and air) there
is not only a change in the speed of light but also in the change in the wavelength
. This results in the change in the direction of light. This change in speed and wavelength of light causes refraction of light.
What is difference between reflection refraction and diffraction?
Reflection occurs when light bounces off a surface. Refraction is the
bending of
light when it travels from one media to another. Diffraction is the spreading of light when it passes through a narrow opening or around an object.
What is difference between reflection and diffraction?
Reflection of light occurs when light rays strike a surface and
bounce
back or reflect off it. … Diffraction is when light waves bend around obstacles placed in their path and bend into the shadow region.
What is tensional stress?
Tensional stress is
the stress that tends to pull something apart
. It is the stress component perpendicular to a given surface, such as a fault plane, that results from forces applied perpendicular to the surface or from remote forces transmitted through the surrounding rock.
How do rock handle stress?
Rock can respond to stress in three ways:
it can deform elastically, it can deform plastically
, and it can break or fracture. Elastic strain is reversible; if the stress is removed, the rock will return to its original shape just like a rubber band that is stretched and released.
What factors control the response of rocks to stress?
A rock’s response to stress depends on
the rock type, the surrounding temperature
, and pressure conditions the rock is under, the length of time the rock is under stress, and the type of stress.
How many earthquakes a year are actually strong enough to damage property?
An estimated 500,000 detectable earthquakes occur in the world each year. About
100,000
of those can be felt and 100 of them cause damage.
What is the measure of how much damage an earthquake causes the surface?
Intensity
is a measure of the shaking and damage caused by the earthquake; this value changes from location to location.
What force causes folding?
(a) Fig. 10.6a:
Compressive forces
generate folding and faulting as a consequence of shortening. Compressive forces are common along convergent plate boundaries resulting in mountain ranges.
