Seismology and Faults Flashcards
what are seismographs?
instruments used to detect and record earthquake vibrations
seismographs are instruments used to ____ and _____ earthquake vibrations
detect, record
what do seismographs detect and record?
earthquake vibrations
The reports you get from a seismograph is called…
a seismogram
Modern seismographs use sensitive _____ and _____
optics, electronics
a seismograph measures…
the earth’s vibrations in two different directions
How many directions does a seismograph measure the earth’s vibrations?
two
what are the two directions measured by a seismograph?
- the horizontal movement of the Earth - Vertical Earth movement
Energy in earthquakes travels outward as _____
waves
What is the name of the originating point where a tectonic slip occurs?
the focus
Earthquake ______ emit outwards from the focus
waves
What are the two broad categories of earthquake waves?
- Surface waves 2. Body waves
Where do surface waves travel?
along the earth’s surface
What are the three characteristics of surface waves?
- travel along earth’s surface - very destructive - are the last to reach the seismograph (slowest)
Where do body waves travel?
Through the Earth’s interior
What are the two types of body waves?
- P waves - S waves
P waves are _______ waves
compressional
P waves can travel through….
solids, liquids, and gases
When P waves are emitted they travel in ______ directions including deep into the Earth
all
S waves can travel through…
any solid
the wave motion of S-waves is…
perpendicular to travel direction
What are s-waves called?
shear waves
are s-waves faster or slower then p-waves?
slower
How is the distance to the epicenter figured out?
- from the seismogram
- by using the arrival times of seismic waves
Which release more energy, earthquakes or volcanoes?
earthquakes
In order for a rock to break it has to have ______ and ______ on it.
stress and strain
What is stress?
the force acting on a surface, per unit area
Stress can be a force that is squezzing, which is called ________ or it can be a force that is pulling a rock apart, which is called _______, or it can be a force that is sliding past a a rock, which is called ______
compression, tension, shear
Compression is a force that is…
squezzing the rock
Tensional force is a force that is…
pulling a rock apart
Shear is a force that is…
sliding past a rock
What is strain?
a rocks response to stress
What are some rock repsones to stress?
it either breaks, squishes, or stretches out, or it changes shape in some other way
As a result of stress and strain, what happens?
rock deformation
What is elastic deformation?
when a rock bends but does not break and once the stress it removed the rock snaps back to its original shape
Which type of deformation do we most commonly see in earthquake situations?
elastic
What is ductile deformation?
when rocks flow or bend but do not break, and do not snap back to their original shapd once the stress is removed
In ductile deformation, does the rock snap back to its original shape?
no
What is brittle deformation?
when rocks crack or break
when rocks crack or break this is called….
brittle deformation
when a rock bends but does not break and once the stress it removed the rock snaps back to its original shape this is called…
elastic deformation
What are the three types of deformation?
elastic, ductile, and brittle
what are the types of stress?
tension, compression, and shear
What are faults?
fractures in the earths crust along which movement is occuring and where we see a lot of stress
What are plate margins?
gigantic faults
why are there faults that occur throughout the earth’s crust?
becuase the earth’s crust is constantly undergoing stress
What are the four types of faults?
- normal
- reverse
- thrust
- transform
A normal fault forms as a result of…
tensional stress
a reverse fault form as a result of, and in response to…
compressional stress
a thrust fault forms in response to…
compressional stress
the angle of a thrust fault is…
closer to horizantal
a transform fault forms in response to…
shear stress
a divergent plate boundary is equivalent to which type of fault?
normal
a convergent plate boundary is equivalent to which type of fault?
reverse/thrust
a transform plate boundary is equivalent to which type of fault?
transform
