what are seismographs?
instruments used to detect and record earthquake vibrations
seismographs are instruments used to ____ and _____ earthquake vibrations
what do seismographs detect and record?
The reports you get from a seismograph is called...
Modern seismographs use sensitive _____ and _____
a seismograph measures...
the earth's vibrations in two different directions
How many directions does a seismograph measure the earth's vibrations?
what are the two directions measured by a seismograph?
- the horizontal movement of the Earth - Vertical Earth movement
Energy in earthquakes travels outward as _____
What is the name of the originating point where a tectonic slip occurs?
Earthquake ______ emit outwards from the focus
What are the two broad categories of earthquake waves?
1. 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
P waves can travel through....
solids, liquids, and gases
When P waves are emitted they travel in ______ directions including deep into the Earth
S waves can travel through...
the wave motion of S-waves is...
perpendicular to travel direction
What are s-waves called?
are s-waves faster or slower then p-waves?
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?
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