EARTHQUAKES- Chapt.19 Flashcards
Three types of stress and strains.
Compression, Tension, Shear
It is caused by horizontal shear.
Strike-slip Faults
Forms as a result of horizontal and vertical compression that squeezes rock and creates a shortening of the crust.
Reverse and Normal Faults
Types of Seismic Waves:
-Primary Waves (P-waves): Squeeze and push rocks in the direction along which the waves are traveling.
-Secondary Waves (S-waves): Have a motion that causes rocks to move at right angles in relation to the direction of the waves.
-Surface Waves: Third and slowest type of waves/ Can cause the ground to move sideways and up and down like ocean waves.
TWO Generations of Seismic Waves
Focus- The place inside Earth’s crust where an earthquake originates.
Epicenter- The point on the Earth’s surface directly above the focus.
The internal part of the seismograph, which may be a pendulum or a mass mounted on a spring. Is the measuring instrument that creates the seismogram.
Seismometer
The recording of the ground shaking at the specific location of the instrument.
Seismogram
Clues to Earth’s Interior:
Earth’s Composition: Shows that seismic waves change their speed and paths as they encounter boundaries between zones of different materials.
Imaging Earth’s Interior: Seismic wave speed and Earth’s density vary with factors other than depth.
The energy of seismic waves produced during during an earthquake.
Magnitude
The height of seismic waves produced during during an earthquake.
Amplitude
The amount of damage caused by earthquakes.
Intensity
Methods for Describing the Size of an Earthquake:
-Richter scale
-Moment magnitude scale
-Modified Mercalli scale
Factors that determine intensity:
-Amplitude of surface waves generated.
-Surface Waves
-Depth of Focus
-Shallow-focus Earthquake (Most damaging)
-Intermediate-focus Earthquake
-Deep-focus Earthquake (Least damaging)
