Seismic Waves/Earthquake Notes

Review: Scientists study and record ______data and ______ activity in order to support the theory of plate tectonics. The evidence proves that there is a distinct relationship between seismic activity, volcanic activity, and the lithospheric plate boundaries.

Seismic Data and Plate Tectonics: The interaction along ______boundaries results in an increased frequency (occurrence) of earthquakes at those locations. Additionally, stronger earthquakes are more likely to occur along active plate boundaries. Strong earthquakes are more common at______ and ______plate boundaries. The San Andreas fault in California is an example of an active transform plate boundary.

How are earthquakes measured? Earthquakes are measured using the ______. The strongest earthquake ever measured was a 9.5 on the Richter Scale. This is a measurement of the

amount of energy released from the earthquake. The _Richter Scale expresses or measures the magnitude (energy) of an Earthquake and measures the energy released. The scale goes from 1 to 10 .

Seismic Waves Activity: Illustrate & explain the seismic waves based on the Pop & Lock Activity.

Primary (P) Waves / Secondary (S) Waves / Surface Waves

Seismic Waves (3 types)

______are waves generated by an earthquake that travel through the Earth. These waves can cause the ground to moveforward, backward, up, down, and even to ripple. Seismic Waves are generated at the ______ time but move in different ways, and at different speeds.

There are 3 types of Seismic Waves:

  • ______
  • ______
  • ______

Type of Wave/ Illustration / Position / Movement / Moves through what states of matter
PRIMARY WAVES:
P WAVES
/ The ______seismic wave to move out from the earthquake focus, the point where the energy is released
Travel the ______ of the three waves / ______and______rock creating a back-and-forth motion in the direction the wave is moving…. This known as a (______wave)
A type of seismic wave that compresses and expands the ground / Moves through ______and ______layers of Earth (it also can move in gas)
SECONDARY WAVES:
S WAVES
/ The ______wave to Move out from the earthquake focus
Move ______ than primary waves / Move at ______ to primary waves causing rocks to move up and down and side to side…this is known as a(______wave)
A type of seismic wave that moves the ground up and down or side to side
shear waves - move material perpendicular to wave movement / Can only move through ______ rock
If S-waves can only move through solids, then which EARTH layer can’t it go through?
SURFACE WAVES
/ Form when ______and ______waves reach the ______AND THESE WAVES ARE CONSIDERED THE ______SEISMIC WAVES.
Especially damaging to buildings / Can cause the ground to shake making rock sway from side to side and roll like an ocean wave
Travel just below or along the ground’s surface
Produces motion in the upper crust
Motion can be up and down
Motion can be around
Motion can be back and forth
Mainly moves like P & S waves / Moves through______the states of matter: solid, liquid, and gas

Scientists use the principle that the ______and ______of a seismic wavedepends on the material it travels through. Because of the behavior of these different waves, scientists have indirect evidence for the solid inner core and liquid outer core of Earth; because earthquake waves travel fasterthrough the ______ than through the crust, scientists know that the mantle is denser than the crust.

MEASURING EARTHQUAKES

The energy spreads outward in all directions as vibrations called ______. Seismic waves can be measured and recorded by a ______.

______are instruments or a device that detects and records seismic or earthquake waves. It measures the vertical ground motion and the horizontal ground motions (N-S/E-W). It also traces wave shapes onto paper and translates waves into an electronic signal.

The vibration record, called a ______, looks like jagged lines on paper. Seismograms are traces of amplified, electronically recorded ground motion made by seismographs.

Measuring the time between the arrival of the P and S waves determines the ______between the recording seismograph and the earthquake epicenter.

SEISMOGRAPH / SEISMOGRAM

LOCATING AN EARTHQUAKES EPICENTER

______identifies the epicenter of an earthquake.

The location of an earthquake’s epicenter is found by plotting ______

circles on a map from the records of three seismograph stations and finding the

point where the three circles ______Three seismograph

stations are needed to locate the epicenter of an earthquake. Triangulate means to use three positions to determine an exact location.

How do scientists calculate how far a location is from the epicenter of

an earthquake? CALCULATING THE S-P INTERVAL:

- Scientists calculate the difference between arrival times of the P waves and S waves

- The further away an earthquake is, the greater the time between the arrival of the P waves and the S waves

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