EARTHQUAKES cont’d …. September 19 and 20th 8.E.5B.3

FALCON FOCUS THE POINT ON EARTH’S SURFACE WHERE THE GREATEST ENERGY FROM THE EARTHQUAKE IS RELEASED IS ___________. THE EPICENTER THE FOCUS THE ASTHENOSPHERE THE FAULT

ESSENTIAL QUESTION HOW WOULD YOU COMPARE AND CONTRAST THE THREE TYPES OF SEISMIC WAVES?

Performance Indicator 8.E.5B.1 Analyze and interpret data to describe patterns in the location of volcanoes and earthquakes related to tectonic plate boundaries, interactions, and hot spots

Review Scientists study and record seismic data and volcanic 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 plate 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 transform and convergent 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 Richter Scale. 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.

How are Earthquakes Measured? Richter Scale

Focus and Epicenter of Earthquake

SEISMIC WAVES _SEISMIC WAVES___ are waves generated by an earthquake that travel through the Earth. These waves can cause the ground to move forward, backward, up, down, and even to ripple. Seismic Waves are generated at the __SAME___ time but move in different ways, and at different speeds.

Seismic Waves in the Earth http://www.uwgb.edu/dutchs/EarthSC-102VisualsIndex.HTM

3 TYPES OF SEISMIC WAVES PRIMARY (P) WAVES SECONDARY (S) WAVES SURFACE WAVES

Seismic Waves

PRIMARY (P) WAVE Position: The first seismic wave to Move out from the earthquake focus, the point where the energy is released Travel the fastest of the three waves Movement: Push and pull rock creating a back-and-forth motion in the direction the wave is moving… this is known as a (longitudinal wave) A type of seismic wave that compresses and expands the ground

PRIMARY (P) WAVE Moves through what states of matter: Moves through solid and liquid layers of Earth (it also can move in gas)

Primary Waves (P Waves) A type of seismic wave that compresses and expands the ground The first wave to arrive at an earthquake http://daphne.meccahosting.com/~a0000e89/insideearth2.htm

Secondary Waves (S Waves) Position: The 2nd wave to Move out from the earthquake focus Move slower than primary waves Movement: Move at right angles to primary waves causing rocks to move up and down and side to side … this is known as a (transverse wave) A type of seismic wave that moves the ground up and down or side to side

Secondary Waves (S Waves) Moves through what states of matter : Can only move through solid rock Question: If S-waves can only move through solids, then which EARTH layer can’t it go through?

OUTER CORE!!!!

Seismic Waves Paths Through the Earth WHICH WAVES ARE S-WAVES AND WHICH WAVES ARE P-WAVES? HOW DO YOU KNOW? WHERE ARE THE SURFACE WAVES?

Earth’s Interior Showing P and S Wave Paths WHICH EAVES ARE S-WAVES AND WHICH WAVES ARE P-WAVES? HOW DO YOU KNOW? WHERE ARE THE SURFACE WAVES?

Secondary Waves (S Waves) A type of seismic wave that moves the ground up and down or side to side http://daphne.meccahosting.com/~a0000e89/insideearth2.htm

HOW WOULD YOU COMPARE AND CONTRAST PRIMARY & SECONDARY WAVES?

Comparing Seismic Waves

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

ACTIVITY CREATE S, P, AND SURFACE WAVES USING A STRING AND A SLINKY

Primary or “P” Wave Secondary or “S” Wave

SURFACE WAVES POSITION: Form when P and S waves reach the surface AND THESE WAVES ARE CONSIDERED THE MOST DESTRUCTIVE SEISMIC WAVES. Especially damaging to buildings

MOVEMENT: 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 what states of matter Moves through all the states of matter: solid, liquid, and gas

Surface Waves

Scientists use the principle that the speed and direction of a seismic wave depends 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 faster through the mantle than through the crust, scientists know that the mantle is denser than the crust.

Earthquake Waves & Earth’s Interior

Measuring Earthquakes The energy spreads outward in all directions as vibrations called ___Seismic Waves____. Seismic waves can be measured and recorded by a ____seismograph_______. __Seismographs______ 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.

Measuring Earthquakes The vibration record, called a seismogram, 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 distance between the recording seismograph and the earthquake epicenter.

Measuring Earthquakes SEISMOGRAPH SEISMOGRAM

Seismograph

Types of Seismographs

Seismogram Printout

How is an Earthquake’s Epicenter Located? Seismic wave behavior P waves arrive first, then S waves, then L and R Average speeds for all these waves is known After an earthquake, the difference in arrival times at a seismograph station can be used to calculate the distance from the seismograph to the epicenter. How is an Earthquake’s Epicenter Located?

LOCATING AN EARTHQUAKES EPICENTER TRIANGULATION identifies the epicenter of an earthquake. The location of an earthquake’s epicenter is found by plotting 3 circles on a map from the records of three seismograph stations and finding the point where the three circles intersect. Three seismograph stations are needed to locate the epicenter of an earthquake.

Locating an Earthquake EPICENTER

How is an Earthquake’s Epicenter Located? Three seismograph stations are needed to locate the epicenter of an earthquake The intersection of the circles locates the epicenter

Locating an Earthquake Epicenter Triangulate means to use three positions to determine an exact location.

Locating Earthquakes http://www.uwgb.edu/dutchs/EarthSC-102VisualsIndex.HTM

Locating Earthquakes http://www.uwgb.edu/dutchs/EarthSC-102VisualsIndex.HTM

Locating Earthquakes http://www.uwgb.edu/dutchs/EarthSC-102VisualsIndex.HTM

Triangulation of 3 stations to locate earthquake epicenter

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

Earthquake Waves (Review) Primary Wave (P-Wave) First set of waves Move side to side FASTEST wave Secondary Wave (S-Wave) Second set of waves Move up and down Travel slow Surface Wave Move up and down & side to side MOST DANGEROUS SLOWEST Wave

Closure Create a Venn Diagram contrasting and comparing the 2 types of seismic waves.

Homework Study for Quiz Place the following words in your glossary. Primary wave, Secondary wave, Surfaces wave, Longitudinal wave, Transverse wave, Richter Scale, Seismograph, Seismogram, Magnitude, and Intensity.

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