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Earthquakes and Earth's Interior
Transcript of Earthquakes and Earth's Interior
San Andreas Fault
The most studied system in the world
Has "stick-slip" motion; the fault stores elastic energy for hundreds of years until it ruptures into a great earthquake
Is offset two meters every hundred years and every two-hundred years an earthquake occurs
The study of earthquake waves
Seismologists use seismographs to record and amplify ground motion
The two types of seismic waves are surface waves and body waves
Surface waves move up and down and side-to-side at the same time and are usually the most destructive kind of wave
The greater the interval measured on a seismograph between the first P wave and the first S wave, the greater the distance to the source of the earthquake
Travel-time graphs help to determine the relationship between the actual distance and the interval on the seismogram
To determine the direction to the epicenter (surface above the source), the distance between three different seismic stations and the epicenter are shown as circles and the center of the circles is the epicenter
What is an Earthquake?
Read section 8.1 (p 218-221)
Complete 7 flip-flap foldable for 8.1 vocabulary
Types of Body Waves
Primary waves (P waves) and secondary waves (S waves)
P waves push and pull rock
S waves shake rock up and down
Measuring the Size of Earthquakes
Destruction from Earthquakes
Earthquake damage comes in the form of tsunamis, landslides, fire, and just plain damage from vibrations
Tsunamis result from undersea earthquakes and cause giant waves.
Fires are caused by the severing of gas and electrical lines during the quake
Damage from Vibrations
When soil is saturated with enough water liquefaction occurs. In liquefaction, soil becomes a mobile fluid and can topple buildings.
Soft sediment can amplify seismic waves
Short-range predictions monitor precursors or phenomena that precede earthquakes and must be both accurate and reliable.
Long-range predictions give the probability of an earthquake of a certain magnitude occurring years in the future; they are based on the premise that earthquakes are repetitive.
The three layers of Earth are the crust, the mantle, and the core.
When Earth was formed, iron and nickel melted and sank to form the core and oxygen-rich rock rose to the surface to form the crust.
Oceanic crust is made up of basalt while continental crust is mostly made up of granite.
The mantle is dominantly peridotite and is divided into the lithosphere, asthenosphere, and the lower mantle.
The core is divided into the liquid outer core and the solid inner core.
Detecting Seismic Waves
Earthquakes' seismic waves travel all the way through Earth and can be recorded to give an idea of the different layers of the planet and their temperature and composistion.
The boundary between the crust and mantle otherwise known as the Moho was discovered by Andrija Mohorovicic in 1909.
The Core-Mantle boundary was discovered by Richard Oldham in 1906.
The Inner Core-Outer Core boundary was discovered in 1936 by Inge Lehman
Earthquake size is measured through intensity and magnitude
Intensity is the degree of shaking based on the amount of damage and is measured by the Modified Mercalli Intensity Scale
Magnitude is based on calculations from seismic records that measure the amount of energy released from the source of the earthquake and is rated through the Richter scale
Moment magnitude is another way of measuring earthquakes and is calculated based on how much energy a rock can store
Day 1: What do you Know and Want to know about Earthquakes?
Last 5 minutes: pair share KWL charts and turn in KWL charts.
end of day 1
Exit ticket: fill out KWL chart
END DAY 2